Revert "pg_dump: Lock all relations, not just plain tables".

tglsfdc · tglsfdc · commit 768ab4d676aa · 2020-11-06T15:48:21.000-05:00
Revert 403a3d9, as well as the followup fix 7f42350, in all branches. We need to think a bit harder about what the behavior of LOCK TABLE on views should be, and there's no time for that before next week's releases. We'll take another crack at this later. Discussion: https://postgr.es/m/16703-e348f58aab3cf6cc@postgresql.org
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
@@ -188,8 +188,6 @@ typedef struct Archive
 	int			minRemoteVersion;		/* allowable range */
 	int			maxRemoteVersion;
 
-	bool		hasGenericLockTable;	/* can LOCK TABLE do non-table rels */
-
 	int			numWorkers;		/* number of parallel processes */
 	char	   *sync_snapshot_id;		/* sync snapshot id for parallel
 										 * operation */
diff --git a/src/bin/pg_dump/pg_backup_db.c b/src/bin/pg_dump/pg_backup_db.c
@@ -552,73 +552,6 @@ EndDBCopyMode(Archive *AHX, const char *tocEntryTag)
 	}
 }
 
-/*
- * Does LOCK TABLE work on non-table relations on this server?
- *
- * Note: assumes it is called out of any transaction
- */
-bool
-IsLockTableGeneric(Archive *AHX)
-{
-	ArchiveHandle *AH = (ArchiveHandle *) AHX;
-	PGresult   *res;
-	char	   *sqlstate;
-	bool		retval;
-
-	if (AHX->remoteVersion >= 140000)
-		return true;
-	else if (AHX->remoteVersion < 90500)
-		return false;
-
-	StartTransaction(AHX);
-
-	/*
-	 * Try a LOCK TABLE on a well-known non-table catalog; WRONG_OBJECT_TYPE
-	 * tells us that this server doesn't support locking non-table rels, while
-	 * LOCK_NOT_AVAILABLE and INSUFFICIENT_PRIVILEGE tell us that it does.
-	 * Report anything else as a fatal problem.
-	 */
-#define ERRCODE_INSUFFICIENT_PRIVILEGE	"42501"
-#define ERRCODE_WRONG_OBJECT_TYPE	"42809"
-#define ERRCODE_LOCK_NOT_AVAILABLE	"55P03"
-	res = PQexec(AH->connection,
-				 "LOCK TABLE pg_catalog.pg_class_tblspc_relfilenode_index IN ACCESS SHARE MODE NOWAIT");
-	switch (PQresultStatus(res))
-	{
-		case PGRES_COMMAND_OK:
-			retval = true;
-			break;
-		case PGRES_FATAL_ERROR:
-			sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
-			if (sqlstate &&
-				strcmp(sqlstate, ERRCODE_WRONG_OBJECT_TYPE) == 0)
-			{
-				retval = false;
-				break;
-			}
-			else if (sqlstate &&
-					 (strcmp(sqlstate, ERRCODE_LOCK_NOT_AVAILABLE) == 0 ||
-					  strcmp(sqlstate, ERRCODE_INSUFFICIENT_PRIVILEGE) == 0))
-			{
-				retval = true;
-				break;
-			}
-			/* else, falls through */
-		default:
-			warn_or_exit_horribly(AH, modulename,
-								  "LOCK TABLE failed for \"%s\": %s",
-								  "pg_catalog.pg_class_tblspc_relfilenode_index",
-								  PQerrorMessage(AH->connection));
-			retval = false;		/* not reached */
-			break;
-	}
-	PQclear(res);
-
-	CommitTransaction(AHX);
-
-	return retval;
-}
-
 void
 StartTransaction(Archive *AHX)
 {
diff --git a/src/bin/pg_dump/pg_backup_db.h b/src/bin/pg_dump/pg_backup_db.h
@@ -20,8 +20,6 @@ extern PGresult *ExecuteSqlQueryForSingleRow(Archive *fout, char *query);
 
 extern void EndDBCopyMode(Archive *AHX, const char *tocEntryTag);
 
-extern bool IsLockTableGeneric(Archive *AHX);
-
 extern void StartTransaction(Archive *AHX);
 extern void CommitTransaction(Archive *AHX);
 
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
@@ -1081,9 +1081,6 @@ setup_connection(Archive *AH, const char *dumpencoding,
 			ExecuteSqlStatement(AH, "SET row_security = off");
 	}
 
-	/* Detect whether LOCK TABLE can handle non-table relations */
-	AH->hasGenericLockTable = IsLockTableGeneric(AH);
-
 	/*
 	 * Start transaction-snapshot mode transaction to dump consistent data.
 	 */
@@ -6200,15 +6197,13 @@ getTables(Archive *fout, int *numTables)
 		 * assume our lock on the child is enough to prevent schema
 		 * alterations to parent tables.
 		 *
-		 * We only need to lock the relation for certain components; see
-		 * pg_dump.h
+		 * NOTE: it'd be kinda nice to lock other relations too, not only
+		 * plain tables, but the backend doesn't presently allow that.
 		 *
-		 * On server versions that support it, we lock all relations not just
-		 * plain tables.
+		 * We only need to lock the table for certain components; see
+		 * pg_dump.h
 		 */
-		if (tblinfo[i].dobj.dump &&
-			(fout->hasGenericLockTable ||
-			 tblinfo[i].relkind == RELKIND_RELATION) &&
+		if (tblinfo[i].dobj.dump && tblinfo[i].relkind == RELKIND_RELATION &&
 			(tblinfo[i].dobj.dump & DUMP_COMPONENTS_REQUIRING_LOCK))
 		{
 			resetPQExpBuffer(query);
