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Provide the OR REPLACE option for CREATE TRIGGER. 

This is mostly straightforward.  However, we disallow replacing
constraint triggers or changing the is-constraint property; perhaps
that can be added later, but the complexity versus benefit tradeoff
doesn't look very good.

Also, no special thought is taken here for whether replacing an
existing trigger should result in changes to queued-but-not-fired
trigger actions.  We just document that if you're surprised by the
results, too bad, don't do that.  (Note that any such pending trigger
activity would have to be within the current session.)

Takamichi Osumi, reviewed at various times by Surafel Temesgen,
Peter Smith, and myself

Discussion: https://postgr.es/m/0DDF369B45A1B44B8A687ED43F06557C010BC362@G01JPEXMBYT03
This commit is contained in:
Tom Lane 2020-11-14 17:05:34 -05:00
parent dbca94510c
commit 92bf7e2d02
10 changed files with 408 additions and 114 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
doc/src/sgml/ref/create_trigger.sgml
View File

@ -26,7 +26,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
CREATE [ CONSTRAINT ] TRIGGER <replaceable class="parameter">name</replaceable> { BEFORE | AFTER | INSTEAD OF } { <replaceable class="parameter">event</replaceable> [ OR ... ] }
CREATE [ OR REPLACE ] [ CONSTRAINT ] TRIGGER <replaceable class="parameter">name</replaceable> { BEFORE | AFTER | INSTEAD OF } { <replaceable class="parameter">event</replaceable> [ OR ... ] }
ON <replaceable class="parameter">table_name</replaceable>
[ FROM <replaceable class="parameter">referenced_table_name</replaceable> ]
[ NOT DEFERRABLE | [ DEFERRABLE ] [ INITIALLY IMMEDIATE | INITIALLY DEFERRED ] ]
@ -48,13 +48,21 @@ CREATE [ CONSTRAINT ] TRIGGER <replaceable class="parameter">name</replaceable>
<title>Description</title>
<para>
<command>CREATE TRIGGER</command> creates a new trigger. The
<command>CREATE TRIGGER</command> creates a new trigger.
<command>CREATE OR REPLACE TRIGGER</command> will either create a
new trigger, or replace an existing trigger. The
trigger will be associated with the specified table, view, or foreign table
and will execute the specified
function <replaceable class="parameter">function_name</replaceable> when
certain operations are performed on that table.
</para>
<para>
To replace the current definition of an existing trigger, use
<command>CREATE OR REPLACE TRIGGER</command>, specifying the existing
trigger's name and parent table. All other properties are replaced.
</para>
<para>
The trigger can be specified to fire before the
operation is attempted on a row (before constraints are checked and
@ -436,7 +444,7 @@ UPDATE OF <replaceable>column_name1</replaceable> [, <replaceable>column_name2</
<title>Notes</title>
<para>
To create a trigger on a table, the user must have the
To create or replace a trigger on a table, the user must have the
<literal>TRIGGER</literal> privilege on the table. The user must
also have <literal>EXECUTE</literal> privilege on the trigger function.
</para>
@ -445,6 +453,17 @@ UPDATE OF <replaceable>column_name1</replaceable> [, <replaceable>column_name2</
Use <link linkend="sql-droptrigger"><command>DROP TRIGGER</command></link> to remove a trigger.
</para>
<para>
Creating a row-level trigger on a partitioned table will cause an
identical <quote>clone</quote> trigger to be created on each of its
existing partitions; and any partitions created or attached later will have
an identical trigger, too. If there is a conflictingly-named trigger on a
child partition already, an error occurs unless <command>CREATE OR REPLACE
TRIGGER</command> is used, in which case that trigger is replaced with a
clone trigger. When a partition is detached from its parent, its clone
triggers are removed.
</para>
<para>
A column-specific trigger (one defined using the <literal>UPDATE OF
<replaceable>column_name</replaceable></literal> syntax) will fire when any
@ -457,12 +476,6 @@ UPDATE OF <replaceable>column_name1</replaceable> [, <replaceable>column_name2</
value did not change.
</para>
<para>
There are a few built-in trigger functions that can be used to
solve common problems without having to write your own trigger code;
see <xref linkend="functions-trigger"/>.
</para>
<para>
In a <literal>BEFORE</literal> trigger, the <literal>WHEN</literal> condition is
evaluated just before the function is or would be executed, so using
@ -528,14 +541,6 @@ UPDATE OF <replaceable>column_name1</replaceable> [, <replaceable>column_name2</
the ones that are fired.
</para>
<para>
Creating a row-level trigger on a partitioned table will cause identical
triggers to be created in all its existing partitions; and any partitions
created or attached later will contain an identical trigger, too.
If the partition is detached from its parent, the trigger is removed.
Triggers on partitioned tables may not be <literal>INSTEAD OF</literal>.
</para>
<para>
Modifying a partitioned table or a table with inheritance children fires
statement-level triggers attached to the explicitly named table, but not
@ -546,9 +551,32 @@ UPDATE OF <replaceable>column_name1</replaceable> [, <replaceable>column_name2</
named by a <literal>REFERENCING</literal> clause, then before and after
images of rows are visible from all affected partitions or child tables.
In the case of inheritance children, the row images include only columns
that are present in the table that the trigger is attached to. Currently,
row-level triggers with transition relations cannot be defined on
partitions or inheritance child tables.
that are present in the table that the trigger is attached to.
</para>
<para>
Currently, row-level triggers with transition relations cannot be defined
on partitions or inheritance child tables. Also, triggers on partitioned
tables may not be <literal>INSTEAD OF</literal>.
</para>
<para>
Currently, the <literal>OR REPLACE</literal> option is not supported for
constraint triggers.
</para>
<para>
Replacing an existing trigger within a transaction that has already
performed updating actions on the trigger's table is not recommended.
Trigger firing decisions, or portions of firing decisions, that have
already been made will not be reconsidered, so the effects could be
surprising.
</para>
<para>
There are a few built-in trigger functions that can be used to
solve common problems without having to write your own trigger code;
see <xref linkend="functions-trigger"/>.
</para>
</refsect1>
@ -566,11 +594,12 @@ CREATE TRIGGER check_update
EXECUTE FUNCTION check_account_update();
</programlisting>
The same, but only execute the function if column <literal>balance</literal>
is specified as a target in the <command>UPDATE</command> command:
Modify that trigger definition to only execute the function if
column <literal>balance</literal> is specified as a target in
the <command>UPDATE</command> command:
<programlisting>
CREATE TRIGGER check_update
CREATE OR REPLACE TRIGGER check_update
BEFORE UPDATE OF balance ON accounts
FOR EACH ROW
EXECUTE FUNCTION check_account_update();
@ -728,6 +757,7 @@ CREATE TRIGGER paired_items_update
<command>CREATE CONSTRAINT TRIGGER</command> is a
<productname>PostgreSQL</productname> extension of the <acronym>SQL</acronym>
standard.
So is the <literal>OR REPLACE</literal> option.
</para>
</refsect1>

7
src/backend/catalog/index.c
View File

@ -2093,9 +2093,10 @@ index_constraint_create(Relation heapRelation,
*/
if (deferrable)
{
CreateTrigStmt *trigger;
CreateTrigStmt *trigger = makeNode(CreateTrigStmt);
trigger = makeNode(CreateTrigStmt);
trigger->replace = false;
trigger->isconstraint = true;
trigger->trigname = (constraintType == CONSTRAINT_PRIMARY) ?
"PK_ConstraintTrigger" :
"Unique_ConstraintTrigger";
@ -2107,7 +2108,7 @@ index_constraint_create(Relation heapRelation,
trigger->events = TRIGGER_TYPE_INSERT | TRIGGER_TYPE_UPDATE;
trigger->columns = NIL;
trigger->whenClause = NULL;
trigger->isconstraint = true;
trigger->transitionRels = NIL;
trigger->deferrable = true;
trigger->initdeferred = initdeferred;
trigger->constrrel = NULL;

28
src/backend/commands/tablecmds.c
View File

@ -10550,10 +10550,10 @@ CreateFKCheckTrigger(Oid myRelOid, Oid refRelOid, Constraint *fkconstraint,
* and "RI_ConstraintTrigger_c_NNNN" for the check triggers.
*/
fk_trigger = makeNode(CreateTrigStmt);
fk_trigger->replace = false;
fk_trigger->isconstraint = true;
fk_trigger->trigname = "RI_ConstraintTrigger_c";
fk_trigger->relation = NULL;
fk_trigger->row = true;
fk_trigger->timing = TRIGGER_TYPE_AFTER;
/* Either ON INSERT or ON UPDATE */
if (on_insert)
@ -10567,14 +10567,15 @@ CreateFKCheckTrigger(Oid myRelOid, Oid refRelOid, Constraint *fkconstraint,
fk_trigger->events = TRIGGER_TYPE_UPDATE;
}
fk_trigger->args = NIL;
fk_trigger->row = true;
fk_trigger->timing = TRIGGER_TYPE_AFTER;
fk_trigger->columns = NIL;
fk_trigger->transitionRels = NIL;
fk_trigger->whenClause = NULL;
fk_trigger->isconstraint = true;
fk_trigger->transitionRels = NIL;
fk_trigger->deferrable = fkconstraint->deferrable;
fk_trigger->initdeferred = fkconstraint->initdeferred;
fk_trigger->constrrel = NULL;
fk_trigger->args = NIL;
(void) CreateTrigger(fk_trigger, NULL, myRelOid, refRelOid, constraintOid,
indexOid, InvalidOid, InvalidOid, NULL, true, false);
@ -10599,15 +10600,17 @@ createForeignKeyActionTriggers(Relation rel, Oid refRelOid, Constraint *fkconstr
* DELETE action on the referenced table.
*/
fk_trigger = makeNode(CreateTrigStmt);
fk_trigger->replace = false;
fk_trigger->isconstraint = true;
fk_trigger->trigname = "RI_ConstraintTrigger_a";
fk_trigger->relation = NULL;
fk_trigger->args = NIL;
fk_trigger->row = true;
fk_trigger->timing = TRIGGER_TYPE_AFTER;
fk_trigger->events = TRIGGER_TYPE_DELETE;
fk_trigger->columns = NIL;
fk_trigger->transitionRels = NIL;
fk_trigger->whenClause = NULL;
fk_trigger->isconstraint = true;
fk_trigger->transitionRels = NIL;
fk_trigger->constrrel = NULL;
switch (fkconstraint->fk_del_action)
{
@ -10641,7 +10644,6 @@ createForeignKeyActionTriggers(Relation rel, Oid refRelOid, Constraint *fkconstr
(int) fkconstraint->fk_del_action);
break;
}
fk_trigger->args = NIL;
(void) CreateTrigger(fk_trigger, NULL, refRelOid, RelationGetRelid(rel),
constraintOid,
@ -10655,15 +10657,17 @@ createForeignKeyActionTriggers(Relation rel, Oid refRelOid, Constraint *fkconstr
* UPDATE action on the referenced table.
*/
fk_trigger = makeNode(CreateTrigStmt);
fk_trigger->replace = false;
fk_trigger->isconstraint = true;
fk_trigger->trigname = "RI_ConstraintTrigger_a";
fk_trigger->relation = NULL;
fk_trigger->args = NIL;
fk_trigger->row = true;
fk_trigger->timing = TRIGGER_TYPE_AFTER;
fk_trigger->events = TRIGGER_TYPE_UPDATE;
fk_trigger->columns = NIL;
fk_trigger->transitionRels = NIL;
fk_trigger->whenClause = NULL;
fk_trigger->isconstraint = true;
fk_trigger->transitionRels = NIL;
fk_trigger->constrrel = NULL;
switch (fkconstraint->fk_upd_action)
{
@ -10697,7 +10701,6 @@ createForeignKeyActionTriggers(Relation rel, Oid refRelOid, Constraint *fkconstr
(int) fkconstraint->fk_upd_action);
break;
}
fk_trigger->args = NIL;
(void) CreateTrigger(fk_trigger, NULL, refRelOid, RelationGetRelid(rel),
constraintOid,
@ -16898,6 +16901,8 @@ CloneRowTriggersToPartition(Relation parent, Relation partition)
}
trigStmt = makeNode(CreateTrigStmt);
trigStmt->replace = false;
trigStmt->isconstraint = OidIsValid(trigForm->tgconstraint);
trigStmt->trigname = NameStr(trigForm->tgname);
trigStmt->relation = NULL;
trigStmt->funcname = NULL; /* passed separately */
@ -16907,7 +16912,6 @@ CloneRowTriggersToPartition(Relation parent, Relation partition)
trigStmt->events = trigForm->tgtype & TRIGGER_TYPE_EVENT_MASK;
trigStmt->columns = cols;
trigStmt->whenClause = NULL; /* passed separately */
trigStmt->isconstraint = OidIsValid(trigForm->tgconstraint);
trigStmt->transitionRels = NIL; /* not supported at present */
trigStmt->deferrable = trigForm->tgdeferrable;
trigStmt->initdeferred = trigForm->tginitdeferred;

174
src/backend/commands/trigger.c
View File

@ -152,7 +152,9 @@ static bool before_stmt_triggers_fired(Oid relid, CmdType cmdType);
*
* When called on partitioned tables, this function recurses to create the
* trigger on all the partitions, except if isInternal is true, in which
* case caller is expected to execute recursion on its own.
* case caller is expected to execute recursion on its own. in_partition
* indicates such a recursive call; outside callers should pass "false"
* (but see CloneRowTriggersToPartition).
*/
ObjectAddress
CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
@ -171,12 +173,10 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
Relation rel;
AclResult aclresult;
Relation tgrel;
SysScanDesc tgscan;
ScanKeyData key;
Relation pgrel;
HeapTuple tuple;
HeapTuple tuple = NULL;
Oid funcrettype;
Oid trigoid;
Oid trigoid = InvalidOid;
char internaltrigname[NAMEDATALEN];
char *trigname;
Oid constrrelid = InvalidOid;
@ -185,6 +185,9 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
char *oldtablename = NULL;
char *newtablename = NULL;
bool partition_recurse;
bool trigger_exists = false;
Oid existing_constraint_oid = InvalidOid;
bool existing_isInternal = false;
if (OidIsValid(relOid))
rel = table_open(relOid, ShareRowExclusiveLock);
@ -688,6 +691,100 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
errmsg("function %s must return type %s",
NameListToString(stmt->funcname), "trigger")));
/*
* Scan pg_trigger to see if there is already a trigger of the same name.
* Skip this for internally generated triggers, since we'll modify the
* name to be unique below.
*
* NOTE that this is cool only because we have ShareRowExclusiveLock on
* the relation, so the trigger set won't be changing underneath us.
*/
tgrel = table_open(TriggerRelationId, RowExclusiveLock);
if (!isInternal)
{
ScanKeyData skeys[2];
SysScanDesc tgscan;
ScanKeyInit(&skeys[0],
Anum_pg_trigger_tgrelid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
ScanKeyInit(&skeys[1],
Anum_pg_trigger_tgname,
BTEqualStrategyNumber, F_NAMEEQ,
CStringGetDatum(stmt->trigname));
tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
NULL, 2, skeys);
/* There should be at most one matching tuple */
if (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
{
Form_pg_trigger oldtrigger = (Form_pg_trigger) GETSTRUCT(tuple);
trigoid = oldtrigger->oid;
existing_constraint_oid = oldtrigger->tgconstraint;
existing_isInternal = oldtrigger->tgisinternal;
trigger_exists = true;
/* copy the tuple to use in CatalogTupleUpdate() */
tuple = heap_copytuple(tuple);
}
systable_endscan(tgscan);
}
if (!trigger_exists)
{
/* Generate the OID for the new trigger. */
trigoid = GetNewOidWithIndex(tgrel, TriggerOidIndexId,
Anum_pg_trigger_oid);
}
else
{
/*
* If OR REPLACE was specified, we'll replace the old trigger;
* otherwise complain about the duplicate name.
*/
if (!stmt->replace)
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("trigger \"%s\" for relation \"%s\" already exists",
stmt->trigname, RelationGetRelationName(rel))));
/*
* An internal trigger cannot be replaced by a user-defined trigger.
* However, skip this test when in_partition, because then we're
* recursing from a partitioned table and the check was made at the
* parent level. Child triggers will always be marked "internal" (so
* this test does protect us from the user trying to replace a child
* trigger directly).
*/
if (existing_isInternal && !isInternal && !in_partition)
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("trigger \"%s\" for relation \"%s\" is an internal trigger",
stmt->trigname, RelationGetRelationName(rel))));
/*
* It is not allowed to replace with a constraint trigger; gram.y
* should have enforced this already.
*/
Assert(!stmt->isconstraint);
/*
* It is not allowed to replace an existing constraint trigger,
* either. (The reason for these restrictions is partly that it seems
* difficult to deal with pending trigger events in such cases, and
* partly that the command might imply changing the constraint's
* properties as well, which doesn't seem nice.)
*/
if (OidIsValid(existing_constraint_oid))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("trigger \"%s\" for relation \"%s\" is a constraint trigger",
stmt->trigname, RelationGetRelationName(rel))));
}
/*
* If it's a user-entered CREATE CONSTRAINT TRIGGER command, make a
* corresponding pg_constraint entry.
@ -727,15 +824,6 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
isInternal); /* is_internal */
}
/*
* Generate the trigger's OID now, so that we can use it in the name if
* needed.
*/
tgrel = table_open(TriggerRelationId, RowExclusiveLock);
trigoid = GetNewOidWithIndex(tgrel, TriggerOidIndexId,
Anum_pg_trigger_oid);
/*
* If trigger is internally generated, modify the provided trigger name to
* ensure uniqueness by appending the trigger OID. (Callers will usually
@ -753,37 +841,6 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
trigname = stmt->trigname;
}
/*
* Scan pg_trigger for existing triggers on relation. We do this only to
* give a nice error message if there's already a trigger of the same
* name. (The unique index on tgrelid/tgname would complain anyway.) We
* can skip this for internally generated triggers, since the name
* modification above should be sufficient.
*
* NOTE that this is cool only because we have ShareRowExclusiveLock on
* the relation, so the trigger set won't be changing underneath us.
*/
if (!isInternal)
{
ScanKeyInit(&key,
Anum_pg_trigger_tgrelid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
tgscan = systable_beginscan(tgrel, TriggerRelidNameIndexId, true,
NULL, 1, &key);
while (HeapTupleIsValid(tuple = systable_getnext(tgscan)))
{
Form_pg_trigger pg_trigger = (Form_pg_trigger) GETSTRUCT(tuple);
if (namestrcmp(&(pg_trigger->tgname), trigname) == 0)
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("trigger \"%s\" for relation \"%s\" already exists",
trigname, RelationGetRelationName(rel))));
}
systable_endscan(tgscan);
}
/*
* Build the new pg_trigger tuple.
*
@ -910,14 +967,24 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
else
nulls[Anum_pg_trigger_tgnewtable - 1] = true;
tuple = heap_form_tuple(tgrel->rd_att, values, nulls);
/*
* Insert tuple into pg_trigger.
* Insert or replace tuple in pg_trigger.
*/
CatalogTupleInsert(tgrel, tuple);
if (!trigger_exists)
{
tuple = heap_form_tuple(tgrel->rd_att, values, nulls);
CatalogTupleInsert(tgrel, tuple);
}
else
{
HeapTuple newtup;
heap_freetuple(tuple);
newtup = heap_form_tuple(tgrel->rd_att, values, nulls);
CatalogTupleUpdate(tgrel, &tuple->t_self, newtup);
heap_freetuple(newtup);
}
heap_freetuple(tuple); /* free either original or new tuple */
table_close(tgrel, RowExclusiveLock);
pfree(DatumGetPointer(values[Anum_pg_trigger_tgname - 1]));
@ -952,6 +1019,13 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
heap_freetuple(tuple);
table_close(pgrel, RowExclusiveLock);
/*
* If we're replacing a trigger, flush all the old dependencies before
* recording new ones.
*/
if (trigger_exists)
deleteDependencyRecordsFor(TriggerRelationId, trigoid, true);
/*
* Record dependencies for trigger. Always place a normal dependency on
* the function.

3
src/backend/nodes/copyfuncs.c
View File

@ -4304,6 +4304,8 @@ _copyCreateTrigStmt(const CreateTrigStmt *from)
{
CreateTrigStmt *newnode = makeNode(CreateTrigStmt);
COPY_SCALAR_FIELD(replace);
COPY_SCALAR_FIELD(isconstraint);
COPY_STRING_FIELD(trigname);
COPY_NODE_FIELD(relation);
COPY_NODE_FIELD(funcname);
@ -4313,7 +4315,6 @@ _copyCreateTrigStmt(const CreateTrigStmt *from)
COPY_SCALAR_FIELD(events);
COPY_NODE_FIELD(columns);
COPY_NODE_FIELD(whenClause);
COPY_SCALAR_FIELD(isconstraint);
COPY_NODE_FIELD(transitionRels);
COPY_SCALAR_FIELD(deferrable);
COPY_SCALAR_FIELD(initdeferred);

3
src/backend/nodes/equalfuncs.c
View File

@ -2011,6 +2011,8 @@ _equalCreateAmStmt(const CreateAmStmt *a, const CreateAmStmt *b)
static bool
_equalCreateTrigStmt(const CreateTrigStmt *a, const CreateTrigStmt *b)
{
COMPARE_SCALAR_FIELD(replace);
COMPARE_SCALAR_FIELD(isconstraint);
COMPARE_STRING_FIELD(trigname);
COMPARE_NODE_FIELD(relation);
COMPARE_NODE_FIELD(funcname);
@ -2020,7 +2022,6 @@ _equalCreateTrigStmt(const CreateTrigStmt *a, const CreateTrigStmt *b)
COMPARE_SCALAR_FIELD(events);
COMPARE_NODE_FIELD(columns);
COMPARE_NODE_FIELD(whenClause);
COMPARE_SCALAR_FIELD(isconstraint);
COMPARE_NODE_FIELD(transitionRels);
COMPARE_SCALAR_FIELD(deferrable);
COMPARE_SCALAR_FIELD(initdeferred);

52
src/backend/parser/gram.y
View File

@ -5218,48 +5218,54 @@ am_type:
*****************************************************************************/
CreateTrigStmt:
CREATE TRIGGER name TriggerActionTime TriggerEvents ON
CREATE opt_or_replace TRIGGER name TriggerActionTime TriggerEvents ON
qualified_name TriggerReferencing TriggerForSpec TriggerWhen
EXECUTE FUNCTION_or_PROCEDURE func_name '(' TriggerFuncArgs ')'
{
CreateTrigStmt *n = makeNode(CreateTrigStmt);
n->trigname = $3;
n->relation = $7;
n->funcname = $13;
n->args = $15;
n->row = $9;
n->timing = $4;
n->events = intVal(linitial($5));
n->columns = (List *) lsecond($5);
n->whenClause = $10;
n->transitionRels = $8;
n->isconstraint = false;
n->replace = $2;
n->isconstraint = false;
n->trigname = $4;
n->relation = $8;
n->funcname = $14;
n->args = $16;
n->row = $10;
n->timing = $5;
n->events = intVal(linitial($6));
n->columns = (List *) lsecond($6);
n->whenClause = $11;
n->transitionRels = $9;
n->deferrable = false;
n->initdeferred = false;
n->constrrel = NULL;
$$ = (Node *)n;
}
| CREATE CONSTRAINT TRIGGER name AFTER TriggerEvents ON
| CREATE opt_or_replace CONSTRAINT TRIGGER name AFTER TriggerEvents ON
qualified_name OptConstrFromTable ConstraintAttributeSpec
FOR EACH ROW TriggerWhen
EXECUTE FUNCTION_or_PROCEDURE func_name '(' TriggerFuncArgs ')'
{
CreateTrigStmt *n = makeNode(CreateTrigStmt);
n->trigname = $4;
n->relation = $8;
n->funcname = $17;
n->args = $19;
n->replace = $2;
if (n->replace) /* not supported, see CreateTrigger */
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("CREATE OR REPLACE CONSTRAINT TRIGGER is not supported")));
n->isconstraint = true;
n->trigname = $5;
n->relation = $9;
n->funcname = $18;
n->args = $20;
n->row = true;
n->timing = TRIGGER_TYPE_AFTER;
n->events = intVal(linitial($6));
n->columns = (List *) lsecond($6);
n->whenClause = $14;
n->events = intVal(linitial($7));
n->columns = (List *) lsecond($7);
n->whenClause = $15;
n->transitionRels = NIL;
n->isconstraint = true;
processCASbits($10, @10, "TRIGGER",
processCASbits($11, @11, "TRIGGER",
&n->deferrable, &n->initdeferred, NULL,
NULL, yyscanner);
n->constrrel = $9;
n->constrrel = $10;
$$ = (Node *)n;
}
;

3
src/include/nodes/parsenodes.h
View File

@ -2425,6 +2425,8 @@ typedef struct CreateAmStmt
typedef struct CreateTrigStmt
{
NodeTag type;
bool replace; /* replace trigger if already exists */
bool isconstraint; /* This is a constraint trigger */
char *trigname; /* TRIGGER's name */
RangeVar *relation; /* relation trigger is on */
List *funcname; /* qual. name of function to call */
@ -2436,7 +2438,6 @@ typedef struct CreateTrigStmt
int16 events; /* "OR" of INSERT/UPDATE/DELETE/TRUNCATE */
List *columns; /* column names, or NIL for all columns */
Node *whenClause; /* qual expression, or NULL if none */
bool isconstraint; /* This is a constraint trigger */
/* explicitly named transition data */
List *transitionRels; /* TriggerTransition nodes, or NIL if none */
/* The remaining fields are only used for constraint triggers */

89
src/test/regress/expected/triggers.out
View File

@ -3153,6 +3153,95 @@ drop table self_ref;
drop function dump_insert();
drop function dump_update();
drop function dump_delete();
--
-- Tests for CREATE OR REPLACE TRIGGER
--
create table my_table (id integer);
create function funcA() returns trigger as $$
begin
raise notice 'hello from funcA';
return null;
end; $$ language plpgsql;
create function funcB() returns trigger as $$
begin
raise notice 'hello from funcB';
return null;
end; $$ language plpgsql;
create trigger my_trig
after insert on my_table
for each row execute procedure funcA();
create trigger my_trig
before insert on my_table
for each row execute procedure funcB(); -- should fail
ERROR: trigger "my_trig" for relation "my_table" already exists
insert into my_table values (1);
NOTICE: hello from funcA
create or replace trigger my_trig
before insert on my_table
for each row execute procedure funcB(); -- OK
insert into my_table values (2); -- this insert should become a no-op
NOTICE: hello from funcB
table my_table;
id
----
1
(1 row)
drop table my_table;
-- test CREATE OR REPLACE TRIGGER on partition table
create table parted_trig (a int) partition by range (a);
create table parted_trig_1 partition of parted_trig
for values from (0) to (1000) partition by range (a);
create table parted_trig_1_1 partition of parted_trig_1 for values from (0) to (100);
create table parted_trig_2 partition of parted_trig for values from (1000) to (2000);
create table default_parted_trig partition of parted_trig default;
-- test that trigger can be replaced by another one
-- at the same level of partition table
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcA();
insert into parted_trig (a) values (50);
NOTICE: hello from funcA
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcB();
insert into parted_trig (a) values (50);
NOTICE: hello from funcB
-- test that child trigger cannot be replaced directly
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcA();
insert into parted_trig (a) values (50);
NOTICE: hello from funcA
create or replace trigger my_trig
after insert on parted_trig_1
for each row execute procedure funcB(); -- should fail
ERROR: trigger "my_trig" for relation "parted_trig_1" is an internal trigger
insert into parted_trig (a) values (50);
NOTICE: hello from funcA
drop trigger my_trig on parted_trig;
insert into parted_trig (a) values (50);
-- test that user trigger can be overwritten by one defined at upper level
create trigger my_trig
after insert on parted_trig_1
for each row execute procedure funcA();
insert into parted_trig (a) values (50);
NOTICE: hello from funcA
create trigger my_trig
after insert on parted_trig
for each row execute procedure funcB(); -- should fail
ERROR: trigger "my_trig" for relation "parted_trig_1" already exists
insert into parted_trig (a) values (50);
NOTICE: hello from funcA
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcB();
insert into parted_trig (a) values (50);
NOTICE: hello from funcB
-- cleanup
drop table parted_trig;
drop function funcA();
drop function funcB();
-- Leave around some objects for other tests
create table trigger_parted (a int primary key) partition by list (a);
create function trigger_parted_trigfunc() returns trigger language plpgsql as

87
src/test/regress/sql/triggers.sql
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@ -2348,6 +2348,93 @@ drop function dump_insert();
drop function dump_update();
drop function dump_delete();
--
-- Tests for CREATE OR REPLACE TRIGGER
--
create table my_table (id integer);
create function funcA() returns trigger as $$
begin
raise notice 'hello from funcA';
return null;
end; $$ language plpgsql;
create function funcB() returns trigger as $$
begin
raise notice 'hello from funcB';
return null;
end; $$ language plpgsql;
create trigger my_trig
after insert on my_table
for each row execute procedure funcA();
create trigger my_trig
before insert on my_table
for each row execute procedure funcB(); -- should fail
insert into my_table values (1);
create or replace trigger my_trig
before insert on my_table
for each row execute procedure funcB(); -- OK
insert into my_table values (2); -- this insert should become a no-op
table my_table;
drop table my_table;
-- test CREATE OR REPLACE TRIGGER on partition table
create table parted_trig (a int) partition by range (a);
create table parted_trig_1 partition of parted_trig
for values from (0) to (1000) partition by range (a);
create table parted_trig_1_1 partition of parted_trig_1 for values from (0) to (100);
create table parted_trig_2 partition of parted_trig for values from (1000) to (2000);
create table default_parted_trig partition of parted_trig default;
-- test that trigger can be replaced by another one
-- at the same level of partition table
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcA();
insert into parted_trig (a) values (50);
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcB();
insert into parted_trig (a) values (50);
-- test that child trigger cannot be replaced directly
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcA();
insert into parted_trig (a) values (50);
create or replace trigger my_trig
after insert on parted_trig_1
for each row execute procedure funcB(); -- should fail
insert into parted_trig (a) values (50);
drop trigger my_trig on parted_trig;
insert into parted_trig (a) values (50);
-- test that user trigger can be overwritten by one defined at upper level
create trigger my_trig
after insert on parted_trig_1
for each row execute procedure funcA();
insert into parted_trig (a) values (50);
create trigger my_trig
after insert on parted_trig
for each row execute procedure funcB(); -- should fail
insert into parted_trig (a) values (50);
create or replace trigger my_trig
after insert on parted_trig
for each row execute procedure funcB();
insert into parted_trig (a) values (50);
-- cleanup
drop table parted_trig;
drop function funcA();
drop function funcB();
-- Leave around some objects for other tests
create table trigger_parted (a int primary key) partition by list (a);
create function trigger_parted_trigfunc() returns trigger language plpgsql as