WAL-log the creation of the init fork of unlogged indexes.

We create a file, so we better WAL-log it. In practice, all the
built-in index AMs and all extensions that I'm aware of write a
metapage to the init fork, which is WAL-logged, and replay of the
metapage implicitly creates the fork too. But if ambuildempty() didn't
write any page, we would miss it.

This can be seen with dummy_index_am. Set up replication, create a
'dummy_index_am' index on an unlogged table, and look at the files
created in the replica: the init fork is not created on the
replica. Dummy_index_am doesn't do anything with the relation files,
however, so it doesn't lead to any user-visible errors.

Backpatch to all supported versions.

Reviewed-by: Robert Haas
Discussion: https://www.postgresql.org/message-id/6e5bbc08-cdfc-b2b3-9e23-1a914b9850a9%40iki.fi

1 files changed, 2 insertions, 0 deletions

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 352e43d0e61..67b743e2514 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -54,6 +54,7 @@
 #include "catalog/pg_trigger.h"
 #include "catalog/pg_type.h"
 #include "catalog/storage.h"
+#include "catalog/storage_xlog.h"
 #include "commands/event_trigger.h"
 #include "commands/progress.h"
 #include "commands/tablecmds.h"
@@ -3044,6 +3045,7 @@ index_build(Relation heapRelation,
 		!smgrexists(RelationGetSmgr(indexRelation), INIT_FORKNUM))
 	{
 		smgrcreate(RelationGetSmgr(indexRelation), INIT_FORKNUM, false);
+		log_smgrcreate(&indexRelation->rd_locator, INIT_FORKNUM);
 		indexRelation->rd_indam->ambuildempty(indexRelation);
 	}