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General function for SERIAL/IDENTITY/AUTOINCREMENT feature.

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Handle INSERT event in timetravel().
This commit is contained in:
Vadim B. Mikheev 1997-10-02 18:01:57 +00:00
parent cd7c56eeeb
commit d75206fdf5
8 changed files with 241 additions and 34 deletions
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3
contrib/spi/Makefile
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@ -9,7 +9,8 @@ ifdef REFINT_VERBOSE
CFLAGS+= -DREFINT_VERBOSE
endif
TARGETS= refint$(DLSUFFIX) refint.sql timetravel$(DLSUFFIX) timetravel.sql
TARGETS= refint$(DLSUFFIX) refint.sql timetravel$(DLSUFFIX) timetravel.sql \
autoinc$(DLSUFFIX) autoinc.sql
CLEANFILES+= $(TARGETS)

56
contrib/spi/README
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@ -8,8 +8,8 @@ table/field names (as described below) while creating a trigger.
check_primary_key () is to used for foreign keys of a table.
You are to create trigger (BEFORE INSERT OR UPDATE) using this
function on a table referencing another table. You are to specify
You have to create trigger (BEFORE INSERT OR UPDATE) using this
function on a table referencing another table. You have to specify
as function arguments: triggered table column names which correspond
to foreign key, referenced table name and column names in referenced
table which correspond to primary/unique key.
@ -18,8 +18,8 @@ one reference.
check_foreign_key () is to used for primary/unique keys of a table.
You are to create trigger (BEFORE DELETE OR UPDATE) using this
function on a table referenced by another table(s). You are to specify
You have to create trigger (BEFORE DELETE OR UPDATE) using this
function on a table referenced by another table(s). You have to specify
as function arguments: number of references for which function has to
performe checking, action if referencing key found ('cascade' - to delete
corresponding foreign key, 'restrict' - to abort transaction if foreign keys
@ -42,20 +42,26 @@ refint.source).
Old internally supported time-travel (TT) used insert/delete
transaction commit times. To get the same feature using triggers
you are to add to a table two columns of abstime type to store
you have to add to a table two columns of abstime type to store
date when a tuple was inserted (start_date) and changed/deleted
(stop_date):
CREATE TABLE XXX (
... ...
date_on abstime default currabstime(),
date_off abstime default 'infinity'
date_on abstime,
date_off abstime
... ...
);
- so, tuples being inserted with NULLs in date_on/date_off will get
_current_date_ in date_on (name of start_date column in XXX) and INFINITY in
date_off (name of stop_date column in XXX).
CREATE TRIGGER timetravel
BEFORE INSERT OR DELETE OR UPDATE ON tttest
FOR EACH ROW
EXECUTE PROCEDURE
timetravel (date_on, date_off);
Tuples being inserted with NULLs in date_on/date_off will get current
date in date_on (name of start_date column in XXX) and INFINITY in date_off
(name of stop_date column in XXX).
Tuples with stop_date equal INFINITY are "valid now": when trigger will
be fired for UPDATE/DELETE of a tuple with stop_date NOT equal INFINITY then
@ -72,7 +78,7 @@ DELETE: new tuple will be inserted with stop_date setted to current date
(and with the same data in other columns as in tuple being deleted).
NOTE:
1. To get tuples "valid now" you are to add _stop_date_ = 'infinity'
1. To get tuples "valid now" you have to add _stop_date_ = 'infinity'
to WHERE. Internally supported TT allowed to avoid this...
Fixed rewriting RULEs could help here...
As work arround you may use VIEWs...
@ -83,12 +89,9 @@ DELETE: new tuple will be inserted with stop_date setted to current date
timetravel() is general trigger function.
You are to create trigger BEFORE (!!!) UPDATE OR DELETE using this
function on a time-traveled table. You are to specify two arguments: name of
start_date column and name of stop_date column in triggered table.
currabstime() may be used in DEFAULT for start_date column to get
current date.
You have to create trigger BEFORE (!!!) INSERT OR UPDATE OR DELETE using
this function on a time-traveled table. You have to specify two arguments:
name of start_date column and name of stop_date column in triggered table.
set_timetravel() allows you turn time-travel ON/OFF for a table:
@ -96,9 +99,26 @@ set_timetravel() allows you turn time-travel ON/OFF for a table:
old status).
set_timetravel('XXX', 0) will turn TT OFF for table XXX (-"-).
Turning TT OFF allows you do with a table ALL what you want.
Turning TT OFF allows you do with a table ALL what you want!
There is example in timetravel.example.
To CREATE FUNCTIONs use timetravel.sql (will be made by gmake from
timetravel.source).
3. autoinc.c - function for implementing AUTOINCREMENT/IDENTITY feature.
You have to create BEFORE INSERT OR UPDATE trigger using function
autoinc(). You have to specify as function arguments: column name
(of int4 type) for which you want to get this feature and name of
SEQUENCE from which next value has to be fetched when NULL or 0
value is being inserted into column (, ... - you are able to specify
as many column/sequence pairs as you need).
There is example in autoinc.example.
To CREATE FUNCTION use autoinc.sql (will be made by gmake from
autoinc.source).

100
contrib/spi/autoinc.c Normal file
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@ -0,0 +1,100 @@
#include "executor/spi.h" /* this is what you need to work with SPI */
#include "commands/trigger.h" /* -"- and triggers */
HeapTuple autoinc(void);
extern int4 nextval(struct varlena * seqin);
HeapTuple
autoinc()
{
Trigger *trigger; /* to get trigger name */
int nargs; /* # of arguments */
int *chattrs; /* attnums of attributes to change */
int chnattrs = 0; /* # of above */
Datum *newvals; /* vals of above */
char **args; /* arguments */
char *relname; /* triggered relation name */
Relation rel; /* triggered relation */
HeapTuple rettuple = NULL;
TupleDesc tupdesc; /* tuple description */
bool isnull;
int i;
if (!CurrentTriggerData)
elog(WARN, "autoinc: triggers are not initialized");
if (TRIGGER_FIRED_FOR_STATEMENT(CurrentTriggerData->tg_event))
elog(WARN, "autoinc: can't process STATEMENT events");
if (TRIGGER_FIRED_AFTER(CurrentTriggerData->tg_event))
elog(WARN, "autoinc: must be fired before event");
if (TRIGGER_FIRED_BY_INSERT(CurrentTriggerData->tg_event))
rettuple = CurrentTriggerData->tg_trigtuple;
else if (TRIGGER_FIRED_BY_UPDATE(CurrentTriggerData->tg_event))
rettuple = CurrentTriggerData->tg_newtuple;
else
elog(WARN, "autoinc: can't process DELETE events");
rel = CurrentTriggerData->tg_relation;
relname = SPI_getrelname(rel);
trigger = CurrentTriggerData->tg_trigger;
nargs = trigger->tgnargs;
if (nargs <= 0 || nargs % 2 != 0)
elog(WARN, "autoinc (%s): even number gt 0 of arguments was expected", relname);
args = trigger->tgargs;
tupdesc = rel->rd_att;
CurrentTriggerData = NULL;
chattrs = (int *) palloc (nargs/2 * sizeof (int));
newvals = (Datum *) palloc (nargs/2 * sizeof (Datum));
for (i = 0; i < nargs; )
{
struct varlena *seqname;
int attnum = SPI_fnumber (tupdesc, args[i]);
int32 val;
if ( attnum < 0 )
elog(WARN, "autoinc (%s): there is no attribute %s", relname, args[i]);
if (SPI_gettypeid (tupdesc, attnum) != INT4OID)
elog(WARN, "autoinc (%s): attribute %s must be of INT4 type",
relname, args[i]);
val = DatumGetInt32 (SPI_getbinval (rettuple, tupdesc, attnum, &isnull));
if (!isnull && val != 0)
{
i += 2;
continue;
}
i++;
chattrs[chnattrs] = attnum;
seqname = textin (args[i]);
newvals[chnattrs] = Int32GetDatum (nextval (seqname));
if ( DatumGetInt32 (newvals[chnattrs]) == 0 )
newvals[chnattrs] = Int32GetDatum (nextval (seqname));
pfree (seqname);
chnattrs++;
i++;
}
if (chnattrs > 0)
{
rettuple = SPI_modifytuple (rel, rettuple, chnattrs, chattrs, newvals, NULL);
if ( rettuple == NULL )
elog (WARN, "autoinc (%s): %d returned by SPI_modifytuple",
relname, SPI_result);
}
pfree (relname);
pfree (chattrs);
pfree (newvals);
return (rettuple);
}

35
contrib/spi/autoinc.example Normal file
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@ -0,0 +1,35 @@
DROP SEQUENCE next_id;
DROP TABLE ids;
CREATE SEQUENCE next_id START -2 MINVALUE -2;
CREATE TABLE ids (
id int4,
idesc text
);
CREATE TRIGGER ids_nextid
BEFORE INSERT OR UPDATE ON ids
FOR EACH ROW
EXECUTE PROCEDURE autoinc (id, next_id);
INSERT INTO ids VALUES (0, 'first (-2 ?)');
INSERT INTO ids VALUES (null, 'second (-1 ?)');
INSERT INTO ids(idesc) VALUES ('third (1 ?!)');
SELECT * FROM ids;
UPDATE ids SET id = null, idesc = 'first: -2 --> 2'
WHERE idesc = 'first (-2 ?)';
UPDATE ids SET id = 0, idesc = 'second: -1 --> 3'
WHERE id = -1;
UPDATE ids SET id = 4, idesc = 'third: 1 --> 4'
WHERE id = 1;
SELECT * FROM ids;
SELECT 'Wasn''t it 4 ?' as nextval, nextval ('next_id') as value;
insert into ids (idesc) select textcat (idesc, '. Copy.') from ids;
SELECT * FROM ids;

6
contrib/spi/autoinc.source Normal file
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@ -0,0 +1,6 @@
DROP FUNCTION autoinc();
CREATE FUNCTION autoinc()
RETURNS opaque
AS '_OBJWD_/autoinc_DLSUFFIX_'
LANGUAGE 'c';

50
contrib/spi/timetravel.c
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@ -38,6 +38,8 @@ static EPlan *find_plan(char *ident, EPlan ** eplan, int *nplans);
* 2. IF an delete affects tuple with stop_date eq INFINITY
* then insert the same tuple with stop_date eq current date
* ELSE - skip deletion of tuple.
* 3. On INSERT, if start_date is NULL then current date will be
* inserted, if stop_date is NULL then INFINITY will be inserted.
*
* In CREATE TRIGGER you are to specify start_date and stop_date column
* names:
@ -65,6 +67,7 @@ timetravel()
EPlan *plan; /* prepared plan */
char ident[2 * NAMEDATALEN];
bool isnull; /* to know is some column NULL or not */
bool isinsert = false;
int ret;
int i;
@ -86,7 +89,7 @@ timetravel()
/* INSERT ? */
if (TRIGGER_FIRED_BY_INSERT(CurrentTriggerData->tg_event))
elog (WARN, "timetravel: can't process INSERT event");
isinsert = true;
if (TRIGGER_FIRED_BY_UPDATE(CurrentTriggerData->tg_event))
newtuple = CurrentTriggerData->tg_newtuple;
@ -133,6 +136,50 @@ timetravel()
relname, args[0], args[1]);
}
if (isinsert) /* INSERT */
{
int chnattrs = 0;
int chattrs[2];
Datum newvals[2];
oldon = SPI_getbinval (trigtuple, tupdesc, attnum[0], &isnull);
if (isnull)
{
newvals[chnattrs] = GetCurrentAbsoluteTime ();
chattrs[chnattrs] = attnum[0];
chnattrs++;
}
oldoff = SPI_getbinval (trigtuple, tupdesc, attnum[1], &isnull);
if (isnull)
{
if ((chnattrs == 0 && DatumGetInt32 (oldon) >= NOEND_ABSTIME) ||
(chnattrs > 0 && DatumGetInt32 (newvals[0]) >= NOEND_ABSTIME))
elog (WARN, "timetravel (%s): %s ge %s",
relname, args[0], args[1]);
newvals[chnattrs] = NOEND_ABSTIME;
chattrs[chnattrs] = attnum[1];
chnattrs++;
}
else
{
if ((chnattrs == 0 && DatumGetInt32 (oldon) >=
DatumGetInt32 (oldoff)) ||
(chnattrs > 0 && DatumGetInt32 (newvals[0]) >=
DatumGetInt32 (oldoff)))
elog (WARN, "timetravel (%s): %s ge %s",
relname, args[0], args[1]);
}
pfree (relname);
if ( chnattrs <= 0 )
return (trigtuple);
rettuple = SPI_modifytuple (rel, trigtuple, chnattrs,
chattrs, newvals, NULL);
return (rettuple);
}
oldon = SPI_getbinval (trigtuple, tupdesc, attnum[0], &isnull);
if (isnull)
elog(WARN, "timetravel (%s): %s must be NOT NULL", relname, args[0]);
@ -140,7 +187,6 @@ timetravel()
oldoff = SPI_getbinval (trigtuple, tupdesc, attnum[1], &isnull);
if (isnull)
elog(WARN, "timetravel (%s): %s must be NOT NULL", relname, args[1]);
/*
* If DELETE/UPDATE of tuple with stop_date neq INFINITY
* then say upper Executor to skip operation for this tuple

19
contrib/spi/timetravel.example
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@ -1,21 +1,26 @@
drop table tttest;
create table tttest (
price_id int4,
price_val int4,
price_on abstime default currabstime(),
price_off abstime default 'infinity'
price_on abstime,
price_off abstime
);
insert into tttest values (1, 1, null, null);
insert into tttest values (2, 2, null, null);
insert into tttest values (3, 3, null, null);
create trigger timetravel
before delete or update on tttest
before insert or delete or update on tttest
for each row
execute procedure
timetravel (price_on, price_off);
insert into tttest values (1, 1, null, null);
insert into tttest(price_id, price_val) values (2, 2);
insert into tttest(price_id, price_val,price_off) values (3, 3, 'infinity');
insert into tttest(price_id, price_val,price_off) values (3, 3,
datetime_abstime(datetime_mi_span('now', '100')));
insert into tttest(price_id, price_val,price_on) values (3, 3, 'infinity');
select * from tttest;
delete from tttest where price_id = 2;
select * from tttest;

6
contrib/spi/timetravel.source
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@ -1,12 +1,6 @@
DROP FUNCTION currabstime();
DROP FUNCTION timetravel();
DROP FUNCTION set_timetravel(name, int4);
CREATE FUNCTION currabstime()
RETURNS abstime
AS '_OBJWD_/timetravel_DLSUFFIX_'
LANGUAGE 'c';
CREATE FUNCTION timetravel()
RETURNS opaque
AS '_OBJWD_/timetravel_DLSUFFIX_'