branches/zip: row_merge_drop_temp_indexes(): Do not lock the rows of

SYS_INDEXES when looking for partially created indexes.  Use the
transaction isolation level READ UNCOMMITTED to avoid interfering with
locks held by incomplete transactions that will be rolled back in a
subsequent step in the recovery.  (Issue #152)

Approved by Heikki Tuuri

row/row0merge.c

@@ -1833,7 +1833,7 @@ row_merge_drop_temp_indexes(void)
 		"PROCEDURE DROP_TEMP_INDEXES_PROC () IS\n"
 		"indexid CHAR;\n"
 		"DECLARE CURSOR c IS SELECT ID FROM SYS_INDEXES\n"
-		"WHERE SUBSTR(NAME,0,1)='\377' FOR UPDATE;\n"
+		"WHERE SUBSTR(NAME,0,1)='\377';\n"
 		"BEGIN\n"
 		"\tOPEN c;\n"
 		"\tWHILE 1=1 LOOP\n"
@@ -1842,7 +1842,7 @@ row_merge_drop_temp_indexes(void)
 		"\t\t\tEXIT;\n"
 		"\t\tEND IF;\n"
 		"\t\tDELETE FROM SYS_FIELDS WHERE INDEX_ID = indexid;\n"
-		"\t\tDELETE FROM SYS_INDEXES WHERE CURRENT OF c;\n"
+		"\t\tDELETE FROM SYS_INDEXES WHERE ID = indexid;\n"
 		"\tEND LOOP;\n"
 		"\tCLOSE c;\n"
 		"\tCOMMIT WORK;\n"
@@ -1852,6 +1852,15 @@ row_merge_drop_temp_indexes(void)
 	trx->op_info = "dropping partially created indexes";
 	row_mysql_lock_data_dictionary(trx);
 
+	/* Incomplete transactions may be holding some locks on the
+	data dictionary tables.  However, they should never have been
+	able to lock the records corresponding to the partially
+	created indexes that we are attempting to delete, because the
+	table was locked when the indexes were being created.  We will
+	drop the partially created indexes before the rollback of
+	incomplete transactions is initiated.  Thus, this should not
+	interfere with the incomplete transactions. */
+	trx->isolation_level = TRX_ISO_READ_UNCOMMITTED;
 	err = que_eval_sql(NULL, drop_temp_indexes, FALSE, trx);
 	ut_a(err == DB_SUCCESS);