Skip to content

P
Postgres FD Implementation
Commit b813554d authored by Bruce Momjian's avatar Bruce Momjian
Browse files
Options

Improve documentation of trigger firing queue handling, cleanup. 

Neil Conway
parent 2132ac89
Hide whitespace changes
Inline Side-by-side
Showing with 307 additions and 169 deletions
doc/src/sgml/ref/set_constraints.sgml
View file @ b813554d
<!-- $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>
......
src/backend/commands/trigger.c
View file @ b813554d
......@@ -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())
{
/*
* ... 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);
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;
}
else
/*
* Drop all per-transaction information about individual trigger
* states.
*/
l = deftrig_trigstates;
while (l != NIL)
{
/*
* ... 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;
List *next = lnext(l);
return;
pfree(lfirst(l));
pfree(l);
l = next;
}
}
/* ----------
* 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");
deftrig_trigstates = NIL;
/*
* Setup to scan pg_trigger by tgconstrname ...
* Set the per-transaction ALL state to known.
*/
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
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.
* ----------
*/
found = false;
tgrel = heap_openr(TriggerRelationName, AccessShareLock);
while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
foreach(l, stmt->constraints)
{
Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);
Oid constr_oid;
char *cname = strVal(lfirst(l));
ScanKeyData skey;
SysScanDesc tgscan;
HeapTuple htup;
/*
* If we found some, check that they fit the deferrability but
* skip ON <event> RESTRICT ones, since they are silently
* never deferrable.
* Check that only named constraints are set explicitly
*/
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);
if (strlen(cname) == 0)
elog(ERROR, "unnamed constraints cannot be set explicitly");
/*
* Not found ?
*/
if (!found)
elog(ERROR, "Constraint '%s' does not exist", cname);
}
heap_close(tgrel, AccessShareLock);
/*
* Setup to scan pg_trigger by tgconstrname ...
*/
ScanKeyEntryInitialize(&skey, (bits16) 0x0,
(AttrNumber) Anum_pg_trigger_tgconstrname,
(RegProcedure) F_NAMEEQ,
PointerGetDatum(cname));
if (!IsTransactionBlock())
{
/*
* Outside of a transaction block set the trigger states of
* individual triggers on session level.
*/
oldcxt = MemoryContextSwitchTo(deftrig_gcxt);
tgscan = systable_beginscan(tgrel, TriggerConstrNameIndex, true,
SnapshotNow, 1, &skey);
foreach(l, loid)
{
/*
* ... and search for the constraint trigger row
*/
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)
while (HeapTupleIsValid(htup = systable_getnext(tgscan)))
{
state = (DeferredTriggerStatus)
palloc(sizeof(DeferredTriggerStatusData));
state->dts_tgoid = (Oid) lfirsti(l);
state->dts_tgisdeferred = stmt->deferred;
Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(htup);
Oid constr_oid;
deftrig_dfl_trigstates =
lappend(deftrig_dfl_trigstates, state);
/*
* 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;
}
}
MemoryContextSwitchTo(oldcxt);
systable_endscan(tgscan);
/*
* Not found ?
*/
if (!found)
elog(ERROR, "Constraint '%s' does not exist", cname);
}
heap_close(tgrel, AccessShareLock);
return;
}
else
{
/*
* 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().
*/
}
......
src/backend/tcop/utility.c
View file @ b813554d
......@@ -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)
{
......
src/test/regress/expected/foreign_key.out
View file @ b813554d
......@@ -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;
src/test/regress/sql/foreign_key.sql
View file @ b813554d
......@@ -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;
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment