From 604ffd280b955100e5fc24649ee4d42a6f3ebf35 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 25 May 2007 17:54:25 +0000
Subject: [PATCH] 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/explain.c | 96 +++++++++++++++-------
src/backend/commands/prepare.c | 21 +----
src/backend/executor/nodeBitmapIndexscan.c | 18 +++-
src/backend/executor/nodeIndexscan.c | 18 +++-
src/backend/optimizer/plan/planner.c | 26 +++++-
src/backend/optimizer/util/plancat.c | 13 ++-
src/include/commands/explain.h | 18 +++-
src/include/optimizer/plancat.h | 9 +-
src/include/optimizer/planner.h | 11 ++-
9 files changed, 168 insertions(+), 62 deletions(-)
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 608ebf93ce8..39e8073f55b 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994-5, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.163 2007/05/04 21:29:52 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.164 2007/05/25 17:54:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -33,6 +33,12 @@
#include "utils/tuplesort.h"
+/* Hook for plugins to get control in ExplainOneQuery() */
+ExplainOneQuery_hook_type ExplainOneQuery_hook = NULL;
+/* Hook for plugins to get control in explain_get_index_name() */
+explain_get_index_name_hook_type explain_get_index_name_hook = NULL;
+
+
typedef struct ExplainState
{
/* options */
@@ -61,6 +67,8 @@ static void show_sort_keys(Plan *sortplan, int nkeys, AttrNumber *keycols,
StringInfo str, int indent, ExplainState *es);
static void show_sort_info(SortState *sortstate,
StringInfo str, int indent, ExplainState *es);
+static const char *explain_get_index_name(Oid indexId);
+
/*
* ExplainQuery -
@@ -140,9 +148,6 @@ static void
ExplainOneQuery(Query *query, ExplainStmt *stmt, const char *queryString,
ParamListInfo params, TupOutputState *tstate)
{
- PlannedStmt *plan;
- QueryDesc *queryDesc;
-
/* planner will not cope with utility statements */
if (query->commandType == CMD_UTILITY)
{
@@ -151,25 +156,19 @@ ExplainOneQuery(Query *query, ExplainStmt *stmt, const char *queryString,
return;
}
- /* plan the query */
- plan = planner(query, 0, params);
-
- /*
- * 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();
+ /* if an advisor plugin is present, let it manage things */
+ if (ExplainOneQuery_hook)
+ (*ExplainOneQuery_hook) (query, stmt, queryString, params, tstate);
+ else
+ {
+ PlannedStmt *plan;
- /* Create a QueryDesc requesting no output */
- queryDesc = CreateQueryDesc(plan,
- ActiveSnapshot, InvalidSnapshot,
- None_Receiver, params,
- stmt->analyze);
+ /* plan the query */
+ plan = planner(query, 0, params);
- ExplainOnePlan(queryDesc, stmt, tstate);
+ /* run it (if needed) and produce output */
+ ExplainOnePlan(plan, params, stmt, tstate);
+ }
}
/*
@@ -210,20 +209,35 @@ ExplainOneUtility(Node *utilityStmt, ExplainStmt *stmt,
* not running the query. No cursor will be created, however.
*
* This is exported because it's called back from prepare.c in the
- * EXPLAIN EXECUTE case
- *
- * Note: the passed-in QueryDesc is freed when we're done with it
+ * EXPLAIN EXECUTE case, and because an index advisor plugin would need
+ * to call it.
*/
void
-ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt,
- TupOutputState *tstate)
+ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
+ ExplainStmt *stmt, TupOutputState *tstate)
{
+ QueryDesc *queryDesc;
instr_time starttime;
double totaltime = 0;
ExplainState *es;
StringInfoData buf;
int eflags;
+ /*
+ * 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 */
+ queryDesc = CreateQueryDesc(plannedstmt,
+ ActiveSnapshot, InvalidSnapshot,
+ None_Receiver, params,
+ stmt->analyze);
+
INSTR_TIME_SET_CURRENT(starttime);
/* If analyzing, we need to cope with queued triggers */
@@ -592,7 +606,7 @@ explain_outNode(StringInfo str,
if (ScanDirectionIsBackward(((IndexScan *) plan)->indexorderdir))
appendStringInfoString(str, " Backward");
appendStringInfo(str, " using %s",
- quote_identifier(get_rel_name(((IndexScan *) plan)->indexid)));
+ explain_get_index_name(((IndexScan *) plan)->indexid));
/* FALL THRU */
case T_SeqScan:
case T_BitmapHeapScan:
@@ -618,7 +632,7 @@ explain_outNode(StringInfo str,
break;
case T_BitmapIndexScan:
appendStringInfo(str, " on %s",
- quote_identifier(get_rel_name(((BitmapIndexScan *) plan)->indexid)));
+ explain_get_index_name(((BitmapIndexScan *) plan)->indexid));
break;
case T_SubqueryScan:
if (((Scan *) plan)->scanrelid > 0)
@@ -1150,3 +1164,29 @@ show_sort_info(SortState *sortstate,
pfree(sortinfo);
}
}
+
+/*
+ * Fetch the name of an index in an EXPLAIN
+ *
+ * We allow plugins to get control here so that plans involving hypothetical
+ * indexes can be explained.
+ */
+static const char *
+explain_get_index_name(Oid indexId)
+{
+ const char *result;
+
+ if (explain_get_index_name_hook)
+ result = (*explain_get_index_name_hook) (indexId);
+ else
+ result = NULL;
+ if (result == NULL)
+ {
+ /* default behavior: look in the catalogs and quote it */
+ result = get_rel_name(indexId);
+ if (result == NULL)
+ elog(ERROR, "cache lookup failed for index %u", indexId);
+ result = quote_identifier(result);
+ }
+ return result;
+}
diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index 997f66c8188..de999a36376 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
{
diff --git a/src/backend/executor/nodeBitmapIndexscan.c b/src/backend/executor/nodeBitmapIndexscan.c
index d3fbf348332..6c14b8a4130 100644
--- a/src/backend/executor/nodeBitmapIndexscan.c
+++ b/src/backend/executor/nodeBitmapIndexscan.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.22 2007/01/05 22:19:28 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.23 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -198,10 +198,12 @@ ExecEndBitmapIndexScan(BitmapIndexScanState *node)
#endif
/*
- * close the index relation
+ * close the index relation (no-op if we didn't open it)
*/
- index_endscan(indexScanDesc);
- index_close(indexRelationDesc, NoLock);
+ if (indexScanDesc)
+ index_endscan(indexScanDesc);
+ if (indexRelationDesc)
+ index_close(indexRelationDesc, NoLock);
}
/* ----------------------------------------------------------------
@@ -256,6 +258,14 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate, int eflags)
indexstate->ss.ss_currentRelation = NULL;
indexstate->ss.ss_currentScanDesc = NULL;
+ /*
+ * If we are just doing EXPLAIN (ie, aren't going to run the plan),
+ * stop here. This allows an index-advisor plugin to EXPLAIN a plan
+ * containing references to nonexistent indexes.
+ */
+ if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
+ return indexstate;
+
/*
* Open the index relation.
*
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index d9136de0035..8c22e3ade0e 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/nodeIndexscan.c,v 1.121 2007/04/06 22:33:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/nodeIndexscan.c,v 1.122 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -415,10 +415,12 @@ ExecEndIndexScan(IndexScanState *node)
ExecClearTuple(node->ss.ss_ScanTupleSlot);
/*
- * close the index relation
+ * close the index relation (no-op if we didn't open it)
*/
- index_endscan(indexScanDesc);
- index_close(indexRelationDesc, NoLock);
+ if (indexScanDesc)
+ index_endscan(indexScanDesc);
+ if (indexRelationDesc)
+ index_close(indexRelationDesc, NoLock);
/*
* close the heap relation.
@@ -520,6 +522,14 @@ ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
*/
ExecAssignScanType(&indexstate->ss, RelationGetDescr(currentRelation));
+ /*
+ * If we are just doing EXPLAIN (ie, aren't going to run the plan),
+ * stop here. This allows an index-advisor plugin to EXPLAIN a plan
+ * containing references to nonexistent indexes.
+ */
+ if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
+ return indexstate;
+
/*
* Open the index relation.
*
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 366c50f2730..0f9776cdca2 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.219 2007/05/04 01:13:44 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.220 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -42,6 +42,10 @@
#include "utils/syscache.h"
+/* Hook for plugins to get control in planner() */
+planner_hook_type planner_hook = NULL;
+
+
/* Expression kind codes for preprocess_expression */
#define EXPRKIND_QUAL 0
#define EXPRKIND_TARGET 1
@@ -79,9 +83,29 @@ static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
*
* Query optimizer entry point
*
+ * To support loadable plugins that monitor or modify planner behavior,
+ * we provide a hook variable that lets a plugin get control before and
+ * after the standard planning process. The plugin would normally call
+ * standard_planner().
+ *
+ * Note to plugin authors: standard_planner() scribbles on its Query input,
+ * so you'd better copy that data structure if you want to plan more than once.
+ *
*****************************************************************************/
PlannedStmt *
planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
+{
+ PlannedStmt *result;
+
+ if (planner_hook)
+ result = (*planner_hook) (parse, cursorOptions, boundParams);
+ else
+ result = standard_planner(parse, cursorOptions, boundParams);
+ return result;
+}
+
+PlannedStmt *
+standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
{
PlannedStmt *result;
PlannerGlobal *glob;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 662fcbaaf8e..605e7f64eed 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.134 2007/04/21 21:01:45 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.135 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -40,6 +40,9 @@
/* GUC parameter */
bool constraint_exclusion = false;
+/* Hook for plugins to get control in get_relation_info() */
+get_relation_info_hook_type get_relation_info_hook = NULL;
+
static void estimate_rel_size(Relation rel, int32 *attr_widths,
BlockNumber *pages, double *tuples);
@@ -279,6 +282,14 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
rel->indexlist = indexinfos;
heap_close(relation, NoLock);
+
+ /*
+ * Allow a plugin to editorialize on the info we obtained from the
+ * catalogs. Actions might include altering the assumed relation size,
+ * removing an index, or adding a hypothetical index to the indexlist.
+ */
+ if (get_relation_info_hook)
+ (*get_relation_info_hook) (root, relationObjectId, inhparent, rel);
}
/*
diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index 42879ce5a40..73bf41e49c1 100644
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994-5, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/commands/explain.h,v 1.30 2007/03/13 00:33:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/explain.h,v 1.31 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -15,6 +15,18 @@
#include "executor/executor.h"
+/* Hook for plugins to get control in ExplainOneQuery() */
+typedef void (*ExplainOneQuery_hook_type) (Query *query,
+ ExplainStmt *stmt,
+ const char *queryString,
+ ParamListInfo params,
+ TupOutputState *tstate);
+extern DLLIMPORT ExplainOneQuery_hook_type ExplainOneQuery_hook;
+
+/* Hook for plugins to get control in explain_get_index_name() */
+typedef const char * (*explain_get_index_name_hook_type) (Oid indexId);
+extern DLLIMPORT explain_get_index_name_hook_type explain_get_index_name_hook;
+
extern void ExplainQuery(ExplainStmt *stmt, const char *queryString,
ParamListInfo params, DestReceiver *dest);
@@ -26,7 +38,7 @@ extern void ExplainOneUtility(Node *utilityStmt, ExplainStmt *stmt,
ParamListInfo params,
TupOutputState *tstate);
-extern void ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt,
- TupOutputState *tstate);
+extern void ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
+ ExplainStmt *stmt, TupOutputState *tstate);
#endif /* EXPLAIN_H */
diff --git a/src/include/optimizer/plancat.h b/src/include/optimizer/plancat.h
index 31391d29a90..a19ba780eed 100644
--- a/src/include/optimizer/plancat.h
+++ b/src/include/optimizer/plancat.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/optimizer/plancat.h,v 1.43 2007/01/05 22:19:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/plancat.h,v 1.44 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -16,6 +16,13 @@
#include "nodes/relation.h"
+/* Hook for plugins to get control in get_relation_info() */
+typedef void (*get_relation_info_hook_type) (PlannerInfo *root,
+ Oid relationObjectId,
+ bool inhparent,
+ RelOptInfo *rel);
+extern DLLIMPORT get_relation_info_hook_type get_relation_info_hook;
+
extern void get_relation_info(PlannerInfo *root, Oid relationObjectId,
bool inhparent, RelOptInfo *rel);
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index b568a7dbe82..a08a83ae718 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/optimizer/planner.h,v 1.39 2007/04/16 01:14:58 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/planner.h,v 1.40 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -18,8 +18,17 @@
#include "nodes/relation.h"
+/* Hook for plugins to get control in planner() */
+typedef PlannedStmt * (*planner_hook_type) (Query *parse,
+ int cursorOptions,
+ ParamListInfo boundParams);
+extern DLLIMPORT planner_hook_type planner_hook;
+
+
extern PlannedStmt *planner(Query *parse, int cursorOptions,
ParamListInfo boundParams);
+extern PlannedStmt *standard_planner(Query *parse, int cursorOptions,
+ ParamListInfo boundParams);
extern Plan *subquery_planner(PlannerGlobal *glob, Query *parse,
Index level, double tuple_fraction,
PlannerInfo **subroot);
--
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