2002-02-22 20:48:55 +08:00
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2002-11-11 03:48:41 +08:00
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Otvety na chasto zadavaemye voprosy po PostgreSQL
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2002-04-12 17:17:10 +08:00
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2003-06-03 00:39:06 +08:00
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Data poslednego obnovleniya: Ponedel'nik 22 Aprelya 14:02:41 EDT 2003
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Anglijskij variant soprovozhdaet: Bryus Mom'yan (Bruce Momjian)
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2002-04-12 17:17:10 +08:00
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(pgman@candle.pha.pa.us)
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2002-11-11 03:48:41 +08:00
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Perevel na russkij: Viktor Vislobokov (victor_v@permonline.ru)
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Samuyu svezhuyu anglijskuyu versiyu dokumenta mozhno najti na
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2003-03-07 13:46:51 +08:00
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http://www.PostgreSQL.org/docs/faqs/FAQ.html.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Otvety na voprosy specifichnye dlya konkretnyh platform mozhno najti
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2003-03-07 13:46:51 +08:00
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na http://www.PostgreSQL.org/docs/index.html.
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2002-04-12 17:17:10 +08:00
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_________________________________________________________________
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2002-11-11 03:48:41 +08:00
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Obschie voprosy
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.1) CHto takoe PostgreSQL? Kak proiznositsya `eto nazvanie?
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1.2) Kakovy avtorskie prava na PostgreSQL?
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1.3) Na kakih Unix platformah rabotaet PostgreSQL?
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1.4) Suschestvuyut li versii portirovannye ne na Unix sistemy?
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1.5) Gde mozhno vzyat' PostgreSQL?
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1.6) Gde poluchit' podderzhku?
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1.7) Kakaya poslednyaya versiya?
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1.8) Kakaya dokumentaciya imeetsya v nalichii?
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1.9) Kak najti informaciyu ob izvestnyh oshibkah ili otsutstvuyuschih
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vozmozhnostyah?
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1.10) Kak nauchit'sya SQL?
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1.11) Reshena li v PostgreSQL problema 2000-go goda (Y2K)?
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1.12) Kak prisoedinitsya k komande razrabotchikov?
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2003-04-01 11:10:44 +08:00
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1.13) Kak otpravit' soobschenie ob oshibke?
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2002-11-11 03:48:41 +08:00
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1.14) Kak sravnivat' PostgreSQL s drugimi SUBD?
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1.15) Kak okazat' finansovuyu pomosch' PostgreSQL?
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Voprosy pol'zovatelej po klientskoj chasti
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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2.1) Suschestvuyut li ODBC drajvera dlya PostgreSQL?
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2.2) Kakie instrumenty suschestvuyut dlya ispol'zovaniya PostgreSQL
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cherez Web?
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2.3) Est' li u PostgreSQL graficheskij interfejs pol'zovatelya?
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2.4) Kakie yazyki mogut vzaimodejstvovat' s PostgreSQL?
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Voprosy administrirovaniya
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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3.1) Kak mne ustanovit' PostgreSQL v mesto otlichnoe ot
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2002-04-12 17:17:10 +08:00
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/usr/local/pgsql?
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2002-11-11 03:48:41 +08:00
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3.2) Kogda ya zapuskayu postmaster, ya poluchayu soobschenie Bad
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System Call ili soobschenie core dumped. Pochemu?
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3.3) Kogda ya pytayus' zapustit' postmaster, ya poluchayu oshibki
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IpcMemoryCreate. Pochemu?
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3.4) Kogda ya pytayus' zapustit' postmaster, ya poluchayu oshibki
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IpcSemaphoreCreate. Pochemu?
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3.5) Kak mne upravlyat' soedineniyami s drugih komp'yuterov?
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3.6) Kakie nastrojki mne nuzhno sdelat' dlya uluchsheniya
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proizvoditel'nosti?
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3.7) Kakie vozmozhnosti dlya otladki est' v nalichii?
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3.8) Pochemu ya poluchayu soobschenie "Sorry, too many clients" kogda
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pytayus' podklyuchit'sya k baze?
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3.9) CHto nahoditsya v kataloge pgsql_tmp?
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3.10) Pochemu neobhodimo delat' dump i restore pri obnovlenii vypuskov
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2002-08-23 10:53:20 +08:00
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PostgreSQL?
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Voprosy `ekspluatacii
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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4.1) V chem otlichie mezhdu binarnym i normal'nym kursorom?
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4.2) Kak vypolnit' SELECT tol'ko dlya neskol'kih pervyh strochek
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zaprosa?
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4.3) Kak poluchit' spisok tablic ili drugih komponentov v psql?
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4.4) Kak udalit' kolonku iz tablicy?
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4.5) Kakovy maksimal'nye razmery dlya zapisej, tablic i bazy dannyh?
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4.6) Kak mnogo diskovogo prostranstva v baze dannyh nuzhno dlya
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sohraneniya dannyh iz obychnogo tekstovogo fajla?
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4.7) Kak mne ubedit'sya, chto suschestvuyut nuzhnye mne tablicy,
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indeksy, bazy dannyh i pol'zovateli?
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4.8) U menya medlenno rabotayut zaprosy ili ne proishodit
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ispol'zovaniya indeksov. Pochemu?
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4.9) Kak posmotret' na to, kak optimizator vypolnyaet moj zapros?
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4.10) CHto takoe R-tree indeks?
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4.11) CHto takoe Genetic Query Optimizer?
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4.12) Kak mne vypolnit' poisk regulyarnogo vyrazheniya i poisk
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nezavisimyj ot registra bukv poisk regulyarnogo vyrazheniya? Kak mne
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ispol'zovat' indeks dlya poiska nezavisimogo ot registra bukv?
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4.13) Kak ya mogu opredelit', chto znachenie polya ravno NULL v
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kakom-libo zaprose?
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4.14) Kakovy otlichiya mezhdu raznymi simvol'nymi tipami?
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4.15.1) Kak mne sozdat' pole serial/s-avto-uvelicheniem?
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4.15.2) Kak mne poluchit' znachenie pri vstavke SERIAL?
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4.15.3) Ne mozhet li poluchit'sya tak, chto ispol'zovanie currval() i
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nextval() privedet k zaciklirovaniyu s drugimi pol'zovatelyami?
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4.15.4) Pochemu chisla iz moej posledovatel'nosti ne ispol'zuyutsya
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snova pri otmene tranzakcii? Pochemu sozdayutsya razryvy pri numeracii
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v kolonke, gde ya ispol'zuyu posledovatel'nost'/SERIAL?
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4.16) CHto takoe OID? CHto takoe TID?
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4.17) CHto oznachayut nekotorye terminy ispol'zuemye v PostgreSQL?
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4.18) Pochemu ya poluchayu oshibku "ERROR: Memory exhausted in
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2002-04-12 17:17:10 +08:00
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AllocSetAlloc()"?
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2002-11-11 03:48:41 +08:00
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4.19) Kak mne uznat', kakaya versiya PostgreSQL zapuschena?
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4.20) Pochemu pri rabote s moim bol'shim ob"ektom ya poluchayu oshibku
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2002-04-12 17:17:10 +08:00
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"invalid large obj descriptor"?
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2002-11-11 03:48:41 +08:00
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4.21) Kak mne sozdat' kolonku kotoraya po umolchaniyu budet soderzhat'
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tekuschee vremya?
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4.22) Pochemu moi podzaprosy, ispol'zuyuschie IN tak medlenno
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rabotaeyut?
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4.23) Kak vypolnit' vneshnee svyazyvanie?
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4.24) Kak vypolnyat' zaprosy, ispol'zuyuschie neskol'ko baz dannyh?
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4.25) Kak mne vernut' iz funkcii neskol'ko zapisej?
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4.26) Pochemu ya ne mogu nadezhno sozdavat'/udalyat' vremennye tablicy
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v funkciyah PL/PgSQL?
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4.27) Kakie opcii replikacii suschestvuyut?
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4.28) Kakie opcii shifrovaniya suschestvuyut?
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Rasshireniya PostgreSQL
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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5.1) YA napisal funkciyu opredelyaemuyu pol'zovatelem. Kogda ya
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zapuskayu ee v psql, pochemu ya poluchayu dump core?
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5.2) Kak ya mogu vnesti nekotorye klassnye novye tipy i funkcii v
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2002-04-12 17:17:10 +08:00
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PostgreSQL?
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2002-11-11 03:48:41 +08:00
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5.3) Kak mne napisat' C funkciyu, vozvraschayuschuyu zapis'?
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5.4) YA izmenil ishodnyj fajl. Pochemu posle perekompilyacii ya ne
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vizhu izmenenij?
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2002-04-12 17:17:10 +08:00
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_________________________________________________________________
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2002-11-11 03:48:41 +08:00
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Obschie voprosy
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.1) CHto takoe PostgreSQL? Kak proiznositsya `eto nazvanie?
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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PostgreSQL proiznositsya Post-Gres-Q-L (Post-Gres-K'yu-`El).
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PostgreSQL - `eto rasshirenie SUBD POSTGRES, issledovatel'skij
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prototip novogo pokoleniya SUBD. PostgreSQL odnovremenno sohranyaet
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moschnuyu model' dannyh i obschirnoe kolichestvo tipov POSTGRES, i
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zameschaet yazyk zaprosov PostQuel na rasshirennoe podmnozhestvo SQL.
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PostgreSQL - `eto svobodnoe i polnost'yu otkrytoe programmnoe
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obespechenie.
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Razrabotku PostgreSQL vypolnyaet komanda razrabotchikov, vse
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uchastniki kotoroj podpisany na spisok rassylki razrabotchikov. V
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nastoyaschee vremya, ih koordinatorom yavlyaetsya Mark Fornaj (Marc G.
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Fournier) (scrappy@PostgreSQL.org). (Sm. sekciyu 1.6 o tom, kak
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podklyuchit'sya k razrabotke). `Eta komanda teper' otvechaet za vsyu
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razrabotku PostgreSQL.
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Avtorami PostgreSQL 1.01 yavlyayutsya `Endryu YU (Andrew Yu) i Dzholi
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CHen (Jolly Chen). Mnogie drugie vnesli svoj vklad v perenos na drugie
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platformy, testirovanie, otladku i rasshirenie `etogo koda.
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Pervonachal'nyj kod Postgres, iz kotorogo poyavilsya PostgreSQL, byl
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itogom usilij mnogih akademicheskih studentov, neakademicheskih
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studentov i mnozhestva raznyh programmistov, rabotavshih pod
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rukovodstvom professora Majkla Stounbrejkera (Michael Stonebraker) v
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Kalifornijskom universitete, Berkli.
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Pervonachal'noe imya, dannoe v Berkli, bylo Postgres. Kogda v 1995
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godu byla dobavlena funkcional'nost' SQL, `eto imya bylo izmeneno na
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Postgres95. No i `eto imya bylo izmeneno v konce 1996 na PostgreSQL.
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1.2) Kakovy avtorskie prava na PostgreSQL?
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PostgreSQL popadaet pod dejstvie sleduyuschego COPYRIGHT:
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Sistema Upravleniya Bazami Dannyh PostgreSQL
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Portion copyright (c) 1996-2002, PostgreSQL Global Development Group
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Portions Copyright (c) 1994-6 Regents of the University of California
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Predostavlyayutsya prava na ispol'zovanie, kopirovanie, izmenenie i
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rasprostranenie dannogo programmnogo obespecheniya i ego dokumentacii
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dlya lyubyh celej, besplatno i bez podpisaniya kakogo-libo
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soglasheniya, pri uslovii chto dlya kazhdoj kopii budut predostavleny
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dannoe vyshe zamechanie ob avtorskih pravah, tekuschij paragraf i dva
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sleduyuschih paragrafa.
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KALIFORNIJSKIJ UNIVERSITET NE NESET NIKAKOJ OTVETSTVENNOSTI ZA LYUBYE
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POVREZHDENIYA, VKLYUCHAYA POTERYU DOHODA, NANESENNYE PRYAMYM ILI
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NEPRYAMYM, SPECIAL'NYM ILI SLUCHAJNYM ISPOL'ZOVANIEM DANNOGO
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PROGRAMMNOGO OBESPECHENIYA ILI EGO DOKUMENTACII, DAZHE ESLI
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KALIFORNIJSKIJ UNIVERSITET BYL IZVESCHEN O VOZMOZHNOSTI TAKIH
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POVREZHDENIJ.
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KALIFORNIJSKIJ UNIVERSITET SPECIAL'NO OTKAZYVAZYVAETSYA PREDOSTAVLYAT'
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LYUBYE GARANTII, VKLYUCHAYA, NO NE OGRANICHIVAYAS' TOL'KO `ETIMI
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GARANTIYAMI: NEYAVNYE GARANTII PRIGODNOSTI TOVARA ILI PRIGODNOSTI DLYA
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OTDEL'NOJ CELI. DANNOE PROGRAMMNOE OBESPECHENIE PREDOSTAVLYAETSYA NA
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OSNOVE PRICIPA "KAK EST'" I KALIFORNIJSKIJ UNIVERSITET NE OBYAZAN
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PREDOSTAVLYAT' SOPROVOZHDENIE, PODDERZHKU, OBNOVLENIYA, RASSHIRENIYA
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ILI IZMENENIYA.
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Vysheizlozhennoe yavlyaetsya BSD licenziej, klassicheskoj licenziej
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programmnogo obespecheniya s otkrytym kodom. `Eta licenziya ne
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nakladyvaet ogranichenij na ispol'zovanie ishodnogo koda. Nam
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nravitsya `eta licenziya i my ne sobiraemsya eio menyat'.
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1.3) Na kakih Unix platformah rabotaet PostgreSQL?
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Obychno, PostgreSQL mozhet rabotat' na lyuboj sovremennoj platforme
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sovmestimoj s Unix. V instrukcii po ustanovke, vy najdete spisok teh
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platform, na kotoryh byli provedeny testovye zapuski PostgreSQL k
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momentu vyhoda dannoj versii.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.4) Suschestvuyut li versii perenesennye ne na Unix sistemy?
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Klient
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Dlya zapuska na platformah MS Windows vozmozhna kompilyaciya C
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biblioteki libpq, psql, drugih interfesov i klientskih prilozhenij. V
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`etom sluchae, klient zapuskaetsya na MS Windows i svyazyvaetsya po
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TCP/IP s serverom, zapuschennym na odnoj iz podderzhivaemyh Unix
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platform. V distributiv vklyuchaetsya fajl win32.mak dlya togo, chtoby
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mozhno bylo provesti sborku biblioteki libpq i psql dlya Win32.
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PostgreSQL takzhe rabotaet cherez ODBC.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Server
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Server BD mozhet byt' zapuschen na Windows NT i Win2k, ispol'zuya
|
2003-06-03 00:39:06 +08:00
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biblioteku Cygwin, razrabotannuyu kompaniej Cygnus dlya perenosa
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programmnogo obespecheniya Unix v NT. Smotrite pgsql/doc/FAQ_MSWIN v
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distributive ili MS Windows FAQ na
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http://www.PostgreSQL.org/docs/faqs/text/FAQ_MSWIN.
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2002-11-11 03:48:41 +08:00
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PostgreSQL, sportirovannyj special'no dlya MS Win NT/2000/XP v
|
2003-06-03 00:39:06 +08:00
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nastoyaschij moment nachal rabotat'. Podrobnosti tekuschego
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sostoyaniya PostgreSQL dlya Windows smotrite na
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http://techdocs.postgresql.org/guides/Windows.
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Takzhe suschestvuet versiya sportirovannaya pod Novell Netware 6 na
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http://forge.novell.com.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.5) Gde mozhno vzyat' PostgreSQL?
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Naprimer, vospol'zovavshis' anonimnym dostupom na ftp sajt PostgreSQL
|
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ftp://ftp.PostgreSQL.org/pub. Spisok zerkal vy najdete na nashem
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osnovnom sajte.
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1.6) Gde poluchit' podderzhku?
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Osnovnoj spisok rassylki: pgsql-general@PostgreSQL.org. V nem mozhno
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obsuzhdat' lyubye temy, kasayuschiesya PostgreSQL. CHtoby
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podpisat'sya, otprav'te pis'mo po `elektronnoj pochte, v kotorom v
|
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tele pis'ma (ne v teme) napishite sleduyuschie stroki:
|
2002-04-12 17:17:10 +08:00
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subscribe
|
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end
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2002-11-11 03:48:41 +08:00
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na adres pgsql-general-request@PostgreSQL.org.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Suschestvuet dajzhest spisok. CHtoby podpisat'sya na nego, otprav'te
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pis'mo po `elektronnoj pochte na adres:
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pgsql-general-digest-request@PostgreSQL.org i v tele pis'ma napishite
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strochki strochki:
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2002-04-12 17:17:10 +08:00
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subscribe
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end
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2002-11-11 03:48:41 +08:00
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Dajzhesty otpravlyayutsya podpischikam, kogda v osnovnom spiske
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rassylki nakopitsya okolo 30 kilobajt soobschenij.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Dostupen i spisok rassylki soobschenij ob oshibkah. CHtoby
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podpisat'sya na `etot spisok, otprav'te po `elektronnoj pochte pis'mo
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na adres pgsql-bugs-request@PostgreSQL.org i v tele pis'ma napishite
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strochki strochki:
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2002-04-12 17:17:10 +08:00
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subscribe
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end
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2002-11-11 03:48:41 +08:00
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Takzhe imeetsya spisok rassylki s diskussiyami razrabotchikov. CHtoby
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podpisat'sya na `etot spisok, otprav'te po `elektronnoj pochte pis'mo
|
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na adres pgsql-hackers-request@PostgreSQL.org i v tele pis'ma
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napishite strochki strochki:
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2002-04-12 17:17:10 +08:00
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subscribe
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end
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2002-11-11 03:48:41 +08:00
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Dopolnitel'nye spiski rassylki i infomaciyu o PostgreSQL mozhno najti
|
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na domashnej stranichke PostgreSQL po adresu:
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2002-04-12 17:17:10 +08:00
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http://www.PostgreSQL.org
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2003-06-03 00:39:06 +08:00
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Esche suschestvuet IRC kanal na EFNet i OpenProjects, s nazvaniem
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#PostgreSQL. YA ispol'zuyu dlya podklyucheniya k `etomu kanalu komandu
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Unix irc -c '#PostgreSQL' "$USER" irc.phoenix.net.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Spisok kommercheskoj podderzhki kompanij dostupen na
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2003-03-07 13:46:51 +08:00
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http://www.ca.PostgreSQL.org/users-lounge/commercial-support.html.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.7) Kakaya poslednyaya versiya?
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2002-04-12 17:17:10 +08:00
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2003-03-07 13:46:51 +08:00
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Poslednij vypusk PostgreSQL - `eto versiya 7.3.2.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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My planiruem vypuskat' novye versii kazhdye chetyre mesyaca.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.8) Kakaya dokumentaciya imeetsya v nalichii?
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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V distributiv vklyuchayutsya razlichnye rukovodstva, stranicy
|
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`elektronnogo rukovodstva man i nekotorye malen'kie testovye primery.
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Smotrite v katalog /doc. Vy takzhe mozhete prosmatrivat' dokumentaciyu
|
2003-06-03 00:39:06 +08:00
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v Internet po adresu http://www.PostgreSQL.org/docs.
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2002-11-11 03:48:41 +08:00
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Suschestvuet dve knigi po PostgreSQL dostupnye po adresam
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http://www.PostgreSQL.org/docs/awbook.html i
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http://www.commandprompt.com/ppbook/. Spisok knig po PostgreSQL,
|
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kotorye mozhno kupit' dostupen po adresu
|
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http://www.ca.PostgreSQL.org/books/. Krome togo, po adresu
|
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http://techdocs.PostgreSQL.org/ vy mozhete najti kollekciyu
|
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tehnicheskih statej posvyaschennyh PostgreSQL.
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psql imeet neskol'ko prekrasnyh komand \d dlya otobrazheniya
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informacii po tipam, operatoram, funkciyam, agregatam i t.d.
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Nash sajt soderzhit esche bol'she informacii.
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1.9) Kak najti informaciyu ob izvestnyh oshibkah ili otsutstvuyuschih
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vozmozhnostyah?
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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PostgreSQL podderzhivaet rasshirennyj podklass SQL-92. Smotrite nash
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spisok TODO na predmet izvestnyh oshibok, otsutstvuyuschih
|
2003-04-01 11:10:44 +08:00
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vozmozhnostej i buduschih planov.
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.10) Kak mne nauchit'sya SQL?
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Kniga po PostgreSQL na http://www.PostgreSQL.org/docs/awbook.html
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nauchit SQL. Suschestvuet drugaya kniga po PostgreSQL na
|
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http://www.commandprompt.com/ppbook. Est' prekrasnyj uchebnik na
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http://www.intermedia.net/support/sql/sqltut.shtm, na
|
2002-04-12 17:17:10 +08:00
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http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM,
|
2002-11-11 03:48:41 +08:00
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i na http://sqlcourse.com.
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
|
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Esche odin uchebnik - `eto kniga "Teach Yourself SQL in 21 Days,
|
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|
|
Second Edition" (Osvoj samostoyatel'no SQL za 21 den', Vtoraya
|
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|
redakciya) na http://members.tripod.com/er4ebus/sql/index.htm
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Mnogim iz nashih pol'zovatelej nravitsya kniga The Practical SQL
|
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Handbook, Bowman, Judith S., et al., Addison-Wesley. Drugim nravitsya
|
2002-04-12 17:17:10 +08:00
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The Complete Reference SQL, Groff et al., McGraw-Hill.
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2002-11-11 03:48:41 +08:00
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1.11) Reshena li v PostgreSQL problema 2000-go goda (Y2K)?
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2002-04-12 17:17:10 +08:00
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2003-04-01 11:10:44 +08:00
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Da, my legko rabotaem s datami posle 2000 goda i pered 2000 godom.
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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1.12) Kak prisoedinitsya k komande razrabotchikov?
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2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Dlya nachala, skachajte poslednyuyu versiyu ishodnyh tekstov i
|
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|
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prochtite dokumentaciyu razrabotchikov PostgreSQL na nashem sajte ili
|
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v distributive. Zatem, podpishites' na spiski rassylki pgsql-hackers i
|
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|
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pgsql-patches. Dalee, otpravlyajte ispravleniya (patches) vysokogo
|
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kachestva v spisok pgsql-patches.
|
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Suschestvuet ogranichennyj spisok lyudej, kotoryj imeyut privelegiyu
|
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vnosit' izmeneniya v CVS arhiv PostgreSQL. Kazhdyj iz `etih lyudej v
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svoe vremya otpravil tak mnogo vysokokachestvennyh ispravlenij, chto
|
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ih bylo nevozmozhno ostavit' bez vnimaniya i oni byli udostoeny
|
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previlegii vnosit' izmeneniya, i my uvereny, chto te ispravleniya,
|
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kotorye oni vnesut budut vysokogo kachestva.
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2003-04-01 11:10:44 +08:00
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1.13) Kak otpravit' soobschenie ob oshibke??
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
|
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Pozhalujsta posetite stranichku PostgreSQL BugTool na
|
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http://www.PostgreSQL.org/bugs/bugs.php, na kotoroj predostavleny
|
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|
|
detal'nye instrukcii o tom kak otpravit' soobschenie ob oshibke.
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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Takzhe ne zabud'te posmotret' na ftp://ftp.PostgreSQL.org/pub na
|
|
|
|
predmet bolee svezhih versij PostgreSQL ili zaplat.
|
2002-04-12 17:17:10 +08:00
|
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2002-11-11 03:48:41 +08:00
|
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1.14) Kak sravnivat' PostgreSQL s drugimi SUBD?
|
2002-04-12 17:17:10 +08:00
|
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2002-11-11 03:48:41 +08:00
|
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Suschestvuet neskol'ko metodov sravneniya programmnogo obespecheniya:
|
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vozmozhnosti, proizvoditel'nost', nadezhnost', podderzhka i cena.
|
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Vozmozhnosti
|
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|
PostgreSQL imeet bol'shinstvo vozmozhnostej predstavlennyh v
|
|
|
|
bol'shih kommercheskih SUBD, takie kak: tranzakcii, podzaprosy,
|
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|
|
triggery, obzory (views), vneshnij klyuch ssylochnoj
|
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celostnosti i raznye blokirovki. U nas est' nekotorye
|
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vozmozhnosti, kotoryh net u nih: tipy, opredelyaemye
|
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|
pol'zovatelem, mehanizm nasledovaniya, pravila i konkuretnoe
|
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|
|
mnogoversionnoe upravlenie dlya raboty s soderzhimym
|
|
|
|
blokirovok.
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
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|
Proizvoditel'nost'
|
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|
|
PostgreSQL imeet proizvoditel'nost' shozhuyu s drugimi
|
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|
|
kommercheskimi SUBD i s SUBD s otkrytym ishodnym kodom, v
|
|
|
|
kakih-to aspektah rabotaya bystree chem oni, v kakih-to
|
|
|
|
medlenee. V sravnenii s MySQL ili linejnymi SUBD, my medlenee
|
|
|
|
pri operaciyah vstavki/obnovleniya, potomu chto upravlyaem
|
|
|
|
tranzakciyami. I razumeetsya, MySQL ne imeet kakih-libo
|
|
|
|
vozmozhnostej iz perechislenyh vyshe, v sekcii Vozmozhnosti. My
|
|
|
|
delaem upor na nadezhnost' i rasshirennye vozmozhnosti, no my
|
|
|
|
takzhe prodolzhaem uvelichivat' proizvoditel'nost' s kazhdym
|
|
|
|
vypuskom. Suschestvuet interesnaya stranichka v Internet,
|
|
|
|
sravnivayuschaya PostgreSQL i MySQL na
|
|
|
|
http://openacs.org/philosophy/why-not-mysql.html
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
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Nadezhnost'
|
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My ponimali, chto nasha SUBD dolzhna byt' nadezhnoj ili ona
|
|
|
|
nichego ne budet stoit'. My staraemsya vypuskat' horosho
|
|
|
|
proverennyj, stabil'nyj kod, kotoryj soderzhit minimum oshibok.
|
|
|
|
Kazhdyj vypusk prohodit stadiyu beta-testirovaniya po krajnej
|
|
|
|
mere v techenii odnogo mesyaca i nasha istoriya vypuskov
|
|
|
|
pokazyvaet chto my mozhem predostavlyat' stabil'nye, monolitnye
|
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|
|
vypuski, kotorye gotovy k produktivnomu ispol'zovaniyu. My
|
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verim, chto my proizvodim proverku ne huzhe, chem u drugih
|
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SUBD.
|
2002-04-12 17:17:10 +08:00
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|
2002-11-11 03:48:41 +08:00
|
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Podderzhka
|
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|
Nash spisok rassylki predostavlyaet vozmozhmozhnost' obscheniya
|
|
|
|
s bol'shoj gruppoj razrabotchikov i pol'zovatelej, kotorye
|
|
|
|
mogut pomoch' reshit' lyubye voznikshie problemy. V to zhe
|
|
|
|
vremya, my ne garantiruem kakie-libo ispravleniya, no i
|
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|
|
razrabotchiki kommercheskih SUBD ne vsegda delayut
|
|
|
|
ispravleniya. Pryamoj dostup k razrabotchikam, soobschestvu
|
|
|
|
pol'zovatelej, rukovodstvam i ishodnym tekstam chasto delayut
|
|
|
|
podderzhku PostgreSQL prevoshodyaschej drugie SUBD.
|
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|
|
Suschestvuet kommercheskaya podderzhka po rezul'tam voznikshih
|
|
|
|
incidentov, kotoraya dostupna dlya teh komu ona nuzhna.
|
|
|
|
(Smotrite Sekciyu 1.6.)
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
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Cena
|
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|
Nash produkt besplaten kak dlya kommercheskogo tak, i ne dlya
|
|
|
|
kommercheskogo ispol'zovaniya. Vy mozhete dobavlyat' svoj kod v
|
|
|
|
nash produkt bez ogranichenij, za isklyucheniem teh, chto
|
|
|
|
opisyvayutsya v nashej licenzii stilya BSD, kotoraya privedena
|
|
|
|
vyshe.
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
1.15) Kak okazat' finansovuyu pomosch' PostgreSQL?
|
|
|
|
|
|
|
|
PostgreSQL imeet odnorangovuyu infrastrukturu s togo samogo vremeni
|
|
|
|
kak my nachali razrabotku v 1996 godu. My dolzhny blagodarit' za `eto
|
|
|
|
Marka Fonaya (Marc Fournier), kotoryj sozdal `etu infrastrukturu i
|
|
|
|
upravlyaet ej na protyazhenii `etih let.
|
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|
|
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|
|
Kachestvennaya infrastruktura ochen' vazhna dlya proektov s otkrytym
|
|
|
|
ishodnym kodom. Ona predotvraschaet raskoly, kotorye mogut sil'no
|
|
|
|
zaderzhat' postupatel'noe dvizhenie proekta.
|
|
|
|
|
|
|
|
Razumeetsya, `eta infrastruktura ne yavlyaetsya deshevoj. Suschestvuet
|
|
|
|
nekotoroe kolichestvo ezhemesyachnyh i odnorazovyh rashodov, kotorye
|
|
|
|
trebuyut deneg. Esli vy ili vasha kompaniya imeet den'gi, kotorye
|
|
|
|
mozhno peredat' v pomosch' nashim usiliyam, pozhalujsta posetite
|
|
|
|
stranichku https://store.pgsql.com/shopping/ i sdelajte svoj vklad.
|
|
|
|
|
|
|
|
Hotya na stranichke govoritsya o PostgreSQL, Inc, punkt
|
|
|
|
"contributions" prednaznachen isklyuchitel'no dlya podderzhki proekta
|
|
|
|
PostgreSQL i ne peredaetsya kakoj-libo konkretnoj kompanii. Esli
|
|
|
|
hotite, to mozhete `eto proverit', napisav pis'mo na kontaktnyj adres.
|
2002-04-12 17:17:10 +08:00
|
|
|
_________________________________________________________________
|
|
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|
|
2002-11-11 03:48:41 +08:00
|
|
|
Voprosy pol'zovatelej po klientskoj chasti
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
2.1) Suschestvuyut li ODBC drajvera dlya PostgreSQL?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Suschestvuet dva ODBC drajvera, PsqlODBC i OpenLink ODBC.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-12-19 04:38:48 +08:00
|
|
|
Vy mozhete skachat' PsqlODBC s
|
|
|
|
http://gborg.postgresql.org/project/psqlodbc/projdisplay.php.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
OpenLink ODBC mozhno vzyat' na http://www.openlinksw.com. `Etot
|
|
|
|
drajver rabotaet s ih standartnym klientskim programmnym
|
|
|
|
obespecheniem, ispol'zuyuschim ODBC, i takim obrazom, ODBC drajvery
|
|
|
|
dlya PostgreSQL dostupny dlya kazhdoj iz podderzhivaemyh imi platform
|
|
|
|
(Win, Mac, Unix, VMS).
|
2002-04-12 17:17:10 +08:00
|
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|
|
2002-11-11 03:48:41 +08:00
|
|
|
Vozmozhno oni budut prodavat' svoj produkt tem komu nuzhna
|
|
|
|
kommercheskaya podderzhka, no besplatnaya versiya vsegda budet
|
|
|
|
dostupna. Pozhalujsta, napravlyajte voprosy na adres
|
|
|
|
postgres95@openlink.co.uk.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
2.2) Kakie instrumenty suschestvuyut dlya ispol'zovaniya PostgreSQL cherez
|
|
|
|
Web?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Prekrasnoe vvedenie vo vzaimodejstvie baz dannyh i Web mozhno najti
|
|
|
|
na: http://www.webreview.com
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Dlya integracii s Web, odnim iz prevoshodnyh instrumentov yavlyaetsya
|
|
|
|
PHP. Domashnyaya stanichka http://www.php.net.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Dlya kompleksnyh reshenij, mnogie pol'zuyutsya Perl interfejsom i
|
|
|
|
CGI.pm ili mod_perl.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-12-19 04:38:48 +08:00
|
|
|
2.3) Est' li u PostgreSQL graficheskij interfejs pol'zovatelya?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-12-19 04:38:48 +08:00
|
|
|
Da, suschestvuet neskol'ko graficheskih interfejsov dlya PostgreSQL.
|
2003-02-14 22:05:00 +08:00
|
|
|
`Eto PgAccess (http://www.pgaccess.org, PgAdmin II
|
2002-12-19 04:38:48 +08:00
|
|
|
(http://www.pgadmin.org, Win32-only), RHDB Admin (
|
|
|
|
http://sources.redhat.com/rhdb/) i Rekall (
|
|
|
|
http://www.thekompany.com/products/rekall/, kommercheskij). Takzhe
|
|
|
|
est' PHPPgAdmin ( http://phppgadmin.sourceforge.net/) - interfejs k
|
|
|
|
PostgreSQL, osnovannyj na Web.
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
2.4) Kakie yazyki mogut vzaimodejstvovat' s PostgreSQL?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-12-19 04:38:48 +08:00
|
|
|
Kakie-libo interfejsy dlya PostgreSQL suschestvuyut dlya bol'shinstva
|
|
|
|
populyarnyh yazykov programmirovaniya. Posmotrite spisok modulej
|
|
|
|
rasshireniya dlya teh yazykov programmirovaniya, kotorymi vy
|
|
|
|
pol'zuetes'.
|
|
|
|
|
|
|
|
Sleduyuschie interfejsy vklyuchayutsya v distributiv PostgreSQL:
|
2002-04-12 17:17:10 +08:00
|
|
|
* C (libpq)
|
|
|
|
* Embedded C (ecpg)
|
|
|
|
* Java (jdbc)
|
|
|
|
* Python (PyGreSQL)
|
|
|
|
* TCL (libpgtcl)
|
2002-08-23 10:53:20 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Dopolnitel'nye interfejsy dostupny po adresu
|
2002-12-19 04:38:48 +08:00
|
|
|
http://gborg.PostgreSQL.org v sekcii Drivers/Interfaces.
|
2002-04-12 17:17:10 +08:00
|
|
|
_________________________________________________________________
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Voprosy administrirovaniya
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
3.1) Kak mne ustanovit' PostgreSQL v mesto otlichnoe ot /usr/local/pgsql?
|
|
|
|
|
|
|
|
Zadajte opciyu --prefix kogda zapuskaete configure.
|
|
|
|
|
|
|
|
3.2) Kogda ya zapuskayu postmaster, ya poluchayu soobschenie Bad System
|
|
|
|
Call ili soobschenie core dumped. Pochemu?
|
|
|
|
|
|
|
|
`Eto mozhet byt' vyzvano raznymi problemami, no pervoe, chto nuzhno
|
|
|
|
sdelat' - `eto ubedit'sya v tom, chto v vashem yadre ustanovleno
|
|
|
|
rasshirenie System V. PostgreSQL trebuet, chtoby yadro podderzhivalo
|
|
|
|
razdelyaemuyu pamyat' i semafory.
|
|
|
|
|
|
|
|
3.3) Kogda ya pytayus' zapustit' postmaster, ya poluchayu oshibki
|
|
|
|
IpcMemoryCreate. Pochemu?
|
|
|
|
|
|
|
|
Libo u vas v yadre nepravil'nye nastrojki razdelyaemoj pamyati, libo
|
|
|
|
vashemu yadru nuzhno bol'shee kolichestvo dostupnoj razdelyaemoj
|
|
|
|
pamyati. Te konkretnye dejstviya, kotorye vam nuzhno proizvesti
|
|
|
|
zavisyat ot arhitektury vashej mashiny i ot togo kak mnogo buferov i
|
|
|
|
backend processov vy nastroili dlya postmaster. Dlya bol'shinstva
|
|
|
|
sistem, s kolichestvom buferov i processov po umolchaniyu, neobhodimyj
|
|
|
|
minimum - `eto okolo 1 megabajta. Podrobnosti o razdelyaemoj pamyati i
|
|
|
|
semaforah smotrite v Rukovodstve administratora PostgreSQL.
|
|
|
|
|
|
|
|
3.4) Kogda ya pytayus' zapustit' postmaster, ya poluchayu oshibki
|
|
|
|
IpcSemaphoreCreate. Pochemu?
|
|
|
|
|
|
|
|
Esli `eto soobschenie IpcSemaphoreCreate: semget failed (No space left
|
|
|
|
on device) to nastrojki vashego yadra takovy, chto emu ne hvataet
|
|
|
|
semaforov. Postgres trebuet odin semafor na potencial'nyj backend
|
|
|
|
process. Vremennym resheniem yavlyaetsya zapusk postmaster s
|
|
|
|
nastrojkami na mesh'shee kolichestvo backend processov. Ispol'zujte -N
|
|
|
|
s znacheniem men'shim chem 32, kotoroe prinyato po umolchaniyu. Bolee
|
|
|
|
pravil'noe reshenie - `eto uvelichit' znacheniya SEMMNS i SEMMNI v
|
|
|
|
nastrjkah yadra.
|
|
|
|
|
|
|
|
Neispravnye semafory takzhe mogut privesti k padeniyu SUBD vo vremya
|
|
|
|
dostupa k baze dannyh.
|
|
|
|
|
|
|
|
Esli vy poluchili kakoe-libo drugoe soobschenie ob oshibke, to vpolne
|
|
|
|
vozmozhno, chto v vashem yadre voobsche ne nastroena podderzhka
|
|
|
|
semaforov. Smotrite podrobnosti o razdelyaemoj pamyati i semaforah v
|
|
|
|
Rukovodstve Administratora PostgreSQL.
|
|
|
|
|
|
|
|
3.5) Kak mne upravlyat' soedineniyami s drugih komp'yuterov?
|
|
|
|
|
|
|
|
Po umolchaniyu, PostgreSQL razreshaet tol'ko soedineniya na lokal'noj
|
|
|
|
mashine cherez sokety domena Unix. Drugie mashiny ne smogut
|
|
|
|
podklyuchit'sya k baze poka dlya postmaster ne budet zadan flag -i i
|
|
|
|
poka ne budet razreshena host-avtorizaciya v fajle
|
|
|
|
$PGDATA/pg_hba.conf. `Eti dejstviya delayut vozmozhnymi TCP/IP
|
|
|
|
soedineniya.
|
|
|
|
|
|
|
|
3.6) Kakie nastrojki mne nuzhno sdelat' dlya uluchsheniya
|
|
|
|
proizvoditel'nosti?
|
|
|
|
|
|
|
|
Nesomnenno, indeksy mogut uvelichit' skorost' vypolneniya zaprosov.
|
|
|
|
Komanda EXPLAIN pozvolyaet vam posmotret' kak PostgreSQL
|
|
|
|
interpretiruet vash zapros i kakie indeksy ispol'zuyutsya.
|
|
|
|
|
|
|
|
Esli vy vypolnyaete mnogo operatorov INSERT, rassmotrite vozmozhnost'
|
|
|
|
vypolnyat' ih v bol'shoj pachke, ispol'zuya komandu COPY. `Eto
|
|
|
|
znachitel'no bystree, chem otdel'nye INSERT. Vo-vtoryh, operatory vne
|
|
|
|
bloka tranzakcii BEGIN WORK/COMMIT sami vypolnyayut tranzakciyu.
|
|
|
|
Podumajte nad vypolneniem neskol'kih operatorov v odnom bloke
|
|
|
|
tranzakcii. `Eto umen'shit kolichestvo tranzakcij. Takzhe, zadumajtes'
|
|
|
|
nad udaleniem i peresozdaniem indeksov, kogda vy vypolnyaete bol'shie
|
|
|
|
izmeneniya dannyh.
|
|
|
|
|
|
|
|
Suschestvuet neskol'ko opcij nastrojki. Vy mozhete zapretit' fsync()
|
|
|
|
pri starte postmaster s opciej -o -F. `Eto predotvratit vyzovy
|
|
|
|
fsync(), kotorye privodyat k sbrosu dannyh na disk posle kazhdoj
|
|
|
|
tranzakcii.
|
|
|
|
|
|
|
|
Vy mozhete takzhe ispol'zovat' dlya postmaster opciyu -B dlya
|
|
|
|
uvelicheniya kolichestva buferov razdelyaemoj pamyati, kotoraya
|
|
|
|
ispol'zuetsya backend processami. Esli vy sdelaete znachenie `etogo
|
|
|
|
parametra slishkom bol'shim, to postmaster mozhet ne zapustitsya
|
|
|
|
potomu chto vy ischerpaete ogranichenie yadra na ob"em razdelyaemoj
|
|
|
|
pamyati. Kazhdyj bufer imeet razmer v 8 kilobajt i po umolchaniyu
|
|
|
|
vydelyaetsya 64 bufera.
|
|
|
|
|
|
|
|
Vy mozhete takzhe ispol'zovat' backend opciyu -S dlya uvelicheniya
|
|
|
|
maksimal'nogo kolichestva pamyati, kotoroe ispol'zuetsya backend
|
|
|
|
processom dlya vremennyh sortirovok. Znachenie dlya opcii -S zadaetsya
|
|
|
|
v kilobajtah i po umolchaniyu ravno 512 (t.e. 512K).
|
|
|
|
|
|
|
|
Vy takzhe mozhete ispol'zovat' komandu CLUSTER dlya gruppirovki dannyh
|
|
|
|
v tablicah na sovpadayuschij indeks. Podrobnosti smotrite na stranice
|
|
|
|
rukovodstva po komande CLUSTER.
|
|
|
|
|
|
|
|
3.7) Kakie vozmozhnosti dlya otladki est' v nalichii?
|
|
|
|
|
|
|
|
PostgreSQL imeet neskol'ko vozmozhnostej, pozvolyayuschie poluchit'
|
|
|
|
informaciyu o sostoyanii, kotoraya mozhet byt' ispol'zovana v
|
|
|
|
otladochnyh celyah.
|
|
|
|
|
|
|
|
Vo-pervyh, pri zapuske configure s opciej --enable-cassert, mnogie
|
|
|
|
vyzovy assert() pozvolyayut otslezhivat' rabotu backend processa i
|
|
|
|
ostanovku programmy pri vozniknovenii kakih-libo neozhidannostej.
|
|
|
|
|
|
|
|
I postmaster, i postgres imeyut neskol'ko otladochnyh opcij.
|
|
|
|
Vo-pervyh, pri zapuske postmaster, ubedites', chto standartnyj vyvod i
|
|
|
|
vyvod oshibok osuschestvlyayutsya v fajl zhurnala:
|
2002-04-12 17:17:10 +08:00
|
|
|
cd /usr/local/pgsql
|
|
|
|
./bin/postmaster >server.log 2>&1 &
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
`Eto privedet k poyavleniyu fajla server.log v glavnom kataloge
|
|
|
|
PostgreSQL. `Etot fajl soderzhit poleznuyu informaciyu o problemah ili
|
|
|
|
oshibkah, voznikshih na servere. Postmaster imeet opciyu -d, kotoraya
|
|
|
|
pozvolyaet poluchat' pri protokolirovanii bolee detal'nuyu infrmaciyu.
|
|
|
|
Dlya opcii -d ukazyvaetsya chislo, kotoroe zadaet uroven' otladki.
|
|
|
|
Bud'te ostorozhny, tak kak vysokij uroven' otladki privodit k
|
|
|
|
generacii fajlov zhurnala bol'shogo razmera.
|
|
|
|
|
|
|
|
Esli postmaster ne zapuschen, vy mozhete zapustit' postgres backend iz
|
|
|
|
komandnoj stroki i vvesti vash operator SQL napryamuyu. `Eto
|
|
|
|
rekomenduetsya tol'ko dlya celej otladki. Zametim, chto v `etom
|
|
|
|
rezhime, zapros zavershaetsya simvolom novoj stroki, a ne tochkoj s
|
|
|
|
zapyatoj. Esli vy proizvodili kompilyaciyu s otladochnymi simvoloami,
|
|
|
|
vy mozhete ispol'zovat' lyuboj otladchik, chtoby posmotret', chto
|
|
|
|
sluchilos'. Poskol'ku backend zapuskaetsya ne iz postmaster, on ne
|
|
|
|
zapuskaetsya v identichnom okruzhenii i znachit problemy iteracij
|
|
|
|
blokirovok/backend ne mogut byt' vosproizvedeny.
|
|
|
|
|
|
|
|
Esli postmaster zapuschen, zapustite psql v odnom okne, zatem najdite
|
|
|
|
PID processa postgres, ispol'zuemyj psql. Ispol'zujte otdadchik dlya
|
|
|
|
podklyucheniya k postgres PID. Vy mozhete ustanovit' tochki
|
|
|
|
preryvaniya v otladchike i zapustit' zapros iz psql. Esli vy
|
|
|
|
proizvodite otladku zapuska postgres, vy mozhete ustanovit'
|
|
|
|
PGOPTIONS="-W n", i zatem zapustit' psql. `Eta opciya privodit k
|
|
|
|
zaderzhke processa zapuska na n sekund, v techenie kotoryh vy mozhete
|
|
|
|
podklyuchit' k processu otladchik, ustanovit' lyubye tochki
|
|
|
|
preryvaniya i prodolzhit' zapusk.
|
|
|
|
|
|
|
|
Programma postgres imeet opcii -s, -A, i -t kotorye mogut byt' ochen'
|
|
|
|
poleznymi dlya otladki i izmereniya proizvoditel'nosti.
|
|
|
|
|
|
|
|
Vy takzhe mozhete skompilirovat' PostgreSQL s profilirovaniem dlya
|
|
|
|
togo, chtoby uvidet' kakie funkcii skol'ko vremeni vypolnyayutsya.
|
|
|
|
Fajly profilirovaniya backend'a nahodyatsya v kataloge
|
|
|
|
pgsql/data/base/dbname. Fajl profilirovaniya klienta budet pomeschen v
|
|
|
|
tekuschij katalog klienta. V Linux dlya vypolneniya profilirovaniya
|
|
|
|
trebuetsya kompilyacii s -DLINUX_PROFILE.
|
|
|
|
|
|
|
|
3.8) Pochemu ya poluchayu soobschenie "Sorry, too many clients" kogda
|
|
|
|
pytayus' podklyuchit'sya k baze?
|
|
|
|
|
|
|
|
Vam nuzhno uvelichit' ogranichenie na kolichestvo konkuretnyh backend
|
|
|
|
processov pri zapuske postmaster.
|
|
|
|
|
|
|
|
Po umolchaniyu ustanovlen limit na 32 processa. Vy mozhete uvelichit'
|
|
|
|
`etot limit perezapustiv postmaster s nuzhnym znacheniem processov,
|
|
|
|
kotoroe ukazyvaetsya v opcii -N ili izmeniv fajl postgresql.conf.
|
|
|
|
|
|
|
|
Zametim, chto esli vy zadadite v opcii -N znachenie bol'she 32, to vy
|
|
|
|
takzhe dolzhny uvelichit' znachenie v opcii -B kotoroe po umolchaniyu
|
|
|
|
ustanovleno v 64; Znachenie opcii -B dolzhno byt' po krajnej mere
|
|
|
|
vdvoe bol'she znacheniya opcii -N, i vozmozhno eschio bol'she dlya
|
|
|
|
luchshej proizvoditel'nosti. Dlya bol'shego kolichestva backend
|
|
|
|
processov, vam takzhe neploho bylo by uvelichit' nekotorye parametry
|
|
|
|
yadra Unix. `Eto takie parametry, kak maksimal'noe kolichestvo blokov
|
|
|
|
razdelyaemoj pamyati, SHMMAX; maksimal'noe kolichestvo semaforov,
|
|
|
|
SEMMNS i SEMMNI; maksimal'noe kolichestvo processov, NPROC;
|
|
|
|
maksimal'noe kolichestvo processov na pol'zovatelya, MAXUPRC; i
|
|
|
|
maksimal'noe kolichestvo otkrytyh fajlov, NFILE i NINODE. Prichina
|
|
|
|
sozdaniya ogranicheniya na kolichestvo backend processov kak raz i
|
|
|
|
sostoit v tom, chtoby vashej sisteme hvatilo resursov.
|
|
|
|
|
|
|
|
3.9) CHto nahoditsya v kataloge pgsql_tmp?
|
|
|
|
|
|
|
|
Dannyj katalog soderzhit vremennye fajly, generiruemye obrabotchikom
|
|
|
|
zaprosa. Naprimer, esli dlya vypolneniya ORDER BY nuzhna sortirovka i
|
|
|
|
`eta sortirovka trebuet pamyati bol'she, chem dopuskaet parametr -S u
|
|
|
|
backend'a, to dlya hraneniya dopolnitel'nyh dannyh sozdayutsya
|
|
|
|
vremennye fajly.
|
|
|
|
|
|
|
|
`Eti vremennye fajly dolzhny udalyat'sya avtomaticheski, no `etogo
|
|
|
|
mozhet ne proizojti, esli backend ruhnul vo vremya sortirovki. Ostanov
|
|
|
|
i zapusk servernogo processa obespechit ih udalenie iz kataloga.
|
2002-08-23 10:53:20 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
3.10) Pochemu neobhodimo delat' dump i restore pri obnovlenii vypuskov
|
|
|
|
PostgreSQL?
|
|
|
|
|
|
|
|
Razrabotchiki PostgreSQL delayut tol'ko nebol'shie izmeneniya mezhdu
|
|
|
|
podvypuskami. Takim obrazom obnovlenie s versii 7.2 do 7.2.1 ne
|
|
|
|
trebuet vypolneniya dump i restore. Odnako pri vyhode ocherednogo
|
|
|
|
vypuska (t.e. pri obnovlenii naprimer, s 7.2 na 7.3) chasto menyaetsya
|
|
|
|
vnutrennij format sistemnyh tablic i fajlov dannyh. `Eti izmeneniya
|
|
|
|
chasto nosyat kompleksnyj harakter, tak chto net vozmozhnosti
|
|
|
|
obespechit' obratnuyu sovmestimost' fajlov dannyh. Vypolenie dump
|
|
|
|
pozvolyaet poluchit' dannye v obschem formate, kotoryj zatem mozhet
|
|
|
|
byt' zagruzhen pri ispol'zovanii novogo vnutrennego formata.
|
|
|
|
|
|
|
|
V teh vypuskah, gde format dannyh na diske ne menyaetsya, dlya
|
|
|
|
provedeniya obnovleniya mozhet byt' ispol'zovan scenarij pg_upgrade
|
|
|
|
bez ispol'zovaniya dump/restore. Kommentarii k vypusku govorit kogda
|
|
|
|
mozhno ispol'zovat' pg_upgrade dlya `etogo vypuska.
|
2002-04-12 17:17:10 +08:00
|
|
|
_________________________________________________________________
|
|
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
Voprosy `ekspluatacii
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
4.1) V chem otlichie mezhdu binarnym i normal'nym kursorom?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Smotrite opisanie na stranicah rukovodstva posvyaschennym DECLARE.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.2) Kak vypolnit' SELECT tol'ko dlya neskol'kih pervyh strochek zaprosa?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Smotrite stanicu rukovodstva posvyaschennuyu FETCH ili ispol'zujte
|
|
|
|
SELECT ... LIMIT....
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
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Dazhe esli vy hotite poluchit' tol'ko pervye neskol'ko zapisej, budet
|
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|
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vypolnen ves' zapros. Rassmotrim zapros, kotoryj imeet ORDER BY. Esli
|
|
|
|
est' kakoj-libo indeks, kotoryj sovpadaet s ORDER BY, PostgreSQL
|
|
|
|
mozhet vydat' tol'ko neskol'ko pervyh zaproshennyh zapisej ili mozhet
|
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vypolnyat' zapros poka ne budut vydany zhelaemye zapisi.
|
2002-04-12 17:17:10 +08:00
|
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
4.3) Kak poluchit' spisok tablic ili drugih komponentov v psql?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Vy mozhete posmotret' ishodnyj kod psql v fajle
|
|
|
|
pgsql/src/bin/psql/describe.c. On soderzhit komandy SQL kotorye
|
|
|
|
generiruyutsya pri vvode v psql komand, nachinayuschihsya s obratnoj
|
|
|
|
kosoj cherty. Vy takzhe moezhete zapustit' psql s opciej -E tak,
|
|
|
|
chtoby `eta programma vydavala zaprosy, kotorye ona ispol'zuet dlya
|
|
|
|
vypolneniya zadannyh vami komand.
|
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|
|
4.4) Kak udalit' kolonku iz tablicy?
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
`Eta funkcional'nost' byla dobavlena v vypusk 7.3 s operatorom ALTER
|
|
|
|
TABLE DROP COLUMN. V rannih versiyah, mozhno sdelat' tak:
|
2002-06-08 12:23:45 +08:00
|
|
|
BEGIN;
|
|
|
|
LOCK TABLE old_table;
|
2002-11-11 03:48:41 +08:00
|
|
|
SELECT ... -- vyborka vseh kolonok za isklyucheniem toj, kotoruyu hotite u
|
|
|
|
dalit'
|
2002-04-12 17:17:10 +08:00
|
|
|
INTO TABLE new_table
|
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|
|
FROM old_table;
|
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|
|
DROP TABLE old_table;
|
|
|
|
ALTER TABLE new_table RENAME TO old_table;
|
2002-06-08 12:23:45 +08:00
|
|
|
COMMIT;
|
2002-04-12 17:17:10 +08:00
|
|
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|
2002-11-11 03:48:41 +08:00
|
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|
4.5) Kakovy maksimal'nye razmery dlya zapisej, tablic i bazy dannyh?
|
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|
|
Suschestvuyut sleduyuschie ogranicheniya:
|
|
|
|
Maksimal'nyj razmer bazy? neogranichen (suschestvuyut bazy na
|
2003-04-01 11:10:44 +08:00
|
|
|
4 TB)
|
2002-11-11 03:48:41 +08:00
|
|
|
Maksimal'nyj razmer tablicy? 16 TB
|
|
|
|
Maksimal'nyj razmer zapisi? 1.6 TB
|
|
|
|
Maksimal'nyj razmer polya? 1 GB
|
|
|
|
Maksimal'noe kolichestvo zapisej v tablice? neogranicheno
|
|
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|
Maksimal'noe kolichestvo kolonok v tablice? 250-1600 v zavisimosti ot ti
|
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|
pa
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|
Maksimal'noe kolichestvo indeksov v tablice? neogranicheno
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
Razumeetsya, ponyatie "neogranicheno" na samom dele ogranichivaetsya
|
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|
|
dostupnym diskovym prostranistvom i razmerami pamyati/svoppinga. Kogda
|
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|
znacheniya perechislennye vyshe neopravdano bol'shie, mozhet
|
|
|
|
postradat' proizvoditel'nost'.
|
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|
|
|
|
|
|
Maksimal'nyj razmer tablicy v 16 TB ne trebuet chtoby operacionnaya
|
|
|
|
sistema podderzhivala fajly bol'shih razmerov. Bol'shie tablicy
|
|
|
|
hranyatsya kak mnozhestvo fajlov razmerom v 1 GB, tak chto
|
|
|
|
ogranicheniya, kotorye nakladyvaet fajlovaya sistema ne vazhny.
|
|
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|
Maksimal'nyj razmer tablicy i maksimal'noe kolichestvo kolonok mogut
|
|
|
|
byt' uvelicheny, esli razmer bloka po umolchaniyu budet uvelichen do
|
|
|
|
32k.
|
|
|
|
|
|
|
|
4.6) Kak mnogo diskovogo prostranstva v baze dannyh nuzhno dlya sohraneniya
|
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|
|
dannyh iz obychnogo tekstovogo fajla?
|
|
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|
|
|
|
|
SUBD PostgreSQL mozhet potrebovat'sya diskovogo prostranstva do 5 raz
|
|
|
|
bol'she dlya sohraneniya dannyh iz prostogo tekstovogo fajla.
|
|
|
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|
V kachestve primera, rassmotrim fajl v 100,000 strok v kazhdoj, iz
|
|
|
|
kotoryh celoe chislo i tekstovoe opisanie. Pri `etom dlina teksta, v
|
|
|
|
srednem, sostavlyaet 20 bajt. Razmer prostogo fajla sostavit 2.8 MB.
|
|
|
|
Razmer bazy PostgreSQL, soderzhaschej `eti zhe dannye sostavit
|
|
|
|
priblizitel'no 6.4 MB iz kotoryh:
|
|
|
|
36 bajt: na kazhdyj zagolovok zapisi (priblizitel'no)
|
|
|
|
+ 24 bajta: odno pole s celochislennym tipom i odno tekstovoe pole
|
|
|
|
+ 4 bajta: ukazatel' na stranice dlya vsej zapisi
|
2002-04-12 17:17:10 +08:00
|
|
|
----------------------------------------
|
2002-11-11 03:48:41 +08:00
|
|
|
64 bajt na zapis'
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Razmer stranicy dannyh v PostgreSQL sostavlyaet 8192 bajt (8 KB), tak chto:
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
8192 bajt na stranicu
|
|
|
|
------------------- = 128 zapisej na stranicu BD (s okrugleniem)
|
|
|
|
64 bajt na zapis'
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
100000 strok dannyh
|
|
|
|
-------------------- = 782 stranicy v BD
|
|
|
|
128 zapisej na stranicu
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
782 stranicy BD * 8192 bajt na stranicu = 6,406,144 bajt (6.4 MB)
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Indeksy ne trebuyut tak mnogo, no poskol'ku oni sozdayutsya dlya
|
|
|
|
bol'shogo kolichestva dannyh, oni takzhe mogut byt' veliki.
|
|
|
|
|
|
|
|
Znacheniya NULL sohranyayutsya v bitah i po`etomu oni zanimayut ochen'
|
|
|
|
malo mesta.
|
|
|
|
|
|
|
|
4.7) Kak mne ubedit'sya, chto suschestvuyut nuzhnye mne tablicy, indeksy,
|
|
|
|
bazy dannyh i pol'zovateli?
|
|
|
|
|
|
|
|
psql imeet neskol'ko komand, nachinayuschihsya s obratnoj kosoj
|
|
|
|
cherty, dlya togo chtoby prosmatrivat' takuyu informaciyu. Ispol'zujte
|
|
|
|
\? dlya togo, chtoby uvidet' `eti komandy. Takzhe suschestvuyut
|
|
|
|
sistemnye tablicy, imya kotoryh nachinaetsya na pg_ i v kotoryh takzhe
|
|
|
|
soderzhitsya `eta informaciya. Eschio, psql -l pokazhet spisok vseh
|
|
|
|
baz dannyh.
|
|
|
|
|
|
|
|
Takzhe smotrite fajl pgsql/src/tutorial/syscat.source. V nem
|
|
|
|
predstavleny mnogie operatory SELECT kotorye nuzhny dlya polucheniya
|
|
|
|
informacii iz sistemnyh tablic bazy dannyh.
|
|
|
|
|
|
|
|
4.8) U menya medlenno rabotayut zaprosy ili ne proishodit ispol'zovaniya
|
|
|
|
indeksov. Pochemu?
|
|
|
|
|
|
|
|
Indeksy ne ispol'zuyutsya dlya kazhdogo zaprosa avtomaticheski. Oni
|
|
|
|
ispol'zuyutsya tol'ko esli tablica bol'she minimal'nogo razmera i
|
|
|
|
zapros vybiraet tol'ko malen'kij procent zapisej v tablice. Tak
|
|
|
|
ustroeno, potomu chto dostup k disku s primeneniem randomizacii pri
|
|
|
|
skanirovanii indeksov mozhet byt' medlennee, chem prostoe chtenie
|
|
|
|
tablicy ili ee posledovatel'noe skanirovanie.
|
|
|
|
|
|
|
|
CHtoby opredelit' neobhodimost' ispol'zovaniya indeksa dlya kakoj-libo
|
|
|
|
tablicy, PostgreSQL dolzhen imet' statistiku po `etoj tablice. `Eta
|
|
|
|
statistika sobiraetsya pri ispol'zovanii VACUUM ANALYZE ili prosto
|
|
|
|
ANALYZE. Ispol'zuya statistiku, optimizator uznaet o tom kak mnogo
|
|
|
|
zapisej v tablice i esli on dolzhen ispol'zovat' indeksy, to on mozhet
|
|
|
|
prinimat' luchshie resheniya. Statistika takzhe vliyaet na opredelenie
|
|
|
|
optimal'nogo poryadka svyazyvaniya i metoda svyazyvaniya. Sbor
|
|
|
|
statistiki dolzhen periodicheski vypolnyatsya pri izmenenii
|
|
|
|
soderzhimogo tablicy.
|
|
|
|
|
|
|
|
Obychno indeksy ne ispol'zuyutsya dlya ORDER BY ili dlya vypolneniya
|
|
|
|
svyazyvanij. Posledovatel'nyj perebor sleduyuschij za yavnoj
|
|
|
|
sortirovkoj obychno bystree, chem poisk po indeksam v bol'shoj
|
|
|
|
tablice. Odnako, ORDER BY chasto kombiniruetsya s LIMIT i v `etom
|
|
|
|
sluchae indeks budet ispol'zovat'sya, poskol'ku pri vypolnenii budet
|
|
|
|
vozvraschat'sya nebol'shaya chast' tablicy. Fakticheski MAX() i MIN()
|
|
|
|
ne ispol'zuyut indeksy, no indeks ispol'zuetsya pri postroenii
|
|
|
|
zaprosov s ORDER BY i LIMIT:
|
2002-08-23 10:53:20 +08:00
|
|
|
SELECT col
|
|
|
|
FROM tab
|
|
|
|
ORDER BY col [ DESC ]
|
2002-11-11 03:48:41 +08:00
|
|
|
LIMIT 1;
|
2002-08-23 10:53:20 +08:00
|
|
|
|
2003-02-14 22:05:00 +08:00
|
|
|
Esli vam kazhetsya, chto optimizator nekorretno vybiraet
|
|
|
|
posledovatel'nyj perebor, ispol'zujte SET enable_seqscan TO 'off' i
|
|
|
|
zapustite testy, chtoby uvidet', ne stalo-li skanirovanie indeksov
|
|
|
|
bystree.
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Kogda ispol'zuyutsya operacii s shablonami, naprimer LIKE ili ~,
|
|
|
|
indeksy mogut byt' ispol'zovany v sleduyuschih sluchayah:
|
|
|
|
* Nachalo stroki poiska dolzhno sovpadat' s nachalom iskomoj stroki,
|
|
|
|
t.e.:
|
|
|
|
+ LIKE shablony ne dolzhny nachinat'sya s %..
|
|
|
|
+ ~ shablony regulyarnyh vyrazhenij dolzhna nachinat'sya na ^.
|
|
|
|
* Stroka poiska ne dolzhna nachinat'sya s simvola klassa, t.e.
|
|
|
|
[a-e].
|
|
|
|
* Poisk nezavisimyj ot registra, takoj kak ILIKE i ~* ne ispol'zuet
|
|
|
|
indeksy. Vmesto nego, ispol'zujte funkcional'nye indeksy, kotorye
|
|
|
|
opisyvayutsya v sekcii 4.12.
|
|
|
|
* Vo vremya initdb dolzhna ispol'zovat'sya lokal' po umolchaniyu C.
|
2002-08-23 10:53:20 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.9) Kak posmotret' na to, kak optimizator vypolnyaet moj zapros?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Smotrite stranicu rukovodstva posvyaschennuyu EXPLAIN.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.10) CHto takoe R-tree indeks?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
R-tree indeks ispol'zuetsya dlya indeksirovaniya prostranstvennyh
|
|
|
|
dannyh. Indeks h`esha ne mozhet upravlyat' poiskami diapazona. B-tree
|
|
|
|
indeks upravlyaet tol'ko poiskami diapazona v odnom izmerenii. R-tree
|
|
|
|
indeks mozhet upravlyat' mnogorazmernymi dannymi. Naprimer, esli
|
|
|
|
R-tree indeks mozhet byt' vstroen v atribut tipa point, to sistema
|
|
|
|
mozhet bolee `effektivno otvetit' na zapros tipa "vybrat' vse tochki
|
|
|
|
vnutri zadannogo chetyrehugol'nika."
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Kanonicheskij istochnik, opisyvayuschij pervonachal'noe sozdanie
|
|
|
|
R-tree `eto:
|
2002-04-12 17:17:10 +08:00
|
|
|
|
|
|
|
Guttman, A. "R-trees: A Dynamic Index Structure for Spatial
|
|
|
|
Searching." Proceedings of the 1984 ACM SIGMOD Int'l Conf on Mgmt of
|
|
|
|
Data, 45-57.
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Vy mozhete najti `etot dokument v knige Stonebraker'a "Readings in
|
2002-04-12 17:17:10 +08:00
|
|
|
Database Systems".
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Vstroennnye R-tree mogut upravlyat' poligonami i boksami. V teorii,
|
|
|
|
R-tree mogut byt' rasshireny dlya upravleniya bol'shim kolichestvom
|
|
|
|
izmerenij. Na praktike, rasshirenie R-tree trebuet nekotoryh usilij i
|
|
|
|
u nas, v dannyj moment, net kakoj-libo dokumentacii o tom, kak `eto
|
|
|
|
sdelat'.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.11) CHto takoe Genetic Query Optimizer?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Modul' GEQO proizvodit bystruyu optimizaciyu zaprosa, kogda proishodit
|
|
|
|
svyazyvanie mnogih tablic cherez Genetic Algorithm (GA). `Eto
|
|
|
|
pozvolyaet upravlyat' bol'shimi zaprosami na svyazyvanie cherez
|
|
|
|
neistoschayuschij poisk.
|
|
|
|
|
|
|
|
4.12) Kak mne vypolnit' poisk regulyarnogo vyrazheniya i poisk nezavisimyj
|
|
|
|
ot registra bukv poisk regulyarnogo vyrazheniya? Kak mne ispol'zovat'
|
|
|
|
indeks dlya poiska nezavisimogo ot registra bukv?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Operator ~ proizvodit poisk regulyarnogo vyrazheniya, a operator ~*
|
|
|
|
proizvodit nezavisimyj ot registra bukv poisk regulyarnogo
|
|
|
|
vyrazheniya. Nezavisimyj ot registra variant LIKE nazyvaetsya ILIKE.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Nezavisimoe ot registra sravnenie obychno vyrazhaetsya tak:
|
2002-04-12 17:17:10 +08:00
|
|
|
SELECT *
|
|
|
|
FROM tab
|
2002-11-11 03:48:41 +08:00
|
|
|
WHERE lower(col) = 'abc';
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
`Eta konstrukciya ne budet ispol'zovat' standartnyj indeks. Odnako,
|
|
|
|
esli vy sozdadite funkcional'nyj indeks, on budet ispol'zovan:
|
|
|
|
CREATE INDEX tabindex ON tab (lower(col));
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.13) Kak ya mogu opredelit', chto znachenie polya ravno NULL v kakom-libo
|
|
|
|
zaprose?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Vy prosto sravnivaete znachenie s IS NULL i IS NOT NULL.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
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4.14) Kakovy otlichiya mezhdu raznymi simvol'nymi tipami?
|
2002-04-12 17:17:10 +08:00
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|
2002-11-11 03:48:41 +08:00
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Tip Vnutrennee imya Zamechaniya
|
2002-04-12 17:17:10 +08:00
|
|
|
--------------------------------------------------
|
2002-11-11 03:48:41 +08:00
|
|
|
VARCHAR(n) varchar razmer zadaet maksimal'nuyu dlinu, net zapolnen
|
|
|
|
iya
|
2003-02-14 22:05:00 +08:00
|
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|
CHAR(n) bpchar zapolnyaetsya pustotoj do fiksirovannoj dliny
|
2002-11-11 03:48:41 +08:00
|
|
|
TEXT text net zadavaemogo verhnego ogranicheniya ili dlin
|
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|
y
|
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|
|
BYTEA bytea massiv bajt peremennoj dliny (mozhno ispol'zova
|
|
|
|
t' null-bajt bez opaski)
|
2003-03-07 13:46:51 +08:00
|
|
|
"char" char odin simvol
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
Vnutrennee imya vy mozhete uvidet', kogda smotrite sistemnye katalogi
|
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|
i v nekotoryh soobscheniyah ob oshibkah.
|
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|
2003-03-07 13:46:51 +08:00
|
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|
Pervye chetyre tipa yavlyayutsya "varlena" tipami (t.e., pervye
|
2002-11-11 03:48:41 +08:00
|
|
|
chetyre bajta na diske yavlyayutsya dlinnoj, za kotoroj sleduyut
|
|
|
|
dannye). Takim obrazom, fakticheski ispol'zuemoe prostranstvo bol'she,
|
|
|
|
chem oboznachennyj razmer. Odnako, `eti tipy dannyh takzhe poddayutsya
|
|
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|
szhatiyu ili mogut byt' sohraneny ne v strokom vide cherez TOAST, tak
|
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|
chto zanimaemoe diskovoe prostranstvo mozhet takzhe byt' i men'she,
|
|
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|
chem ozhidalos'.
|
2003-02-14 22:05:00 +08:00
|
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|
VARCHAR(n) - `eto luchshee reshenie, kogda nuzhno hranit' stroki
|
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|
peremennoj dliny, ne prevyshayuschie opredelennogo razmera. TEXT -
|
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|
`eto luchshee reshenie dlya strok neogranichennoj dliny, s maksimal'no
|
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|
dopustimoj dlinoj v 1 gigabajt.
|
2002-11-11 03:48:41 +08:00
|
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|
CHAR(n) - `eto luchshee reshenie dlya hraneniya strok, kotorye obychno
|
2003-02-14 22:05:00 +08:00
|
|
|
imeyut odinakovuyu dlinu. CHAR(n) zapolnyaetsya pustotoj do zadannoj
|
|
|
|
dliny, v to vremya kak VARCHAR(n) hranit tol'ko simvoly, iz kotoryh
|
|
|
|
sostoit stroka. BYTEA ispol'zuetsya dlya hraneniya binarnyh dannyh,
|
2003-03-07 13:46:51 +08:00
|
|
|
znacheniya kotoryh mogut vklyuchat' NULL bajty. Vse tipy opisannye
|
|
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|
zdes', imeyut shodnye harakteristiki proizvoditel'nosti.
|
2002-11-11 03:48:41 +08:00
|
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|
4.15.1) Kak mne sozdat' pole serial/s-avto-uvelicheniem?
|
|
|
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|
|
PostgreSQL podderzhivaet tip dannyh SERIAL. On avtomaticheski sozdaet
|
|
|
|
posledovatel'nost' i indeks dlya kolonki. Naprimer:
|
2002-04-12 17:17:10 +08:00
|
|
|
CREATE TABLE person (
|
|
|
|
id SERIAL,
|
|
|
|
name TEXT
|
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|
|
);
|
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|
2002-11-11 03:48:41 +08:00
|
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|
avtomaticheski transliruetsya v:
|
2002-04-12 17:17:10 +08:00
|
|
|
CREATE SEQUENCE person_id_seq;
|
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|
|
CREATE TABLE person (
|
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|
|
id INT4 NOT NULL DEFAULT nextval('person_id_seq'),
|
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|
|
name TEXT
|
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|
|
);
|
|
|
|
CREATE UNIQUE INDEX person_id_key ON person ( id );
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
Smotrite podrobnosti o posledovatel'nostyah na stranice rukovodstva
|
|
|
|
posvyaschennoj create_sequence. Vy takzhe mozhete ispol'zovat' kazhdoe
|
|
|
|
pole OID v zapisi kak unikal'noe znachenie. Odnako, esli vam nuzhen
|
|
|
|
damp i perezagruzka bazy dannyh, vam neobhodimo ispol'zovat' komandu
|
|
|
|
pg_dump s opciej -o ili opciyu COPY WITH OIDS dlya sohraneniya
|
|
|
|
znachenij polya OID.
|
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|
4.15.2) Kak mne poluchit' znachenie pri vstavke SERIAL?
|
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|
Odin iz sposobov sostoit v poluchenii sleduyuschego znacheniya SERIAL
|
|
|
|
iz ob"ekta sequence s pomosch'yu funkcii nextval() pered vstavkoj i
|
|
|
|
zatem vstavlyat' `eto znachenie yavno. Ispol'zujte tablicu-primer v
|
|
|
|
4.15.1, primer v psevdoyazyke pokazhet kak `eto delaetsya:
|
|
|
|
new_id = execute("SELECT nextval('person_id_seq')");
|
|
|
|
execute("INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal')");
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
|
|
Zatem vy dolzhny takzhe sohranit' novoe znachenie v peremennoj new_id
|
|
|
|
dlya ego ispol'zovaniya v drugih zaprosah (naprimer takih kak vneshnij
|
|
|
|
klyuch dlya tablicy person). Zametim, chto imya avtomaticheski
|
|
|
|
sozdannogo ob"ekta SEQUENCE budet <table>_<serialcolumn>_seq, gde
|
|
|
|
table i serialcolumn yavlyayutsya sootvetstvenno imenami vashej
|
|
|
|
tablicy i vashej kolonki SERIAL.
|
|
|
|
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|
|
|
V kachestve al'ternativy, vy mozhete poluchit' naznachennoe znachenie
|
|
|
|
SERIAL s pomosch'yu funkcii currval() posle provedeniya obychnoj
|
|
|
|
operacii vstavki, naprimer
|
|
|
|
execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
|
|
|
|
new_id = execute("SELECT currval('person_id_seq')");
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
I nakonec, vy mozhete ispol'zovat' znachenie OID, vozraschaemoe iz
|
|
|
|
opertora INSERT chtoby uvidet' znachenie po umolchaniyu, chto
|
|
|
|
predpolozhitel'no yavlyaetsya naimenee perenosimym na drugie platformy
|
|
|
|
resheniem. V Perl, ispol'zuya DBI s modulei Edmund Mergl'ya DBD::Pg,
|
|
|
|
znachenie oid stanovitsya dostupnym cherez $sth->{pg_oid_status} posle
|
2002-04-12 17:17:10 +08:00
|
|
|
$sth->execute().
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.15.3) Ne mozhet li poluchit'sya tak, chto ispol'zovanie currval() i
|
|
|
|
nextval() privedet k zaciklirovaniyu s drugimi pol'zovatelyami?
|
|
|
|
|
|
|
|
Net. currval() vozvraschaet tekuschee znachenie, naznachennoe vashem
|
|
|
|
backend'om, a ne drugimi pol'zovatelyami.
|
|
|
|
|
|
|
|
4.15.4) Pochemu chisla iz moej posledovatel'nosti ne ispol'zuyutsya snova
|
|
|
|
pri otmene tranzakcii? Pochemu sozdayutsya razryvy pri numeracii v kolonke,
|
|
|
|
gde ya ispol'zuyu posledovatel'nost'/SERIAL?
|
|
|
|
|
|
|
|
Dlya realizacii konkuretnosti, znacheniya posledovatel'nostej, pri
|
|
|
|
neobhodimosti vydayutsya vo vremya zapuska tranzakcij i ne
|
|
|
|
blokiruyutsya do polnogo vypolneniya tranzakcij. `Eto mozhet vyzyvat'
|
|
|
|
razryvy v numeracii pri otmene tranzakcij.
|
|
|
|
|
|
|
|
4.16) CHto takoe OID? CHto takoe TID?
|
|
|
|
|
|
|
|
Polya OID sluzhat unikal'nymi idetifikatorami zapisej v PostgreSQL.
|
|
|
|
Kazhdaya zapis', kotoraya sozdaiotsya v PostgreSQL poluchaet
|
|
|
|
unikal'nyj OID. Vse znacheniya OID generiruemye vo vremya initdb
|
|
|
|
imeyut znacheniya men'she 16384 (iz include/access/transam.h). Vse
|
|
|
|
sozdannye pol'zovatelem OID imeyut bOl'shie znachenie. Po umolchaniyu,
|
|
|
|
vse `eti OID yavlyayutsya unikal'nymi ne tol'ko vnutri kakoj-libo
|
|
|
|
tablicy ili bazy dannyh, no i vnutri vsej SUBD PostgreSQL.
|
|
|
|
|
|
|
|
PostgreSQL ispol'zuet OID v svoih vnutrennih sistemnyh tablicah dlya
|
|
|
|
svyazi zapisej i tablic. Znacheniya OID mogut byt' ispol'zovany dlya
|
|
|
|
identifikacii zadannyh pol'zovatelem zapisej, a takzhe ispol'zovat'sya
|
|
|
|
pri svyazyvaniyah. Rekomenduetsya ispol'zovat' tip kolonki OID dlya
|
|
|
|
hraneniya znachenij OID Vy mozhete sozdat' indeks na pole OID dlya
|
|
|
|
bolee bystrogo dostupa.
|
|
|
|
|
|
|
|
Znacheniya OID naznachayutsya dlya vseh novyh zapisej iz central'noj
|
|
|
|
oblasti, kotorye ispol'zuyutsya vsemi vsemi bazami dannyh. Esli vy
|
|
|
|
hotite izmenit' OID na kakoe-libo drugoe znachenie ili esli vy hotite
|
|
|
|
sozdat' kopiyu tablicy s takimizhe OID, to `eto mozhno sdelat' tak:
|
2002-04-12 17:17:10 +08:00
|
|
|
CREATE TABLE new_table(old_oid oid, mycol int);
|
|
|
|
SELECT old_oid, mycol INTO new FROM old;
|
|
|
|
COPY new TO '/tmp/pgtable';
|
|
|
|
DELETE FROM new;
|
|
|
|
COPY new WITH OIDS FROM '/tmp/pgtable';
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
OID hranitsya kak 4-h bajtnoe celoe i ne mozhet prevyshat' znachenie v
|
|
|
|
4 milliarda. Odnako, esche nikto ne soobschil o tom, chto takoe
|
|
|
|
proizoshlo, no my planiruem do togo kak `eto sluchit'sya izbavitsya ot
|
|
|
|
`etogo ogranicheniya.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
TID ispol'zuetsya dlya identifikacii special'nyh fizicheskih zapisej s
|
|
|
|
blochnymi i offset znacheniyami. TID izmenyaetsya posle togo kak
|
|
|
|
zapisi byli izmeneny ili peregruzheny.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
TID ispol'zuetsya indeksnymi zapisyami v kachestve ukazatelya na
|
|
|
|
fizicheskie zapisi.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.17) CHto oznachayut nekotorye terminy ispol'zuemye v PostgreSQL?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Nekotoryj ishodnyj kod i staraya dokumentaciya ispol'zuyut
|
|
|
|
obscheupotrebitel'nye terminy. Vot nekotorye iz nih:
|
2002-04-12 17:17:10 +08:00
|
|
|
* table, relation, class
|
|
|
|
* row, record, tuple
|
|
|
|
* column, field, attribute
|
|
|
|
* retrieve, select
|
|
|
|
* replace, update
|
|
|
|
* append, insert
|
|
|
|
* OID, serial value
|
|
|
|
* portal, cursor
|
|
|
|
* range variable, table name, table alias
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Spisok obschih terminov po bazam dannyh mozhno najti na
|
|
|
|
http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary
|
|
|
|
/glossary.html
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.18) Pochemu ya poluchayu oshibku "ERROR: Memory exhausted in
|
|
|
|
AllocSetAlloc()"?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Predpolozhitel'no u vas zakonchilas' virtual'naya pamyat' ili chto
|
|
|
|
vashe yadro imeet malen'kij limit na opredelennye resursy. Popytajtes'
|
|
|
|
pered zapuskom postmaster vypolnit' sleduyuschie komandy:
|
2002-04-12 17:17:10 +08:00
|
|
|
ulimit -d 262144
|
|
|
|
limit datasize 256m
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
V zavisimosti ot komandnogo interpretatora shell, tol'ko odna iz
|
|
|
|
dannyh komand vypolnitsya uspeshno, no ona pozvolit vam ustanovit'
|
|
|
|
bol'shij segment dannyh processa i vozmozhno reshit problemu. `Eta
|
|
|
|
komanda izmenyaet parametry tekuschego processa i vseh ego potomkov,
|
|
|
|
sozdannyh posle eio zapuska. Esli u vas voznikla problema s SQL
|
|
|
|
klientom, potomu chto backend vozvraschaet slishkom bol'shoj ob"em
|
|
|
|
dannyh, popytajtes' vypolnit' `etu komandu pered zapuskom klienta.
|
|
|
|
|
|
|
|
4.19) Kak mne uznat', kakaya versiya PostgreSQL zapuschena?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Iz psql, naberite SELECT version();
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.20) Pochemu pri rabote s moim bol'shim ob"ektom ya poluchayu oshibku
|
|
|
|
"invalid large obj descriptor"?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Vam nuzhno pri ispol'zovanii bol'shogo ob"ekta pomestit' v nachale
|
|
|
|
BEGIN WORK i v konce COMMIT, a vnutri poluchivshegosya bloka lo_open
|
|
|
|
... lo_close.
|
|
|
|
|
|
|
|
V nastoyaschij moment PostgreSQL trebuet, chtoby pri zakrytii
|
|
|
|
bol'shogo ob"ekta proishodilo vypolnenie tranzakcii. Takim obrazom,
|
|
|
|
pervaya zhe popytka sdelat' chto-libo s bol'shim ob"ektom, ne
|
|
|
|
soblyudaya dannogo pravila privedet k soobscheniyu invalid large obj
|
|
|
|
descriptor, tak kak kod vypolnyayuschij rabotu nad bol'shim ob"ektom
|
|
|
|
(po krajnej mere v nastoyaschij moment) budet generirovat' soobschenie
|
|
|
|
ob oshibke esli vy ne ispol'zuete tranzakciyu.
|
|
|
|
|
|
|
|
Esli vy ispol'zuete takoj interfejs klienta kak ODBC, vam vozmozhno
|
|
|
|
ponadobitsya ustanovit' auto-commit off.
|
|
|
|
|
|
|
|
4.21) Kak mne sozdat' kolonku kotoraya po umolchaniyu budet soderzhat'
|
|
|
|
tekuschee vremya?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
Ispol'zujte CURRENT_TIMESTAMP:
|
2002-04-12 17:17:10 +08:00
|
|
|
CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.22) Pochemu moi podzaprosy, ispol'zuyuschie IN tak medlenno rabotaeyut?
|
|
|
|
|
|
|
|
V nastoyaschij moment, my svyazyvaem pozaprosy dlya vneshnih zaprosov
|
|
|
|
cherez posledovatel'nyj perebor rezul'tata podzaprosa dlya kazhdoj
|
|
|
|
zapisi vneshnego zaprosa. Esli podzapros vozvraschaet tol'ko neskol'ko
|
|
|
|
zapisej i vneshnij zapros vozvraschaet mnogo zapisej, IN rabotaet
|
|
|
|
naibolee bystro. CHtoby uvelichit' skorost' v drugih zaprosah,
|
|
|
|
zamenite IN na EXISTS:
|
|
|
|
SELECT *
|
2002-04-12 17:17:10 +08:00
|
|
|
FROM tab
|
2002-11-11 03:48:41 +08:00
|
|
|
WHERE col IN (SELECT subcol FROM subtab);
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
na:
|
|
|
|
SELECT *
|
2002-04-12 17:17:10 +08:00
|
|
|
FROM tab
|
2002-11-11 03:48:41 +08:00
|
|
|
WHERE EXISTS (SELECT subcol FROM subtab WHERE subcol = col);
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
CHtoby takaya konstrukciya rabotala bystro, kolonka subcol dolzhna
|
2003-02-14 22:05:00 +08:00
|
|
|
byt' proindeksirovana. `Eta problema proizvoditel'nosti budet
|
|
|
|
ustranena v versii 7.4.
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
4.23) Kak mne vypolnit' vneshnee svyazyvanie?
|
2002-04-12 17:17:10 +08:00
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
PostgreSQL podderzhivaet vneshnee svyazyvanie, ispol'zuya standartnyj
|
|
|
|
sintaksis SQL. Vot dva primera:
|
2002-04-12 17:17:10 +08:00
|
|
|
SELECT *
|
|
|
|
FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col);
|
|
|
|
|
2002-11-11 03:48:41 +08:00
|
|
|
ili
|
2002-04-12 17:17:10 +08:00
|
|
|
SELECT *
|
|
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FROM t1 LEFT OUTER JOIN t2 USING (col);
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2002-11-11 03:48:41 +08:00
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`Eto identichnye zaprosy svyazyvaniya t1.col i t2.col, takzhe
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vozvraschayut lyubye nesvyazannye zapisi v t1 (kotorye ne sovpadayut s
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t2). RIGHT svyazyvanie dolzhno dobavit' nesvyazannye zapisi t2. FULL
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svyazyvanie dolzhno vozvratit' sovpavshie zapisi plyus vse
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nesvyazannye zapisi iz t1 i t2. Slovo OUTER yavlyaetsya
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neobyazatel'nym i naznachaetsya v LEFT, RIGHT i FULL svyazyvaniyah.
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Obychnye svyazyvaniya nazyvayutsya INNER svyazyvaniya.
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V predyduschih versiyah, vneshnie svyazyvaniya mogli byt' `emulirovany
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ispol'zuya UNION i NOT IN. Naprimer, kogda proishodit svyazyvanie tab1
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i tab2, sleduyuschij zapros vypolnyaet vneshnee svyazyvanie dvuh
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tablic:
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2002-04-12 17:17:10 +08:00
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SELECT tab1.col1, tab2.col2
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FROM tab1, tab2
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WHERE tab1.col1 = tab2.col1
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UNION ALL
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SELECT tab1.col1, NULL
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FROM tab1
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WHERE tab1.col1 NOT IN (SELECT tab2.col1 FROM tab2)
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ORDER BY col1
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2002-11-11 03:48:41 +08:00
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4.24) Kak vypolnyat' zaprosy, ispol'zuyuschie neskol'ko baz dannyh?
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Ne suschestvuet sposoba sozdat' zapros k bazam dannyh otlichnym ot
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tekuschej. Poskol'ku PostgreSQL zagruzhaet sistemnye katalogi
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specifichnye dlya bazy dannyh, neponyatno dazhe, kak dolzhen sebya
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vesti takoj mezhbazovyj zapros.
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contrib/dblink pozvolyaet zaprosy mezhdu bazami, ispol'zuya vyzovy
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funkcij. Razumeetsya, klient mozhet odnovremenno ustanavlivat'
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soedieneniya s razlichnymi bazami dannyh i takih obrazom ob"edinyat'
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informaciyu iz nih.
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4.25) Kak mne vernut' iz funkcii neskol'ko zapisej?
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2003-06-03 00:39:06 +08:00
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V versii 7.3, vy mozhete legko vernut' neskol'ko zapisej ili kolonok
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iz kakoj-libo funkcii,
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http://techdocs.postgresql.org/guides/SetReturningFunctions
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.
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2002-11-11 03:48:41 +08:00
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4.26) Pochemu ya ne mogu nadezhno sozdavat'/udalyat' vremennye tablicy v
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funkciyah PL/PgSQL?
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PL/PgSQL k`eshiruet soderzhimoe funkcii i odin iz negativnyh `effektov
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`etogo sostoit v tom, chto esli funkciya PL/PgSQL obraschaetsya k
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vremennoj tablice i `eta tablica pozdnee udalyaetsya i peresozdaetsya,
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a funkciya zatem vyzyvaetsya snova, to ee vyzov privedet k oshibke,
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potomu chto sk`eshirovannoe soderzhimoe funkcii soderzhit ukazatel' na
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staruyu vremennuyu tablicu. CHtoby reshit' `etu problemu, ispol'zujte
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EXECUTE dlya dostupa k vremennym tablicam v PL/PgSQL. Ispol'zovanie
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`etogo operatora zastavit zapros peregenerirovat'sya kazhdyj raz.
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4.27) Kakie opcii replikacii suschestvuyut?
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Est' neskol'ko opcij dlya replikacii tipa master/slave. Oni dopuskayut
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ispol'zovanie tol'ko master servera dlya vneseniya izmenenij v bazu
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dannyh, a slave servery prosto pozvolyayut chitat' dannye iz bazy. Ob
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`etom chitajte zdes':
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http://gborg.PostgreSQL.org/genpage?replication_research. O replikacii
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s neskol'kimi master serverami chitajte zdes':
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http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php.
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4.28) Kakie opcii shifrovaniya suschestvuyut?
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* contrib/pgcrypto soderzhit mnogo funkcij shifrovaniya dlya
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ispol'zovaniya v SQL zaprosah.
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* Est' tol'ko odin sposob shifrovaniya dannyh, peredavaemyh ot
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klienta k serveru, cherez ispol'zovanie hostssl v pg_hba.conf.
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* Paroli pol'zovatelej k baze dannyh avtomaticheski shifruyutsya,
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pri sohranenii v versii 7.3. V predyduschih versiyah, vy dolzhny
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razreshit' opciyu PASSWORD_ENCRYPTION v postgresql.conf.
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* Server mozhno zapustit', ispol'zuya shifrovannuyu fajlovuyu
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sistemu.
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2002-04-12 17:17:10 +08:00
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_________________________________________________________________
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2002-11-11 03:48:41 +08:00
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Rasshireniya PostgreSQL
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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5.1) YA napisal funkciyu opredelyaemuyu pol'zovatelem. Kogda ya zapuskayu
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ee v psql, pochemu ya poluchayu dump core?
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
|
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Problema mozhet zaklyuchat'sya v neskol'kih veschah. Popytajtes'
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sperva protestirovat' vashu funkciyu v otdel'noj samostoyatel'noj
|
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programme.
|
2002-04-12 17:17:10 +08:00
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2002-11-11 03:48:41 +08:00
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5.2) Kak ya mogu vnesti nekotorye klassnye novye tipy i funkcii v
|
2002-04-12 17:17:10 +08:00
|
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PostgreSQL?
|
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|
2002-11-11 03:48:41 +08:00
|
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Otprav'te vashi rasshireniya v spisok rassylki pgsql-hackers i oni po
|
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|
vozmozhnosti budut pomescheny v podkatalog contrib/.
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
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5.3) Kak mne napisat' C funkciyu, vozvraschayuschuyu zapis'?
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
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|
V versiyah PostgreSQL, nachinaya s 7.3, funkcii, vozvraschayuschie
|
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|
|
tablicy polnost'yu podderzhivayutsya v C, PL/PgSQL i SQL. Podrobnosti
|
|
|
|
smotrite v Rukovodstve Programmista. Primer vozvraschayuschej tablicu
|
|
|
|
funkcii, napisannoj na C, mozhno najti v contrib/tablefunc.
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
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|
5.4) YA izmenil ishodnyj fajl. Pochemu posle perekompilyacii ya ne vizhu
|
|
|
|
izmenenij?
|
2002-04-12 17:17:10 +08:00
|
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|
2002-11-11 03:48:41 +08:00
|
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|
Fajly Makefile ne imeyut pravil'nyh zavisimostej dlya include fajlov.
|
|
|
|
Vy dolzhny vypolnit' make clean i zatem make. Esli vy ispol'zuete GCC
|
|
|
|
vy mozhete ispol'zovat' opciyu --enable-depend v configure chtoby
|
|
|
|
poruchit' kompilyatoru avtomaticheski otslezhivat' zavisimosti.
|