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Update FAQ.

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Bruce Momjian 2001-01-28 17:43:54 +00:00
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doc/src/FAQ/FAQ.html
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@ -53,8 +53,8 @@
</CENTER>
<A href="#2.1">2.1</A>) Are there <SMALL>ODBC</SMALL> drivers for
PostgreSQL?<BR>
<A href="#2.2">2.2</A>) What tools are available for use PostgreSQL
with Web pages?<BR>
<A href="#2.2">2.2</A>) What tools are available for use
PostgreSQL with Web pages?<BR>
<A href="#2.3">2.3</A>) Does PostgreSQL have a graphical user
interface? A report generator? An embedded query language
interface?<BR>
@ -103,16 +103,16 @@
database?<BR>
<A href="#4.7">4.7</A>) How much database disk space is required
to store data from a typical text file?<BR>
<A href="#4.8">4.8</A>) How do I find out what tables or
indexes are defined in the database?<BR>
<A href="#4.8">4.8</A>) How do I find out what tables or indexes
are defined in the database?<BR>
<A href="#4.9">4.9</A>) My queries are slow or don't make use of
the indexes. Why?<BR>
<A href="#4.10">4.10</A>) How do I see how the query optimizer is
evaluating my query?<BR>
<A href="#4.11">4.11</A>) What is an R-tree index?<BR>
<A href="#4.12">4.12</A>) What is the Genetic Query Optimizer?<BR>
<A href="#4.13">4.13</A>) How do I perform regular expression searches
and case-insensitive regular expression searches?<BR>
<A href="#4.13">4.13</A>) How do I perform regular expression
searches and case-insensitive regular expression searches?<BR>
<A href="#4.14">4.14</A>) In a query, how do I detect if a field
is <SMALL>NULL</SMALL>?<BR>
<A href="#4.15">4.15</A>) What is the difference between the
@ -198,8 +198,9 @@
<P>PostgreSQL Data Base Management System</P>
<P>Portions copyright (c) 1996-2001, PostgreSQL Global Development Group Portions
Copyright (c) 1994-6 Regents of the University of California</P>
<P>Portions copyright (c) 1996-2001, PostgreSQL Global Development
Group Portions Copyright (c) 1994-6 Regents of the University of
California</P>
<P>Permission to use, copy, modify, and distribute this software
and its documentation for any purpose, without fee, and without a
@ -499,8 +500,8 @@
"mailto:postgres95@openlink.co.uk">postgres95@openlink.co.uk</A>.</P>
<P>See also the <A href=
"http://www.PostgreSQL.org/users-lounge/docs/programmer/odbc.htm">ODBC chapter
of the Programmer's Guide</A>.</P>
"http://www.PostgreSQL.org/users-lounge/docs/programmer/odbc.htm">ODBC
chapter of the Programmer's Guide</A>.</P>
<H4><A name="2.2">2.2</A>) What tools are available for using
PostgreSQL with Web pages?</H4>
@ -839,16 +840,16 @@ Maximum number of columns in a table? 250-1600 depending on column types
Maximum number of indexes on a table? unlimited
</PRE>
Of course, these are not actually unlimited, but limited to
available disk space and memory/swap space. Performance may
suffer when these values get unusually large.
available disk space and memory/swap space. Performance may suffer
when these values get unusually large.
<P>The maximum table size of 16TB does not require large file
support from the operating system. Large tables are stored
as multiple 1GB files.
support from the operating system. Large tables are stored as
multiple 1GB files.</P>
<P>The maximum table size and maximum number of columns can be
increased by a factor of four if the default block size is
increased to 32k.
increased to 32k.</P>
<H4><A name="4.7">4.7</A>) How much database disk space is required
to store data from a typical text file?<BR>
@ -883,8 +884,8 @@ Maximum number of indexes on a table? unlimited
<P>Indexes do not require as much overhead, but do contain the data
that is being indexed, so they can be large also.</P>
<H4><A name="4.8">4.8</A>) How do I find out what tables or
indexes are defined in the database?</H4>
<H4><A name="4.8">4.8</A>) How do I find out what tables or indexes
are defined in the database?</H4>
<P><I>psql</I> has a variety of backslash commands to show such
information. Use \? to see them.</P>
@ -966,8 +967,8 @@ Maximum number of indexes on a table? unlimited
<P>The <I>~</I> operator does regular expression matching, and
<I>~*</I> does case-insensitive regular expression matching. The
case-insensitive variant of <SMALL>LIKE</SMALL>
is called <SMALL>ILIKE</SMALL>.</P>
case-insensitive variant of <SMALL>LIKE</SMALL> is called
<SMALL>ILIKE</SMALL>.</P>
<H4><A name="4.14">4.14</A>) In a query, how do I detect if a field
is <SMALL>NULL</SMALL>?</H4>
@ -1223,13 +1224,14 @@ BYTEA bytea variable-length byte array (null-safe)
SELECT *
FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col);
</PRE>
or
or
<PRE>
SELECT *
FROM t1 LEFT OUTER JOIN t2 USING (col);
</PRE>
These identical queries join t1.col to t2.col, and also return any
unjoined rows in t1 (those with no match in t2). A
<P>These identical queries join t1.col to t2.col, and also return
any unjoined rows in t1 (those with no match in t2). A
<SMALL>RIGHT</SMALL> join would add unjoined rows of t2. A
<SMALL>FULL</SMALL> join would return the matched rows plus all
unjoined rows from t1 and t2. The word <SMALL>OUTER</SMALL> is
@ -1242,7 +1244,7 @@ or
joining <I>tab1</I> and <I>tab2,</I> the following query does an
<I>outer</I> join of the two tables:<BR>
<BR>
</P>
<PRE>
SELECT tab1.col1, tab2.col2
FROM tab1, tab2
@ -1296,3 +1298,4 @@ or
compiler compute the dependencies automatically.</P>
</BODY>
</HTML>