From 1ffa59a85cb40a61f4523fb03c8960db97eea124 Mon Sep 17 00:00:00 2001 From: Peter Eisentraut Date: Mon, 18 Mar 2019 17:01:40 +0100 Subject: Fix optimization of foreign-key on update actions In RI_FKey_pk_upd_check_required(), we check among other things whether the old and new key are equal, so that we don't need to run cascade actions when nothing has actually changed. This was using the equality operator. But the effect of this is that if a value in the primary key is changed to one that "looks" different but compares as equal, the update is not propagated. (Examples are float -0 and 0 and case-insensitive text.) This appears to violate the SQL standard, and it also behaves inconsistently if in a multicolumn key another key is also updated that would cause the row to compare as not equal. To fix, if we are looking at the PK table in ri_KeysEqual(), then do a bytewise comparison similar to record_image_eq() instead of using the equality operators. This only makes a difference for ON UPDATE CASCADE, but for consistency we treat all changes to the PK the same. For the FK table, we continue to use the equality operators. Discussion: https://www.postgresql.org/message-id/flat/3326fc2e-bc02-d4c5-e3e5-e54da466e89a@2ndquadrant.com --- src/backend/utils/adt/ri_triggers.c | 40 +++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 13 deletions(-) (limited to 'src/backend/utils/adt/ri_triggers.c') diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c index d715709b7cd..b4d0029877b 100644 --- a/src/backend/utils/adt/ri_triggers.c +++ b/src/backend/utils/adt/ri_triggers.c @@ -42,6 +42,7 @@ #include "storage/bufmgr.h" #include "utils/acl.h" #include "utils/builtins.h" +#include "utils/datum.h" #include "utils/fmgroids.h" #include "utils/guc.h" #include "utils/inval.h" @@ -2402,18 +2403,11 @@ ri_KeysEqual(Relation rel, TupleTableSlot *oldslot, TupleTableSlot *newslot, const RI_ConstraintInfo *riinfo, bool rel_is_pk) { const int16 *attnums; - const Oid *eq_oprs; if (rel_is_pk) - { attnums = riinfo->pk_attnums; - eq_oprs = riinfo->pp_eq_oprs; - } else - { attnums = riinfo->fk_attnums; - eq_oprs = riinfo->ff_eq_oprs; - } /* XXX: could be worthwhile to fetch all necessary attrs at once */ for (int i = 0; i < riinfo->nkeys; i++) @@ -2436,12 +2430,32 @@ ri_KeysEqual(Relation rel, TupleTableSlot *oldslot, TupleTableSlot *newslot, if (isnull) return false; - /* - * Compare them with the appropriate equality operator. - */ - if (!ri_AttributesEqual(eq_oprs[i], RIAttType(rel, attnums[i]), - oldvalue, newvalue)) - return false; + if (rel_is_pk) + { + /* + * If we are looking at the PK table, then do a bytewise + * comparison. We must propagate PK changes if the value is + * changed to one that "looks" different but would compare as + * equal using the equality operator. This only makes a + * difference for ON UPDATE CASCADE, but for consistency we treat + * all changes to the PK the same. + */ + Form_pg_attribute att = TupleDescAttr(oldslot->tts_tupleDescriptor, attnums[i] - 1); + + if (!datum_image_eq(oldvalue, newvalue, att->attbyval, att->attlen)) + return false; + } + else + { + /* + * For the FK table, compare with the appropriate equality + * operator. Changes that compare equal will still satisfy the + * constraint after the update. + */ + if (!ri_AttributesEqual(riinfo->ff_eq_oprs[i], RIAttType(rel, attnums[i]), + oldvalue, newvalue)) + return false; + } } return true; -- cgit v1.2.3