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

3 files changed, 6 insertions, 47 deletions

diff --git a/src/backend/access/gist/gistbuild.c b/src/backend/access/gist/gistbuild.c
index 0444e3a1072..ff888e2e01d 100644
--- a/src/backend/access/gist/gistbuild.c
+++ b/src/backend/access/gist/gistbuild.c
@@ -191,7 +191,7 @@ gistbuild(PG_FUNCTION_ARGS)
 		PageSetLSN(page, recptr);
 	}
 	else
-		PageSetLSN(page, gistGetFakeLSN(index));
+		PageSetLSN(page, gistGetFakeLSN(heap));
 
 	UnlockReleaseBuffer(buffer);
 
diff --git a/src/backend/access/gist/gistutil.c b/src/backend/access/gist/gistutil.c
index 47cb7fde518..7d596a3e2e6 100644
--- a/src/backend/access/gist/gistutil.c
+++ b/src/backend/access/gist/gistutil.c
@@ -840,44 +840,23 @@ gistoptions(PG_FUNCTION_ARGS)
 }
 
 /*
- * Some indexes are not WAL-logged, but we need LSNs to detect concurrent page
- * splits anyway. This function provides a fake sequence of LSNs for that
- * purpose.
+ * Temporary and unlogged GiST indexes are not WAL-logged, but we need LSNs
+ * to detect concurrent page splits anyway. This function provides a fake
+ * sequence of LSNs for that purpose.
  */
 XLogRecPtr
 gistGetFakeLSN(Relation rel)
 {
+	static XLogRecPtr counter = 1;
+
 	if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
 	{
 		/*
 		 * Temporary relations are only accessible in our session, so a simple
 		 * backend-local counter will do.
 		 */
-		static XLogRecPtr counter = 1;
-
 		return counter++;
 	}
-	else if (rel->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
-	{
-		/*
-		 * WAL-logging on this relation will start after commit, so its LSNs
-		 * must be distinct numbers smaller than the LSN at the next commit.
-		 * Emit a dummy WAL record if insert-LSN hasn't advanced after the
-		 * last call.
-		 */
-		static XLogRecPtr lastlsn = InvalidXLogRecPtr;
-		XLogRecPtr	currlsn = GetXLogInsertRecPtr();
-
-		/* Shouldn't be called for WAL-logging relations */
-		Assert(!RelationNeedsWAL(rel));
-
-		/* No need for an actual record if we already have a distinct LSN */
-		if (!XLogRecPtrIsInvalid(lastlsn) && lastlsn == currlsn)
-			currlsn = gistXLogAssignLSN();
-
-		lastlsn = currlsn;
-		return currlsn;
-	}
 	else
 	{
 		/*
diff --git a/src/backend/access/gist/gistxlog.c b/src/backend/access/gist/gistxlog.c
index e002ad3d829..fbdbb3c51f2 100644
--- a/src/backend/access/gist/gistxlog.c
+++ b/src/backend/access/gist/gistxlog.c
@@ -301,9 +301,6 @@ gist_redo(XLogReaderState *record)
 		case XLOG_GIST_CREATE_INDEX:
 			gistRedoCreateIndex(record);
 			break;
-		case XLOG_GIST_ASSIGN_LSN:
-			/* nop. See gistGetFakeLSN(). */
-			break;
 		default:
 			elog(PANIC, "gist_redo: unknown op code %u", info);
 	}
@@ -381,23 +378,6 @@ gistXLogSplit(RelFileNode node, BlockNumber blkno, bool page_is_leaf,
 }
 
 /*
- * Write an empty XLOG record to assign a distinct LSN.
- */
-XLogRecPtr
-gistXLogAssignLSN(void)
-{
-	int			dummy = 0;
-
-	/*
-	 * Records other than SWITCH_WAL must have content. We use an integer 0 to
-	 * follow the restriction.
-	 */
-	XLogBeginInsert();
-	XLogRegisterData((char *) &dummy, sizeof(dummy));
-	return XLogInsert(RM_GIST_ID, XLOG_GIST_ASSIGN_LSN);
-}
-
-/*
  * Write XLOG record describing a page update. The update can include any
  * number of deletions and/or insertions of tuples on a single index page.
  *