Fix parallel restore of FKs to partitioned tables

When an FK constraint is created, it needs the index on the referenced
table to exist and be valid.  When doing parallel pg_restore and the
referenced table was partitioned, this condition can sometimes not be
met, because pg_dump didn't emit sufficient object dependencies to
ensure so; this means that parallel pg_restore would fail in certain
conditions.  Fix by having pg_dump make the FK constraint object
dependent on the partition attachment objects for the constraint's
referenced index.

This has been broken since f56f8f8, so backpatch to Postgres 12.

Discussion: https://postgr.es/m/20191005224333.GA9738@alvherre.pgsql

Author: alvherre

src/bin/pg_dump/common.c

@@ -412,6 +412,9 @@ flagInhIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 			addObjectDependency(&attachinfo[k].dobj,
 								parentidx->indextable->dobj.dumpId);
 
+			/* keep track of the list of partitions in the parent index */
+			simple_ptr_list_append(&parentidx->partattaches, &attachinfo[k].dobj);
+
 			k++;
 		}
 	}

src/bin/pg_dump/pg_dump.c

@@ -7115,6 +7115,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 			indxinfo[j].indisclustered = (PQgetvalue(res, j, i_indisclustered)[0] == 't');
 			indxinfo[j].indisreplident = (PQgetvalue(res, j, i_indisreplident)[0] == 't');
 			indxinfo[j].parentidx = atooid(PQgetvalue(res, j, i_parentidx));
+			indxinfo[j].partattaches = (SimplePtrList) { NULL, NULL };
 			contype = *(PQgetvalue(res, j, i_contype));
 
 			if (contype == 'p' || contype == 'u' || contype == 'x')
@@ -7256,6 +7257,7 @@ getConstraints(Archive *fout, TableInfo tblinfo[], int numTables)
 				i_conoid,
 				i_conname,
 				i_confrelid,
+				i_conindid,
 				i_condef;
 	int			ntups;
 
@@ -7281,7 +7283,7 @@ getConstraints(Archive *fout, TableInfo tblinfo[], int numTables)
 		resetPQExpBuffer(query);
 		if (fout->remoteVersion >= 110000)
 			appendPQExpBuffer(query,
-							  "SELECT tableoid, oid, conname, confrelid, "
+							  "SELECT tableoid, oid, conname, confrelid, conindid, "
 							  "pg_catalog.pg_get_constraintdef(oid) AS condef "
 							  "FROM pg_catalog.pg_constraint "
 							  "WHERE conrelid = '%u'::pg_catalog.oid "
@@ -7290,7 +7292,7 @@ getConstraints(Archive *fout, TableInfo tblinfo[], int numTables)
 							  tbinfo->dobj.catId.oid);
 		else
 			appendPQExpBuffer(query,
-							  "SELECT tableoid, oid, conname, confrelid, "
+							  "SELECT tableoid, oid, conname, confrelid, 0 as conindid, "
 							  "pg_catalog.pg_get_constraintdef(oid) AS condef "
 							  "FROM pg_catalog.pg_constraint "
 							  "WHERE conrelid = '%u'::pg_catalog.oid "
@@ -7304,12 +7306,15 @@ getConstraints(Archive *fout, TableInfo tblinfo[], int numTables)
 		i_conoid = PQfnumber(res, "oid");
 		i_conname = PQfnumber(res, "conname");
 		i_confrelid = PQfnumber(res, "confrelid");
+		i_conindid = PQfnumber(res, "conindid");
 		i_condef = PQfnumber(res, "condef");
 
 		constrinfo = (ConstraintInfo *) pg_malloc(ntups * sizeof(ConstraintInfo));
 
 		for (j = 0; j < ntups; j++)
 		{
+			TableInfo *reftable;
+
 			constrinfo[j].dobj.objType = DO_FK_CONSTRAINT;
 			constrinfo[j].dobj.catId.tableoid = atooid(PQgetvalue(res, j, i_contableoid));
 			constrinfo[j].dobj.catId.oid = atooid(PQgetvalue(res, j, i_conoid));
@@ -7326,6 +7331,39 @@ getConstraints(Archive *fout, TableInfo tblinfo[], int numTables)
 			constrinfo[j].condeferred = false;
 			constrinfo[j].conislocal = true;
 			constrinfo[j].separate = true;
+
+			/*
+			 * Restoring an FK that points to a partitioned table requires
+			 * that all partition indexes have been attached beforehand.
+			 * Ensure that happens by making the constraint depend on each
+			 * index partition attach object.
+			 */
+			reftable = findTableByOid(constrinfo[j].confrelid);
+			if (reftable && reftable->relkind == RELKIND_PARTITIONED_TABLE)
+			{
+				IndxInfo   *refidx;
+				Oid			indexOid = atooid(PQgetvalue(res, j, i_conindid));
+
+				if (indexOid != InvalidOid)
+				{
+					for (int k = 0; k < reftable->numIndexes; k++)
+					{
+						SimplePtrListCell *cell;
+
+						/* not our index? */
+						if (reftable->indexes[k].dobj.catId.oid != indexOid)
+							continue;
+
+						refidx = &reftable->indexes[k];
+						for (cell = refidx->partattaches.head; cell;
+							 cell = cell->next)
+							addObjectDependency(&constrinfo[j].dobj,
+												((DumpableObject *)
+												 cell->ptr)->dumpId);
+						break;
+					}
+				}
+			}
 		}
 
 		PQclear(res);

src/bin/pg_dump/pg_dump.h

@@ -367,6 +367,8 @@ typedef struct _indxInfo
 	bool		indisclustered;
 	bool		indisreplident;
 	Oid			parentidx;		/* if partitioned, parent index OID */
+	SimplePtrList partattaches;	/* if partitioned, partition attach objects */
+
 	/* if there is an associated constraint object, its dumpId: */
 	DumpId		indexconstraint;
 } IndxInfo;

src/fe_utils/simple_list.c

@@ -152,3 +152,24 @@ simple_string_list_not_touched(SimpleStringList *list)
 	}
 	return NULL;
 }
+
+/*
+ * Append a pointer to the list.
+ *
+ * Caller must ensure that the pointer remains valid.
+ */
+void
+simple_ptr_list_append(SimplePtrList *list, void *ptr)
+{
+	SimplePtrListCell *cell;
+
+	cell = (SimplePtrListCell *) pg_malloc(sizeof(SimplePtrListCell));
+	cell->next = NULL;
+	cell->ptr = ptr;
+
+	if (list->tail)
+		list->tail->next = cell;
+	else
+		list->head = cell;
+	list->tail = cell;
+}

src/include/fe_utils/simple_list.h

@@ -2,9 +2,9 @@
  *
  * Simple list facilities for frontend code
  *
- * Data structures for simple lists of OIDs and strings.  The support for
- * these is very primitive compared to the backend's List facilities, but
- * it's all we need in, eg, pg_dump.
+ * Data structures for simple lists of OIDs, strings, and pointers.  The
+ * support for these is very primitive compared to the backend's List
+ * facilities, but it's all we need in, eg, pg_dump.
  *
  *
  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
@@ -43,6 +43,17 @@ typedef struct SimpleStringList
 	SimpleStringListCell *tail;
 } SimpleStringList;
 
+typedef struct SimplePtrListCell
+{
+	struct SimplePtrListCell *next;
+	void	   *ptr;
+} SimplePtrListCell;
+
+typedef struct SimplePtrList
+{
+	SimplePtrListCell *head;
+	SimplePtrListCell *tail;
+} SimplePtrList;
 
 extern void simple_oid_list_append(SimpleOidList *list, Oid val);
 extern bool simple_oid_list_member(SimpleOidList *list, Oid val);
@@ -54,4 +65,6 @@ extern void simple_string_list_destroy(SimpleStringList *list);
 
 extern const char *simple_string_list_not_touched(SimpleStringList *list);
 
+extern void simple_ptr_list_append(SimplePtrList *list, void *val);
+
 #endif							/* SIMPLE_LIST_H */