Fix identify_locking_dependencies for schema-only dumps.

robertmhaas · robertmhaas · commit bbe3c069a248 · 2014-09-26T11:43:56.000-04:00
Without this fix, parallel restore of a schema-only dump can deadlock,
because when the dump is schema-only, the dependency will still be
pointing at the TABLE item rather than the TABLE DATA item.

Robert Haas and Tom Lane
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
@@ -4085,11 +4085,14 @@ identify_locking_dependencies(TocEntry *te)
 		return;
 
 	/*
-	 * We assume the item requires exclusive lock on each TABLE DATA item
-	 * listed among its dependencies.  (This was originally a dependency on
-	 * the TABLE, but fix_dependencies repointed it to the data item. Note
-	 * that all the entry types we are interested in here are POST_DATA, so
-	 * they will all have been changed this way.)
+	 * We assume the entry requires exclusive lock on each TABLE or TABLE DATA
+	 * item listed among its dependencies.  Originally all of these would have
+	 * been TABLE items, but repoint_table_dependencies would have repointed
+	 * them to the TABLE DATA items if those are present (which they might not
+	 * be, eg in a schema-only dump).  Note that all of the entries we are
+	 * processing here are POST_DATA; otherwise there might be a significant
+	 * difference between a dependency on a table and a dependency on its
+	 * data, so that closer analysis would be needed here.
 	 */
 	lockids = (DumpId *) malloc(te->nDeps * sizeof(DumpId));
 	nlockids = 0;
@@ -4098,7 +4101,8 @@ identify_locking_dependencies(TocEntry *te)
 		DumpId		depid = te->dependencies[i];
 
 		if (depid <= maxDumpId && tocsByDumpId[depid - 1] &&
-			strcmp(tocsByDumpId[depid - 1]->desc, "TABLE DATA") == 0)
+			((strcmp(tocsByDumpId[depid - 1]->desc, "TABLE DATA") == 0) ||
+			  strcmp(tocsByDumpId[depid - 1]->desc, "TABLE") == 0))
 			lockids[nlockids++] = depid;
 	}
 
