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Improve documentation of trigger firing queue handling, cleanup.

Browse source 
Neil Conway
This commit is contained in:
Bruce Momjian 2002-08-17 12:15:49 +00:00
parent 2132ac89bf
commit b813554dbd
5 changed files with 319 additions and 181 deletions
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38
doc/src/sgml/ref/set_constraints.sgml
View file

@ -1,4 +1,4 @@
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.4 2002/06/03 01:10:38 momjian Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.5 2002/08/17 12:15:48 momjian Exp $ -->
<refentry id="SQL-SET-CONSTRAINTS">
<refmeta>
<refentrytitle id="SQL-SET-CONSTRAINTS-title">SET CONSTRAINTS</refentrytitle>
@ -22,10 +22,32 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">constraint</replaceable>
<para>
<command>SET CONSTRAINTS</command> sets the behavior of constraint
evaluation in the current transaction. In
<option>IMMEDIATE</option> mode, constraints are checked at the end
of each statement. In <option>DEFERRED</option> mode, constraints
are not checked until transaction commit.
evaluation in the current transaction. In <option>IMMEDIATE
</option> mode, constraints are checked at the end of each
statement. In <option>DEFERRED</option> mode, constraints are not
checked until transaction commit.
</para>
<note>
<para>
This command only alters the behavior of constraints within the
current transaction. Thus, if you execute this command outside
of an explicit transaction block (such as one started with
<command>BEGIN</command>), it will not appear to have any effect.
If you wish to change the behavior of a constraint without needing
to issue a <command>SET CONSTRAINTS</command> command in every
transaction, specify <option>INITIALLY DEFERRED</option> or
<option>INITIALLY IMMEDIATE</option> when you create the constraint.
</para>
</note>
<para>
When you change the mode of a constraint to be <option>IMMEDIATE
</option>, the new constraint mode takes effect retroactively:
any outstanding data modifications that would have been checked
at the end of the transaction (when using
<option>DEFERRED</option>) are instead checked during the
execution of the <command>SET CONSTRAINTS</command> command.
</para>
<para>
@ -52,7 +74,11 @@ SET CONSTRAINTS { ALL | <replaceable class="parameter">constraint</replaceable>
<para>
<command>SET CONSTRAINTS</command> is defined in
<acronym>SQL92</acronym> and <acronym>SQL99</acronym>.
<acronym>SQL92</acronym> and <acronym>SQL99</acronym>. The
implementation in <productname>PostgreSQL</productname> complies
with the behavior defined in the standard, except for the
<productname>PostgreSQL</productname> limitation that <command>SET
CONSTRAINTS</command> cannot be applied to check or unique constraints.
</para>
</refsect2>
</refsect1>

287
src/backend/commands/trigger.c
View file

@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.125 2002/08/13 17:22:08 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.126 2002/08/17 12:15:48 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -1266,12 +1266,10 @@ static MemoryContext deftrig_cxt = NULL;
* state IMMEDIATE or DEFERRED.
* ----------
*/
static bool deftrig_dfl_all_isset = false;
static bool deftrig_dfl_all_isdeferred = false;
static List *deftrig_dfl_trigstates = NIL;
static bool deftrig_all_isset;
static bool deftrig_all_isdeferred;
static bool deftrig_all_isset = false;
static bool deftrig_all_isdeferred = false;
static List *deftrig_trigstates;
/* ----------
@ -1702,8 +1700,11 @@ DeferredTriggerBeginXact(void)
ALLOCSET_DEFAULT_MAXSIZE);
oldcxt = MemoryContextSwitchTo(deftrig_cxt);
deftrig_all_isset = deftrig_dfl_all_isset;
deftrig_all_isdeferred = deftrig_dfl_all_isdeferred;
deftrig_all_isset = false;
/*
* If unspecified, constraints default to IMMEDIATE, per SQL
*/
deftrig_all_isdeferred = false;
deftrig_trigstates = NIL;
foreach(l, deftrig_dfl_trigstates)
@ -1793,189 +1794,125 @@ DeferredTriggerAbortXact(void)
/* ----------
* DeferredTriggerSetState()
*
* Called for the users SET CONSTRAINTS ... utility command.
* Called for the SET CONSTRAINTS ... utility command.
* ----------
*/
void
DeferredTriggerSetState(ConstraintsSetStmt *stmt)
{
Relation tgrel;
List *l;
List *ls;
List *loid = NIL;
MemoryContext oldcxt;
bool found;
DeferredTriggerStatus state;
/*
* If called outside a transaction block, we can safely return: this
* command cannot effect any subsequent transactions, and there
* are no "session-level" trigger settings.
*/
if (!IsTransactionBlock())
return;
/*
* Handle SET CONSTRAINTS ALL ...
*/
if (stmt->constraints == NIL)
{
if (!IsTransactionBlock())
/*
* Drop all per-transaction information about individual trigger
* states.
*/
l = deftrig_trigstates;
while (l != NIL)
{
/*
* ... outside of a transaction block
*
* Drop all information about individual trigger states per
* session.
*/
l = deftrig_dfl_trigstates;
while (l != NIL)
{
List *next = lnext(l);
List *next = lnext(l);
pfree(lfirst(l));
pfree(l);
l = next;
}
deftrig_dfl_trigstates = NIL;
/*
* Set the session ALL state to known.
*/
deftrig_dfl_all_isset = true;
deftrig_dfl_all_isdeferred = stmt->deferred;
return;
pfree(lfirst(l));
pfree(l);
l = next;
}
else
{
/*
* ... inside of a transaction block
*
* Drop all information about individual trigger states per
* transaction.
*/
l = deftrig_trigstates;
while (l != NIL)
{
List *next = lnext(l);
pfree(lfirst(l));
pfree(l);
l = next;
}
deftrig_trigstates = NIL;
/*
* Set the per transaction ALL state to known.
*/
deftrig_all_isset = true;
deftrig_all_isdeferred = stmt->deferred;
return;
}
}
/* ----------
* Handle SET CONSTRAINTS constraint-name [, ...]
* First lookup all trigger Oid's for the constraint names.
* ----------
*/
tgrel = heap_openr(TriggerRelationName, AccessShareLock);
foreach(l, stmt->constraints)
{
char *cname = strVal(lfirst(l));
ScanKeyData skey;
SysScanDesc tgscan;
HeapTuple htup;
deftrig_trigstates = NIL;
/*
* Check that only named constraints are set explicitly
* Set the per-transaction ALL state to known.
*/
if (strlen(cname) == 0)
elog(ERROR, "unnamed constraints cannot be set explicitly");
/*
* Setup to scan pg_trigger by tgconstrname ...
*/
ScanKeyEntryInitialize(&skey,
(bits16) 0x0,
(AttrNumber) Anum_pg_trigger_tgconstrname,
(RegProcedure) F_NAMEEQ,
PointerGetDatum(cname));
tgscan = systable_beginscan(tgrel, TriggerConstrNameIndex, true,
SnapshotNow, 1, &skey);
/*
* ... and search for the constraint trigger row
*/
found = false;
while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
{
Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);
Oid constr_oid;
/*
* If we found some, check that they fit the deferrability but
* skip ON <event> RESTRICT ones, since they are silently
* never deferrable.
*/
if (stmt->deferred && !pg_trigger->tgdeferrable &&
pg_trigger->tgfoid != F_RI_FKEY_RESTRICT_UPD &&
pg_trigger->tgfoid != F_RI_FKEY_RESTRICT_DEL)
elog(ERROR, "Constraint '%s' is not deferrable",
cname);
AssertTupleDescHasOid(tgrel->rd_att);
constr_oid = HeapTupleGetOid(htup);
loid = lappendi(loid, constr_oid);
found = true;
}
systable_endscan(tgscan);
/*
* Not found ?
*/
if (!found)
elog(ERROR, "Constraint '%s' does not exist", cname);
}
heap_close(tgrel, AccessShareLock);
if (!IsTransactionBlock())
{
/*
* Outside of a transaction block set the trigger states of
* individual triggers on session level.
*/
oldcxt = MemoryContextSwitchTo(deftrig_gcxt);
foreach(l, loid)
{
found = false;
foreach(ls, deftrig_dfl_trigstates)
{
state = (DeferredTriggerStatus) lfirst(ls);
if (state->dts_tgoid == (Oid) lfirsti(l))
{
state->dts_tgisdeferred = stmt->deferred;
found = true;
break;
}
}
if (!found)
{
state = (DeferredTriggerStatus)
palloc(sizeof(DeferredTriggerStatusData));
state->dts_tgoid = (Oid) lfirsti(l);
state->dts_tgisdeferred = stmt->deferred;
deftrig_dfl_trigstates =
lappend(deftrig_dfl_trigstates, state);
}
}
MemoryContextSwitchTo(oldcxt);
return;
deftrig_all_isset = true;
deftrig_all_isdeferred = stmt->deferred;
}
else
{
Relation tgrel;
MemoryContext oldcxt;
bool found;
DeferredTriggerStatus state;
List *ls;
List *loid = NIL;
/* ----------
* Handle SET CONSTRAINTS constraint-name [, ...]
* First lookup all trigger Oid's for the constraint names.
* ----------
*/
tgrel = heap_openr(TriggerRelationName, AccessShareLock);
foreach(l, stmt->constraints)
{
char *cname = strVal(lfirst(l));
ScanKeyData skey;
SysScanDesc tgscan;
HeapTuple htup;
/*
* Check that only named constraints are set explicitly
*/
if (strlen(cname) == 0)
elog(ERROR, "unnamed constraints cannot be set explicitly");
/*
* Setup to scan pg_trigger by tgconstrname ...
*/
ScanKeyEntryInitialize(&skey, (bits16) 0x0,
(AttrNumber) Anum_pg_trigger_tgconstrname,
(RegProcedure) F_NAMEEQ,
PointerGetDatum(cname));
tgscan = systable_beginscan(tgrel, TriggerConstrNameIndex, true,
SnapshotNow, 1, &skey);
/*
* ... and search for the constraint trigger row
*/
found = false;
while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
{
Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);
Oid constr_oid;
/*
* If we found some, check that they fit the deferrability but
* skip ON <event> RESTRICT ones, since they are silently
* never deferrable.
*/
if (stmt->deferred && !pg_trigger->tgdeferrable &&
pg_trigger->tgfoid != F_RI_FKEY_RESTRICT_UPD &&
pg_trigger->tgfoid != F_RI_FKEY_RESTRICT_DEL)
elog(ERROR, "Constraint '%s' is not deferrable",
cname);
AssertTupleDescHasOid(tgrel->rd_att);
constr_oid = HeapTupleGetOid(htup);
loid = lappendi(loid, constr_oid);
found = true;
}
systable_endscan(tgscan);
/*
* Not found ?
*/
if (!found)
elog(ERROR, "Constraint '%s' does not exist", cname);
}
heap_close(tgrel, AccessShareLock);
/*
* Inside of a transaction block set the trigger states of
* individual triggers on transaction level.
@ -2008,9 +1945,17 @@ DeferredTriggerSetState(ConstraintsSetStmt *stmt)
}
MemoryContextSwitchTo(oldcxt);
return;
}
/*
* SQL99 requires that when a constraint is set to IMMEDIATE, any
* deferred checks against that constraint must be made when the
* SET CONSTRAINTS command is executed -- i.e. the effects of the
* SET CONSTRAINTS command applies retroactively. This happens "for
* free" since we have already made the necessary modifications to
* the constraints, and deferredTriggerEndQuery() is called by
* finish_xact_command().
*/
}

7
src/backend/tcop/utility.c
View file

@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.170 2002/08/15 16:36:05 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.171 2002/08/17 12:15:49 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -215,9 +215,8 @@ ProcessUtility(Node *parsetree,
BeginTransactionBlock();
/*
* Currently, the only option that can be set is
* the transaction isolation level by START
* TRANSACTION.
* Currently, the only option that can be set by
* START TRANSACTION is the isolation level.
*/
if (stmt->options)
{

77
src/test/regress/expected/foreign_key.out
View file

@ -945,3 +945,80 @@ ERROR: Unable to identify an operator '=' for types 'inet' and 'integer'
drop table pktable;
ERROR: table "pktable" does not exist
drop table pktable_base;
--
-- Deferrable constraints
-- (right now, only FOREIGN KEY constraints can be deferred)
--
-- deferrable, explicitely deferred
CREATE TABLE pktable (
id INT4 PRIMARY KEY,
other INT4
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'pktable_pkey' for table 'pktable'
CREATE TABLE fktable (
id INT4 PRIMARY KEY,
fk INT4 REFERENCES pktable DEFERRABLE
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'fktable_pkey' for table 'fktable'
NOTICE: CREATE TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
-- default to immediate: should fail
INSERT INTO fktable VALUES (5, 10);
ERROR: $1 referential integrity violation - key referenced from fktable not found in pktable
-- explicitely defer the constraint
BEGIN;
SET CONSTRAINTS ALL DEFERRED;
INSERT INTO fktable VALUES (10, 15);
INSERT INTO pktable VALUES (15, 0); -- make the FK insert valid
COMMIT;
DROP TABLE fktable, pktable;
-- deferrable, initially deferred
CREATE TABLE pktable (
id INT4 PRIMARY KEY,
other INT4
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'pktable_pkey' for table 'pktable'
CREATE TABLE fktable (
id INT4 PRIMARY KEY,
fk INT4 REFERENCES pktable DEFERRABLE INITIALLY DEFERRED
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'fktable_pkey' for table 'fktable'
NOTICE: CREATE TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
-- default to deferred, should succeed
BEGIN;
INSERT INTO fktable VALUES (100, 200);
INSERT INTO pktable VALUES (200, 500); -- make the FK insert valid
COMMIT;
-- default to deferred, explicitely make immediate
BEGIN;
SET CONSTRAINTS ALL IMMEDIATE;
-- should fail
INSERT INTO fktable VALUES (500, 1000);
ERROR: $1 referential integrity violation - key referenced from fktable not found in pktable
COMMIT;
DROP TABLE fktable, pktable;
-- tricky behavior: according to SQL99, if a deferred constraint is set
-- to 'immediate' mode, it should be checked for validity *immediately*,
-- not when the current transaction commits (i.e. the mode change applies
-- retroactively)
CREATE TABLE pktable (
id INT4 PRIMARY KEY,
other INT4
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'pktable_pkey' for table 'pktable'
CREATE TABLE fktable (
id INT4 PRIMARY KEY,
fk INT4 REFERENCES pktable DEFERRABLE
);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index 'fktable_pkey' for table 'fktable'
NOTICE: CREATE TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
BEGIN;
SET CONSTRAINTS ALL DEFERRED;
-- should succeed, for now
INSERT INTO fktable VALUES (1000, 2000);
-- should cause transaction abort, due to preceding error
SET CONSTRAINTS ALL IMMEDIATE;
ERROR: $1 referential integrity violation - key referenced from fktable not found in pktable
INSERT INTO pktable VALUES (2000, 3); -- too late
ERROR: current transaction is aborted, queries ignored until end of transaction block
COMMIT;
DROP TABLE fktable, pktable;

91
src/test/regress/sql/foreign_key.sql
View file

@ -583,3 +583,94 @@ create table pktable(ptest1 inet, ptest2 inet, primary key(base1, ptest1), forei
drop table pktable;
drop table pktable_base;
--
-- Deferrable constraints
-- (right now, only FOREIGN KEY constraints can be deferred)
--
-- deferrable, explicitely deferred
CREATE TABLE pktable (
id INT4 PRIMARY KEY,
other INT4
);
CREATE TABLE fktable (
id INT4 PRIMARY KEY,
fk INT4 REFERENCES pktable DEFERRABLE
);
-- default to immediate: should fail
INSERT INTO fktable VALUES (5, 10);
-- explicitely defer the constraint
BEGIN;
SET CONSTRAINTS ALL DEFERRED;
INSERT INTO fktable VALUES (10, 15);
INSERT INTO pktable VALUES (15, 0); -- make the FK insert valid
COMMIT;
DROP TABLE fktable, pktable;
-- deferrable, initially deferred
CREATE TABLE pktable (
id INT4 PRIMARY KEY,
other INT4
);
CREATE TABLE fktable (
id INT4 PRIMARY KEY,
fk INT4 REFERENCES pktable DEFERRABLE INITIALLY DEFERRED
);
-- default to deferred, should succeed
BEGIN;
INSERT INTO fktable VALUES (100, 200);
INSERT INTO pktable VALUES (200, 500); -- make the FK insert valid
COMMIT;
-- default to deferred, explicitely make immediate
BEGIN;
SET CONSTRAINTS ALL IMMEDIATE;
-- should fail
INSERT INTO fktable VALUES (500, 1000);
COMMIT;
DROP TABLE fktable, pktable;
-- tricky behavior: according to SQL99, if a deferred constraint is set
-- to 'immediate' mode, it should be checked for validity *immediately*,
-- not when the current transaction commits (i.e. the mode change applies
-- retroactively)
CREATE TABLE pktable (
id INT4 PRIMARY KEY,
other INT4
);
CREATE TABLE fktable (
id INT4 PRIMARY KEY,
fk INT4 REFERENCES pktable DEFERRABLE
);
BEGIN;
SET CONSTRAINTS ALL DEFERRED;
-- should succeed, for now
INSERT INTO fktable VALUES (1000, 2000);
-- should cause transaction abort, due to preceding error
SET CONSTRAINTS ALL IMMEDIATE;
INSERT INTO pktable VALUES (2000, 3); -- too late
COMMIT;
DROP TABLE fktable, pktable;