From 42a8ab0a1429b4ba78a35ad8b210734d1561d644 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Mon, 1 Feb 2010 15:43:36 +0000 Subject: [PATCH] Augment EXPLAIN output with more details on Hash nodes. We show the number of buckets, the number of batches (and also the original number if it has changed), and the peak space used by the hash table. Minor executor changes to track peak space used. --- src/backend/commands/explain.c | 48 ++++++++++++++++++++++++++++++++- src/backend/executor/nodeHash.c | 11 +++++++- src/include/executor/hashjoin.h | 3 ++- 3 files changed, 59 insertions(+), 3 deletions(-) diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 37647e5739..8c9b060e6b 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 1.199 2010/01/15 22:36:29 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.200 2010/02/01 15:43:35 rhaas Exp $ * *------------------------------------------------------------------------- */ @@ -20,6 +20,7 @@ #include "commands/explain.h" #include "commands/prepare.h" #include "commands/trigger.h" +#include "executor/hashjoin.h" #include "executor/instrument.h" #include "optimizer/clauses.h" #include "optimizer/planner.h" @@ -67,6 +68,7 @@ static void show_upper_qual(List *qual, const char *qlabel, Plan *plan, ExplainState *es); static void show_sort_keys(Plan *sortplan, ExplainState *es); static void show_sort_info(SortState *sortstate, ExplainState *es); +static void show_hash_info(HashState *hashstate, ExplainState *es); static const char *explain_get_index_name(Oid indexId); static void ExplainScanTarget(Scan *plan, ExplainState *es); static void ExplainMemberNodes(List *plans, PlanState **planstate, @@ -1052,6 +1054,9 @@ ExplainNode(Plan *plan, PlanState *planstate, "One-Time Filter", plan, es); show_upper_qual(plan->qual, "Filter", plan, es); break; + case T_Hash: + show_hash_info((HashState *) planstate, es); + break; default: break; } @@ -1404,6 +1409,47 @@ show_sort_info(SortState *sortstate, ExplainState *es) } } +/* + * Show information on hash buckets/batches. + */ +static void +show_hash_info(HashState *hashstate, ExplainState *es) +{ + HashJoinTable hashtable; + + Assert(IsA(hashstate, HashState)); + hashtable = hashstate->hashtable; + + if (hashtable) + { + long spacePeakKb = (hashtable->spacePeak + 1023) / 1024; + if (es->format != EXPLAIN_FORMAT_TEXT) + { + ExplainPropertyLong("Hash Buckets", hashtable->nbuckets, es); + ExplainPropertyLong("Hash Batches", hashtable->nbatch, es); + ExplainPropertyLong("Original Hash Batches", + hashtable->nbatch_original, es); + ExplainPropertyLong("Peak Memory Usage", spacePeakKb, es); + } + else if (hashtable->nbatch_original != hashtable->nbatch) + { + appendStringInfoSpaces(es->str, es->indent * 2); + appendStringInfo(es->str, + "Buckets: %d Batches: %d (originally %d) Memory Usage: %ldkB\n", + hashtable->nbuckets, hashtable->nbatch, + hashtable->nbatch_original, spacePeakKb); + } + else + { + appendStringInfoSpaces(es->str, es->indent * 2); + appendStringInfo(es->str, + "Buckets: %d Batches: %d Memory Usage: %ldkB\n", + hashtable->nbuckets, hashtable->nbatch, + spacePeakKb); + } + } +} + /* * Fetch the name of an index in an EXPLAIN * diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c index 558a780229..86bbef9be0 100644 --- a/src/backend/executor/nodeHash.c +++ b/src/backend/executor/nodeHash.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.126 2010/01/04 02:44:39 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.127 2010/02/01 15:43:36 rhaas Exp $ * *------------------------------------------------------------------------- */ @@ -287,6 +287,7 @@ ExecHashTableCreate(Hash *node, List *hashOperators) hashtable->innerBatchFile = NULL; hashtable->outerBatchFile = NULL; hashtable->spaceUsed = 0; + hashtable->spacePeak = 0; hashtable->spaceAllowed = work_mem * 1024L; hashtable->spaceUsedSkew = 0; hashtable->spaceAllowedSkew = @@ -719,6 +720,8 @@ ExecHashTableInsert(HashJoinTable hashtable, hashTuple->next = hashtable->buckets[bucketno]; hashtable->buckets[bucketno] = hashTuple; hashtable->spaceUsed += hashTupleSize; + if (hashtable->spaceUsed > hashtable->spacePeak) + hashtable->spacePeak = hashtable->spaceUsed; if (hashtable->spaceUsed > hashtable->spaceAllowed) ExecHashIncreaseNumBatches(hashtable); } @@ -1071,6 +1074,8 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse) + mcvsToUse * sizeof(int); hashtable->spaceUsedSkew += nbuckets * sizeof(HashSkewBucket *) + mcvsToUse * sizeof(int); + if (hashtable->spaceUsed > hashtable->spacePeak) + hashtable->spacePeak = hashtable->spaceUsed; /* * Create a skew bucket for each MCV hash value. @@ -1119,6 +1124,8 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse) hashtable->nSkewBuckets++; hashtable->spaceUsed += SKEW_BUCKET_OVERHEAD; hashtable->spaceUsedSkew += SKEW_BUCKET_OVERHEAD; + if (hashtable->spaceUsed > hashtable->spacePeak) + hashtable->spacePeak = hashtable->spaceUsed; } free_attstatsslot(node->skewColType, @@ -1205,6 +1212,8 @@ ExecHashSkewTableInsert(HashJoinTable hashtable, /* Account for space used, and back off if we've used too much */ hashtable->spaceUsed += hashTupleSize; hashtable->spaceUsedSkew += hashTupleSize; + if (hashtable->spaceUsed > hashtable->spacePeak) + hashtable->spacePeak = hashtable->spaceUsed; while (hashtable->spaceUsedSkew > hashtable->spaceAllowedSkew) ExecHashRemoveNextSkewBucket(hashtable); diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h index 4e90cbd353..4ac6ae3ce8 100644 --- a/src/include/executor/hashjoin.h +++ b/src/include/executor/hashjoin.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/executor/hashjoin.h,v 1.52 2010/01/02 16:58:03 momjian Exp $ + * $PostgreSQL: pgsql/src/include/executor/hashjoin.h,v 1.53 2010/02/01 15:43:36 rhaas Exp $ * *------------------------------------------------------------------------- */ @@ -149,6 +149,7 @@ typedef struct HashJoinTableData Size spaceUsed; /* memory space currently used by tuples */ Size spaceAllowed; /* upper limit for space used */ + Size spacePeak; /* peak space used */ Size spaceUsedSkew; /* skew hash table's current space usage */ Size spaceAllowedSkew; /* upper limit for skew hashtable */