Provide database object names as separate fields in error messages.

This patch addresses the problem that applications currently have to
extract object names from possibly-localized textual error messages,
if they want to know for example which index caused a UNIQUE_VIOLATION
failure.  It adds new error message fields to the wire protocol, which
can carry the name of a table, table column, data type, or constraint
associated with the error.  (Since the protocol spec has always instructed
clients to ignore unrecognized field types, this should not create any
compatibility problem.)

Support for providing these new fields has been added to just a limited set
of error reports (mainly, those in the "integrity constraint violation"
SQLSTATE class), but we will doubtless add them to more calls in future.

Pavel Stehule, reviewed and extensively revised by Peter Geoghegan, with
additional hacking by Tom Lane.

1 files changed, 11 insertions, 5 deletions

diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index 243bdebbd22..43228447ea4 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -337,9 +337,11 @@ RI_FKey_check(TriggerData *trigdata)
 					ereport(ERROR,
 							(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
 							 errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
-							  RelationGetRelationName(trigdata->tg_relation),
+									RelationGetRelationName(fk_rel),
 									NameStr(riinfo->conname)),
-							 errdetail("MATCH FULL does not allow mixing of null and nonnull key values.")));
+							 errdetail("MATCH FULL does not allow mixing of null and nonnull key values."),
+							 errtableconstraint(fk_rel,
+												NameStr(riinfo->conname))));
 					heap_close(pk_rel, RowShareLock);
 					return PointerGetDatum(NULL);
 
@@ -2470,7 +2472,9 @@ RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
 					 errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
 							RelationGetRelationName(fk_rel),
 							NameStr(fake_riinfo.conname)),
-					 errdetail("MATCH FULL does not allow mixing of null and nonnull key values.")));
+					 errdetail("MATCH FULL does not allow mixing of null and nonnull key values."),
+					 errtableconstraint(fk_rel,
+										NameStr(fake_riinfo.conname))));
 
 		/*
 		 * We tell ri_ReportViolation we were doing the RI_PLAN_CHECK_LOOKUPPK
@@ -3222,7 +3226,8 @@ ri_ReportViolation(const RI_ConstraintInfo *riinfo,
 						NameStr(riinfo->conname)),
 				 errdetail("Key (%s)=(%s) is not present in table \"%s\".",
 						   key_names.data, key_values.data,
-						   RelationGetRelationName(pk_rel))));
+						   RelationGetRelationName(pk_rel)),
+				 errtableconstraint(fk_rel, NameStr(riinfo->conname))));
 	else
 		ereport(ERROR,
 				(errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
@@ -3232,7 +3237,8 @@ ri_ReportViolation(const RI_ConstraintInfo *riinfo,
 						RelationGetRelationName(fk_rel)),
 			errdetail("Key (%s)=(%s) is still referenced from table \"%s\".",
 					  key_names.data, key_values.data,
-					  RelationGetRelationName(fk_rel))));
+					  RelationGetRelationName(fk_rel)),
+				 errtableconstraint(fk_rel, NameStr(riinfo->conname))));
 }