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Teach CREATE CONSTRAINT TRIGGER to convert old-style foreign key

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trigger definitions into regular foreign key constraints.  This seems
necessary given that some people evidently never did get around to
running adddepend on their schemas, and without some sort of hack the
old definitions will no longer work.  Per report from Olivier Prenant
and subsequent investigation.
REL8_3_STABLE
Tom Lane 18 years ago
parent 97ddfc9607
commit a2899ebdc2
1 changed files with 288 additions and 69 deletions
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  1. 357
      src/backend/commands/trigger.c

357
src/backend/commands/trigger.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.219 2007/09/12 22:10:26 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.220 2007/11/04 01:16:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -31,6 +31,7 @@
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "parser/parse_func.h"
#include "tcop/utility.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
@ -40,6 +41,12 @@
#include "utils/syscache.h"
/* GUC variables */
int SessionReplicationRole = SESSION_REPLICATION_ROLE_ORIGIN;
/* Local function prototypes */
static void ConvertTriggerToFK(CreateTrigStmt *stmt, Oid funcoid);
static void InsertTrigger(TriggerDesc *trigdesc, Trigger *trigger, int indx);
static HeapTuple GetTupleForTrigger(EState *estate,
ResultRelInfo *relinfo,
@ -54,20 +61,17 @@ static HeapTuple ExecCallTriggerFunc(TriggerData *trigdata,
static void AfterTriggerSaveEvent(ResultRelInfo *relinfo, int event,
bool row_trigger, HeapTuple oldtup, HeapTuple newtup);
/*
* SessionReplicationRole -
*
* Global variable that controls the trigger firing behaviour based
* on pg_trigger.tgenabled. This is maintained from misc/guc.c.
*/
int SessionReplicationRole = SESSION_REPLICATION_ROLE_ORIGIN;
/*
* Create a trigger. Returns the OID of the created trigger.
*
* constraintOid, if nonzero, says that this trigger is being created to
* implement that constraint. A suitable pg_depend entry will be made
* to link the trigger to that constraint.
* constraintOid, if nonzero, says that this trigger is being created
* internally to implement that constraint. A suitable pg_depend entry will
* be made to link the trigger to that constraint. constraintOid is zero when
* executing a user-entered CREATE TRIGGER command.
*
* Note: can return InvalidOid if we decided to not create a trigger at all,
* but a foreign-key constraint. This is a kluge for backwards compatibility.
*/
Oid
CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
@ -142,39 +146,6 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
RelationGetRelationName(rel));
}
/*
* Generate the trigger's OID now, so that we can use it in the name if
* needed.
*/
tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
trigoid = GetNewOid(tgrel);
/*
* If trigger is for an RI constraint, the passed-in name is the
* constraint name; save that and build a unique trigger name to avoid
* collisions with user-selected trigger names.
*/
if (OidIsValid(constraintOid))
{
snprintf(constrtrigname, sizeof(constrtrigname),
"RI_ConstraintTrigger_%u", trigoid);
trigname = constrtrigname;
constrname = stmt->trigname;
}
else if (stmt->isconstraint)
{
/* constraint trigger: trigger name is also constraint name */
trigname = stmt->trigname;
constrname = stmt->trigname;
}
else
{
/* regular trigger: use empty constraint name */
trigname = stmt->trigname;
constrname = "";
}
/* Compute tgtype */
TRIGGER_CLEAR_TYPE(tgtype);
if (stmt->before)
@ -214,6 +185,85 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
}
}
/*
* Find and validate the trigger function.
*/
funcoid = LookupFuncName(stmt->funcname, 0, fargtypes, false);
funcrettype = get_func_rettype(funcoid);
if (funcrettype != TRIGGEROID)
{
/*
* We allow OPAQUE just so we can load old dump files. When we see a
* trigger function declared OPAQUE, change it to TRIGGER.
*/
if (funcrettype == OPAQUEOID)
{
ereport(WARNING,
(errmsg("changing return type of function %s from \"opaque\" to \"trigger\"",
NameListToString(stmt->funcname))));
SetFunctionReturnType(funcoid, TRIGGEROID);
}
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("function %s must return type \"trigger\"",
NameListToString(stmt->funcname))));
}
/*
* If the command is a user-entered CREATE CONSTRAINT TRIGGER command
* that references one of the built-in RI_FKey trigger functions, assume
* it is from a dump of a pre-7.3 foreign key constraint, and take steps
* to convert this legacy representation into a regular foreign key
* constraint. Ugly, but necessary for loading old dump files.
*/
if (stmt->isconstraint && !OidIsValid(constraintOid) &&
stmt->constrrel != NULL &&
list_length(stmt->args) >= 6 &&
(list_length(stmt->args) % 2) == 0 &&
RI_FKey_trigger_type(funcoid) != RI_TRIGGER_NONE)
{
ConvertTriggerToFK(stmt, funcoid);
/* Keep lock on target rel until end of xact */
heap_close(rel, NoLock);
return InvalidOid;
}
/*
* Generate the trigger's OID now, so that we can use it in the name if
* needed.
*/
tgrel = heap_open(TriggerRelationId, RowExclusiveLock);
trigoid = GetNewOid(tgrel);
/*
* If trigger is for an RI constraint, the passed-in name is the
* constraint name; save that and build a unique trigger name to avoid
* collisions with user-selected trigger names.
*/
if (OidIsValid(constraintOid))
{
snprintf(constrtrigname, sizeof(constrtrigname),
"RI_ConstraintTrigger_%u", trigoid);
trigname = constrtrigname;
constrname = stmt->trigname;
}
else if (stmt->isconstraint)
{
/* constraint trigger: trigger name is also constraint name */
trigname = stmt->trigname;
constrname = stmt->trigname;
}
else
{
/* regular trigger: use empty constraint name */
trigname = stmt->trigname;
constrname = "";
}
/*
* Scan pg_trigger for existing triggers on relation. We do this mainly
* because we must count them; a secondary benefit is to give a nice error
@ -242,31 +292,6 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
}
systable_endscan(tgscan);
/*
* Find and validate the trigger function.
*/
funcoid = LookupFuncName(stmt->funcname, 0, fargtypes, false);
funcrettype = get_func_rettype(funcoid);
if (funcrettype != TRIGGEROID)
{
/*
* We allow OPAQUE just so we can load old dump files. When we see a
* trigger function declared OPAQUE, change it to TRIGGER.
*/
if (funcrettype == OPAQUEOID)
{
ereport(WARNING,
(errmsg("changing return type of function %s from \"opaque\" to \"trigger\"",
NameListToString(stmt->funcname))));
SetFunctionReturnType(funcoid, TRIGGEROID);
}
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("function %s must return type \"trigger\"",
NameListToString(stmt->funcname))));
}
/*
* Build the new pg_trigger tuple.
*/
@ -329,6 +354,7 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
values[Anum_pg_trigger_tgargs - 1] = DirectFunctionCall1(byteain,
CStringGetDatum(""));
}
/* tgattr is currently always a zero-length array */
tgattr = buildint2vector(NULL, 0);
values[Anum_pg_trigger_tgattr - 1] = PointerGetDatum(tgattr);
@ -430,6 +456,199 @@ CreateTrigger(CreateTrigStmt *stmt, Oid constraintOid)
return trigoid;
}
/*
* Convert legacy (pre-7.3) CREATE CONSTRAINT TRIGGER commands into
* full-fledged foreign key constraints.
*
* The conversion is complex because a pre-7.3 foreign key involved three
* separate triggers, which were reported separately in dumps. While the
* single trigger on the referencing table can be ignored, we need info
* from both of the triggers on the referenced table to build the constraint
* declaration. Our approach is to save info from the first trigger seen
* in a list in TopMemoryContext. When we see the second trigger we can
* create the FK constraint and remove the list entry. We match triggers
* together by comparing the trigger arguments (which include constraint
* name, table and column names, so should be good enough).
*/
typedef struct {
List *args; /* list of (T_String) Values or NIL */
Oid funcoid; /* OID of trigger function */
bool isupd; /* is it the UPDATE trigger? */
} OldTriggerInfo;
static void
ConvertTriggerToFK(CreateTrigStmt *stmt, Oid funcoid)
{
static List *info_list = NIL;
bool isupd;
OldTriggerInfo *info = NULL;
ListCell *l;
/* Identify class of trigger --- update, delete, or referencing-table */
switch (funcoid)
{
case F_RI_FKEY_CASCADE_DEL:
case F_RI_FKEY_RESTRICT_DEL:
case F_RI_FKEY_SETNULL_DEL:
case F_RI_FKEY_SETDEFAULT_DEL:
case F_RI_FKEY_NOACTION_DEL:
isupd = false;
break;
case F_RI_FKEY_CASCADE_UPD:
case F_RI_FKEY_RESTRICT_UPD:
case F_RI_FKEY_SETNULL_UPD:
case F_RI_FKEY_SETDEFAULT_UPD:
case F_RI_FKEY_NOACTION_UPD:
isupd = true;
break;
default:
/* Ignore triggers on referencing table */
ereport(NOTICE,
(errmsg("ignoring incomplete foreign-key trigger group for constraint \"%s\" on table \"%s\"",
stmt->trigname, stmt->relation->relname)));
return;
}
/* See if we have a match to this trigger */
foreach(l, info_list)
{
info = (OldTriggerInfo *) lfirst(l);
if (info->isupd != isupd && equal(info->args, stmt->args))
break;
}
if (l == NULL)
{
/* First trigger of pair, so save away what we need */
MemoryContext oldContext;
ereport(NOTICE,
(errmsg("ignoring incomplete foreign-key trigger group for constraint \"%s\" on table \"%s\"",
stmt->trigname, stmt->constrrel->relname)));
oldContext = MemoryContextSwitchTo(TopMemoryContext);
info = (OldTriggerInfo *) palloc(sizeof(OldTriggerInfo));
info->args = copyObject(stmt->args);
info->funcoid = funcoid;
info->isupd = isupd;
info_list = lappend(info_list, info);
MemoryContextSwitchTo(oldContext);
}
else
{
/* OK, we have a pair, so make the FK constraint */
AlterTableStmt *atstmt = makeNode(AlterTableStmt);
AlterTableCmd *atcmd = makeNode(AlterTableCmd);
FkConstraint *fkcon = makeNode(FkConstraint);
int i;
Oid updfunc,
delfunc;
ereport(NOTICE,
(errmsg("converting foreign-key trigger group into constraint \"%s\" on table \"%s\"",
stmt->trigname, stmt->constrrel->relname)));
atstmt->relation = stmt->constrrel;
atstmt->cmds = list_make1(atcmd);
atstmt->relkind = OBJECT_TABLE;
atcmd->subtype = AT_AddConstraint;
atcmd->def = (Node *) fkcon;
if (strcmp(stmt->trigname, "<unnamed>") == 0)
fkcon->constr_name = NULL;
else
fkcon->constr_name = stmt->trigname;
fkcon->pktable = stmt->relation;
i = 0;
foreach(l, stmt->args)
{
Value *arg = (Value *) lfirst(l);
i++;
if (i < 4) /* ignore constraint and table names */
continue;
if (i == 4) /* handle match type */
{
if (strcmp(strVal(arg), "FULL") == 0)
fkcon->fk_matchtype = FKCONSTR_MATCH_FULL;
else
fkcon->fk_matchtype = FKCONSTR_MATCH_UNSPECIFIED;
continue;
}
if (i % 2)
fkcon->fk_attrs = lappend(fkcon->fk_attrs, arg);
else
fkcon->pk_attrs = lappend(fkcon->pk_attrs, arg);
}
if (isupd)
{
updfunc = funcoid;
delfunc = info->funcoid;
}
else
{
updfunc = info->funcoid;
delfunc = funcoid;
}
switch (updfunc)
{
case F_RI_FKEY_NOACTION_UPD:
fkcon->fk_upd_action = FKCONSTR_ACTION_NOACTION;
break;
case F_RI_FKEY_CASCADE_UPD:
fkcon->fk_upd_action = FKCONSTR_ACTION_CASCADE;
break;
case F_RI_FKEY_RESTRICT_UPD:
fkcon->fk_upd_action = FKCONSTR_ACTION_RESTRICT;
break;
case F_RI_FKEY_SETNULL_UPD:
fkcon->fk_upd_action = FKCONSTR_ACTION_SETNULL;
break;
case F_RI_FKEY_SETDEFAULT_UPD:
fkcon->fk_upd_action = FKCONSTR_ACTION_SETDEFAULT;
break;
default:
/* can't get here because of earlier checks */
elog(ERROR, "confused about RI update function");
}
switch (delfunc)
{
case F_RI_FKEY_NOACTION_DEL:
fkcon->fk_del_action = FKCONSTR_ACTION_NOACTION;
break;
case F_RI_FKEY_CASCADE_DEL:
fkcon->fk_del_action = FKCONSTR_ACTION_CASCADE;
break;
case F_RI_FKEY_RESTRICT_DEL:
fkcon->fk_del_action = FKCONSTR_ACTION_RESTRICT;
break;
case F_RI_FKEY_SETNULL_DEL:
fkcon->fk_del_action = FKCONSTR_ACTION_SETNULL;
break;
case F_RI_FKEY_SETDEFAULT_DEL:
fkcon->fk_del_action = FKCONSTR_ACTION_SETDEFAULT;
break;
default:
/* can't get here because of earlier checks */
elog(ERROR, "confused about RI delete function");
}
fkcon->deferrable = stmt->deferrable;
fkcon->initdeferred = stmt->initdeferred;
ProcessUtility((Node *) atstmt,
NULL, NULL, false, None_Receiver, NULL);
/* Remove the matched item from the list */
info_list = list_delete_ptr(info_list, info);
pfree(info);
/* We leak the copied args ... not worth worrying about */
}
}
/*
* DropTrigger - drop an individual trigger by name
*/

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