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Commit1e3b21d

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Change FK trigger naming convention to fix self-referential FKs.
Use names like "RI_ConstraintTrigger_a_NNNN" for FK action triggers and"RI_ConstraintTrigger_c_NNNN" for FK check triggers. This ensures theaction trigger fires first in self-referential cases where the very samerow update fires both an action and a check trigger. This change providesa non-probabilistic solution for bug #6268, at the risk that it could breakclient code that is making assumptions about the exact names assigned toauto-generated FK triggers. Hence, change this in HEAD only. No need forforced initdb since old triggers continue to work fine.
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‎src/backend/commands/tablecmds.c

Lines changed: 12 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -6467,8 +6467,17 @@ CreateFKCheckTrigger(RangeVar *myRel, Constraint *fkconstraint,
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{
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CreateTrigStmt*fk_trigger;
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6470+
/*
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* Note: for a self-referential FK (referencing and referenced tables are
6472+
* the same), it is important that the ON UPDATE action fires before the
6473+
* CHECK action, since both triggers will fire on the same row during an
6474+
* UPDATE event; otherwise the CHECK trigger will be checking a non-final
6475+
* state of the row. Triggers fire in name order, so we ensure this by
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* using names like "RI_ConstraintTrigger_a_NNNN" for the action triggers
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* and "RI_ConstraintTrigger_c_NNNN" for the check triggers.
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*/
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fk_trigger=makeNode(CreateTrigStmt);
6471-
fk_trigger->trigname="RI_ConstraintTrigger";
6480+
fk_trigger->trigname="RI_ConstraintTrigger_c";
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fk_trigger->relation=myRel;
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fk_trigger->row= true;
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fk_trigger->timing=TRIGGER_TYPE_AFTER;
@@ -6524,7 +6533,7 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
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* DELETE action on the referenced table.
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*/
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fk_trigger=makeNode(CreateTrigStmt);
6527-
fk_trigger->trigname="RI_ConstraintTrigger";
6536+
fk_trigger->trigname="RI_ConstraintTrigger_a";
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fk_trigger->relation=fkconstraint->pktable;
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fk_trigger->row= true;
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fk_trigger->timing=TRIGGER_TYPE_AFTER;
@@ -6577,7 +6586,7 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
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* UPDATE action on the referenced table.
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*/
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fk_trigger=makeNode(CreateTrigStmt);
6580-
fk_trigger->trigname="RI_ConstraintTrigger";
6589+
fk_trigger->trigname="RI_ConstraintTrigger_a";
65816590
fk_trigger->relation=fkconstraint->pktable;
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fk_trigger->row= true;
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fk_trigger->timing=TRIGGER_TYPE_AFTER;
@@ -6628,17 +6637,6 @@ createForeignKeyTriggers(Relation rel, Constraint *fkconstraint,
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/*
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* Build and execute CREATE CONSTRAINT TRIGGER statements for the CHECK
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* action for both INSERTs and UPDATEs on the referencing table.
6631-
*
6632-
* Note: for a self-referential FK (referencing and referenced tables are
6633-
* the same), it is important that the ON UPDATE action fires before the
6634-
* CHECK action, since both triggers will fire on the same row during an
6635-
* UPDATE event; otherwise the CHECK trigger will be checking a non-final
6636-
* state of the row. Because triggers fire in name order, we are
6637-
* effectively relying on the OIDs of the triggers to sort correctly as
6638-
* text. This will work except when the OID counter wraps around or adds
6639-
* a digit, eg "99999" sorts after "100000". That is infrequent enough,
6640-
* and the use of self-referential FKs is rare enough, that we live with
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* it for now. There will be a real fix in PG 9.2.
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*/
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CreateFKCheckTrigger(myRel,fkconstraint,constraintOid,indexOid, true);
66446642
CreateFKCheckTrigger(myRel,fkconstraint,constraintOid,indexOid, false);

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