From 604ffd280b955100e5fc24649ee4d42a6f3ebf35 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 25 May 2007 17:54:25 +0000 Subject: Create hooks to let a loadable plugin monitor (or even replace) the planner and/or create plans for hypothetical situations; in particular, investigate plans that would be generated using hypothetical indexes. This is a heavily-rewritten version of the hooks proposed by Gurjeet Singh for his Index Advisor project. In this formulation, the index advisor can be entirely a loadable module instead of requiring a significant part to be in the core backend, and plans can be generated for hypothetical indexes without requiring the creation and rolling-back of system catalog entries. The index advisor patch as-submitted is not compatible with these hooks, but it needs significant work anyway due to other 8.2-to-8.3 planner changes. With these hooks in the core backend, development of the advisor can proceed as a pgfoundry project. --- src/backend/commands/prepare.c | 21 ++------------------- 1 file changed, 2 insertions(+), 19 deletions(-) (limited to 'src/backend/commands/prepare.c') diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c index 997f66c818..de999a3637 100644 --- a/src/backend/commands/prepare.c +++ b/src/backend/commands/prepare.c @@ -10,7 +10,7 @@ * Copyright (c) 2002-2007, PostgreSQL Global Development Group * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.75 2007/04/27 22:05:47 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.76 2007/05/25 17:54:25 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -678,8 +678,6 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt, if (IsA(pstmt, PlannedStmt)) { - QueryDesc *qdesc; - if (execstmt->into) { if (pstmt->commandType != CMD_SELECT || @@ -694,22 +692,7 @@ ExplainExecuteQuery(ExecuteStmt *execstmt, ExplainStmt *stmt, pstmt->intoClause = execstmt->into; } - /* - * Update snapshot command ID to ensure this query sees results of - * any previously executed queries. (It's a bit cheesy to modify - * ActiveSnapshot without making a copy, but for the limited ways - * in which EXPLAIN can be invoked, I think it's OK, because the - * active snapshot shouldn't be shared with anything else anyway.) - */ - ActiveSnapshot->curcid = GetCurrentCommandId(); - - /* Create a QueryDesc requesting no output */ - qdesc = CreateQueryDesc(pstmt, - ActiveSnapshot, InvalidSnapshot, - None_Receiver, - paramLI, stmt->analyze); - - ExplainOnePlan(qdesc, stmt, tstate); + ExplainOnePlan(pstmt, paramLI, stmt, tstate); } else { -- cgit v1.2.1