Preserve replica identity index across ALTER TABLE rewrite

If an index was explicitly set as replica identity index, this setting
was lost when a table was rewritten by ALTER TABLE.  Because this
setting is part of pg_index but actually controlled by ALTER
TABLE (not part of CREATE INDEX, say), we have to do some extra work
to restore it.

Based-on-patch-by: Quan Zongliang <[email protected]>
Reviewed-by: Euler Taveira <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/[email protected]

1 files changed, 23 insertions, 0 deletions

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 6b24369de8f..27bbb58f564 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -3255,6 +3255,29 @@ get_index_column_opclass(Oid index_oid, int attno)
 }
 
 /*
+ * get_index_isreplident
+ *
+ *		Given the index OID, return pg_index.indisreplident.
+ */
+bool
+get_index_isreplident(Oid index_oid)
+{
+	HeapTuple		tuple;
+	Form_pg_index	rd_index;
+	bool			result;
+
+	tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
+	if (!HeapTupleIsValid(tuple))
+		return false;
+
+	rd_index = (Form_pg_index) GETSTRUCT(tuple);
+	result = rd_index->indisreplident;
+	ReleaseSysCache(tuple);
+
+	return result;
+}
+
+/*
  * get_index_isvalid
  *
  *		Given the index OID, return pg_index.indisvalid.