Revert "Skip WAL for new relfilenodes, under wal_level=minimal."

This reverts commit cb2fd7eac285b1b0a24eeb2b8ed4456b66c5a09f.  Per
numerous buildfarm members, it was incompatible with parallel query, and
a test case assumed LP64.  Back-patch to 9.5 (all supported versions).

Discussion: https://postgr.es/m/20200321224920.GB1763544@rfd.leadboat.com

1 files changed, 7 insertions, 22 deletions

diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 0cfb2338aaa..1c90f8c3382 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -747,6 +747,7 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex, bool verbose,
 	bool	   *isnull;
 	IndexScanDesc indexScan;
 	HeapScanDesc heapScan;
+	bool		use_wal;
 	bool		is_system_catalog;
 	TransactionId OldestXmin;
 	TransactionId FreezeXid;
@@ -802,9 +803,12 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex, bool verbose,
 		LockRelationOid(OldHeap->rd_rel->reltoastrelid, AccessExclusiveLock);
 
 	/*
-	 * Valid smgr_targblock implies something already wrote to the relation.
-	 * This may be harmless, but this function hasn't planned for it.
+	 * We need to log the copied data in WAL iff WAL archiving/streaming is
+	 * enabled AND it's a WAL-logged rel.
 	 */
+	use_wal = XLogIsNeeded() && RelationNeedsWAL(NewHeap);
+
+	/* use_wal off requires smgr_targblock be initially invalid */
 	Assert(RelationGetTargetBlock(NewHeap) == InvalidBlockNumber);
 
 	/*
@@ -872,7 +876,7 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex, bool verbose,
 
 	/* Initialize the rewrite operation */
 	rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin, FreezeXid,
-								 MultiXactCutoff);
+								 MultiXactCutoff, use_wal);
 
 	/*
 	 * Decide whether to use an indexscan or seqscan-and-optional-sort to scan
@@ -1243,25 +1247,6 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class,
 	}
 
 	/*
-	 * Recognize that rel1's relfilenode (swapped from rel2) is new in this
-	 * subtransaction. The rel2 storage (swapped from rel1) may or may not be
-	 * new.
-	 */
-	{
-		Relation	rel1,
-					rel2;
-
-		rel1 = relation_open(r1, NoLock);
-		rel2 = relation_open(r2, NoLock);
-		rel2->rd_createSubid = rel1->rd_createSubid;
-		rel2->rd_newRelfilenodeSubid = rel1->rd_newRelfilenodeSubid;
-		rel2->rd_firstRelfilenodeSubid = rel1->rd_firstRelfilenodeSubid;
-		RelationAssumeNewRelfilenode(rel1);
-		relation_close(rel1, NoLock);
-		relation_close(rel2, NoLock);
-	}
-
-	/*
 	 * In the case of a shared catalog, these next few steps will only affect
 	 * our own database's pg_class row; but that's okay, because they are all
 	 * noncritical updates.  That's also an important fact for the case of a