array-fk-lateral-poc.patch

commit 11eef04f83d6995c9e64654f99f0154f6f422348
Author: Andreas Karlsson <andreas@proxel.se>
Date:   Sun Oct 29 01:35:34 2017 +0200

    PoC

diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index ed11c7a265..166d6c6970 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -2392,15 +2392,7 @@ RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
 	{
 		quoteOneName(fkattname,
 					 RIAttName(fk_rel, riinfo->fk_attnums[i]));
-		if (riinfo->has_array)
-			if (riinfo->fk_reftypes[i] == FKCONSTR_REF_EACH_ELEMENT)
-				appendStringInfo(&querybuf, "%sfk.ak%d %s", sep, i + 1,
-								 fkattname);
-			else
-				appendStringInfo(&querybuf, "%sfk.k%d %s", sep, i + 1,
-								 fkattname);
-		else
-			appendStringInfo(&querybuf, "%sfk.%s", sep, fkattname);
+		appendStringInfo(&querybuf, "%sfk.%s", sep, fkattname);
 		sep = ", ";
 	}
 
@@ -2409,24 +2401,21 @@ RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
 
 	if (riinfo->has_array)
 	{
-		sep = "";
-		appendStringInfo(&querybuf,
-						 " FROM (SELECT ");
+		appendStringInfo(&querybuf, " FROM ONLY %s fk", fkrelname);
 		for (i = 0; i < riinfo->nkeys; i++)
 		{
+			if (riinfo->fk_reftypes[i] != FKCONSTR_REF_EACH_ELEMENT)
+				continue;
+
 			quoteOneName(fkattname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
-			if (riinfo->fk_reftypes[i] == FKCONSTR_REF_EACH_ELEMENT)
-				appendStringInfo(&querybuf, "%spg_catalog.unnest(%s) k%d, %s ak%d",
-								 sep, fkattname, i + 1, fkattname, i + 1);
-			else
-				appendStringInfo(&querybuf, "%s%s k%d", sep, fkattname,
-								 i + 1);
-			sep = ", ";
+			appendStringInfo(&querybuf,
+							 " CROSS JOIN LATERAL pg_catalog.unnest(fk.%s) a (e)",
+							 fkattname);
 		}
 		appendStringInfo(&querybuf,
-						 " FROM ONLY %s) fk LEFT OUTER JOIN ONLY %s pk ON",
-						 fkrelname, pkrelname);
+						 " LEFT OUTER JOIN ONLY %s pk ON",
+						 pkrelname);
 	}
 	else
 		appendStringInfo(&querybuf,
@@ -2442,18 +2431,22 @@ RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
 		Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
 		Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
 		Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
+		char	   *tmp;
 
 		quoteOneName(pkattname + 3,
 					 RIAttName(pk_rel, riinfo->pk_attnums[i]));
-		if (riinfo->has_array)
-			sprintf(fkattname + 3, "k%d", i + 1);
+		if (riinfo->fk_reftypes[i] == FKCONSTR_REF_EACH_ELEMENT)
+			tmp = "a.e";
 		else
+		{
 			quoteOneName(fkattname + 3,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
+			tmp = fkattname;
+		}
 		ri_GenerateQual(&querybuf, sep,
 						pkattname, pk_type,
 						riinfo->pf_eq_oprs[i],
-						fkattname, fk_type,
+						tmp, fk_type,
 						FKCONSTR_REF_PLAIN);
 		if (pk_coll != fk_coll)
 			ri_GenerateQualCollation(&querybuf, pk_coll);
@@ -2470,13 +2463,15 @@ RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
 	sep = "";
 	for (i = 0; i < riinfo->nkeys; i++)
 	{
-		if (riinfo->has_array)
-			sprintf(fkattname, "k%d", i + 1);
+		if (riinfo->fk_reftypes[i] == FKCONSTR_REF_EACH_ELEMENT)
+			appendStringInfo(&querybuf, "%sa.e IS NOT NULL", sep);
 		else
+		{
 			quoteOneName(fkattname, RIAttName(fk_rel, riinfo->fk_attnums[i]));
-		appendStringInfo(&querybuf,
-						 "%sfk.%s IS NOT NULL",
-						 sep, fkattname);
+			appendStringInfo(&querybuf,
+							 "%sfk.%s IS NOT NULL",
+							 sep, fkattname);
+		}
 		switch (riinfo->confmatchtype)
 		{
 			case FKCONSTR_MATCH_SIMPLE: