Issue #437: Cleanup temporary indexes on error (with --only-indexes)

When using --only-indexes pg_repack uses different approach to repack
indexes, which is running CREATE INDEX CONCURRENTLY command to create a
temporary index and swapping the target index and the temporary index
afterwards.
That approach didn't use any cleanup callbacks and therefore in case of
an error temporary indexes wouldn't be cleaned up.

The commit adds the callback repack_cleanup_index.

bin/pg_repack.c

@@ -222,6 +222,7 @@ static bool repack_table_indexes(PGresult *index_details);
 static bool repack_all_indexes(char *errbuf, size_t errsize);
 static void repack_cleanup(bool fatal, const repack_table *table);
 static void repack_cleanup_callback(bool fatal, void *userdata);
+static void repack_cleanup_index(bool fatal, void *userdata);
 static bool rebuild_indexes(const repack_table *table);
 
 static char *getstr(PGresult *res, int row, int col);
@@ -2078,6 +2079,39 @@ repack_cleanup(bool fatal, const repack_table *table)
 	}
 }
 
+/*
+ * Cleanup temporary objects, created during index repacking (with option
+ * --index-only), on error.
+ */
+static void
+repack_cleanup_index(bool fatal, void *userdata)
+{
+	StringInfoData sql, sql_drop;
+	PGresult   *index_details = (PGresult *) userdata;
+	char	   *schema_name;
+	int			num;
+
+	schema_name = getstr(index_details, 0, 5);
+	num = PQntuples(index_details);
+
+	initStringInfo(&sql);
+	initStringInfo(&sql_drop);
+
+	appendStringInfoString(&sql, "DROP INDEX CONCURRENTLY IF EXISTS ");
+	appendStringInfo(&sql, "\"%s\".",  schema_name);
+
+	for (int i = 0; i < num; i++)
+	{
+		Oid			index = getoid(index_details, i, 1);
+
+		resetStringInfo(&sql_drop);
+		appendStringInfo(&sql_drop, "%s\"index_%u\"", sql.data, index);
+		command(sql_drop.data, 0, NULL);
+	}
+	termStringInfo(&sql_drop);
+	termStringInfo(&sql);
+}
+
 /*
  * Indexes of a table are repacked.
  */
@@ -2086,7 +2120,7 @@ repack_table_indexes(PGresult *index_details)
 {
 	bool				ret = false;
 	PGresult			*res = NULL, *res2 = NULL;
-	StringInfoData		sql, sql_drop;
+	StringInfoData		sql;
 	char				buffer[2][12];
 	const char			*create_idx, *schema_name, *table_name, *params[3];
 	Oid					table, index;
@@ -2117,6 +2151,8 @@ repack_table_indexes(PGresult *index_details)
 		ereport(ERROR, (errcode(EINVAL),
 			errmsg("Unable to obtain advisory lock on \"%s\"", table_name)));
 
+	pgut_atexit_push(repack_cleanup_index, index_details);
+
 	for (i = 0; i < num; i++)
 	{
 		char *isvalid = getstr(index_details, i, 2);
@@ -2241,30 +2277,16 @@ repack_table_indexes(PGresult *index_details)
 	pgut_command(connection, "COMMIT", 0, NULL);
 	ret = true;
 
-drop_idx:
-	resetStringInfo(&sql);
-	initStringInfo(&sql_drop);
-	appendStringInfoString(&sql, "DROP INDEX CONCURRENTLY ");
-	appendStringInfo(&sql, "\"%s\".",  schema_name);
+	pgut_atexit_pop(repack_cleanup_index, index_details);
 
-	for (i = 0; i < num; i++)
-	{
-		index = getoid(index_details, i, 1);
-		if (repacked_indexes[i])
-		{
-			initStringInfo(&sql_drop);
-			appendStringInfo(&sql_drop, "%s\"index_%u\"", sql.data, index);
-			command(sql_drop.data, 0, NULL);
-		}
-		else
-			elog(INFO, "Skipping drop of index_%u", index);
-	}
-	termStringInfo(&sql_drop);
-	termStringInfo(&sql);
+drop_idx:
+	if (num_repacked > 0)
+		repack_cleanup_index(false, index_details);
 
 done:
 	CLEARPGRES(res);
 	free(repacked_indexes);
+	termStringInfo(&sql);
 
 	return ret;
 }