From 14f84cd82103c3797980125bb44a76446e0c0dc6 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 9 Aug 1999 03:16:47 +0000
Subject: [PATCH] Store -1 in attdisbursion to signal 'no duplicates in
column'. Centralize att_disbursion readout logic.
---
src/backend/commands/vacuum.c | 62 +++++++++++++++-----------
src/backend/optimizer/path/joinpath.c | 20 ++-------
src/backend/utils/adt/selfuncs.c | 63 ++-------------------------
3 files changed, 43 insertions(+), 102 deletions(-)
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 0418a8d3a38..b480b44f347 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.117 1999/08/08 17:13:10 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.118 1999/08/09 03:16:47 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2346,36 +2346,46 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
}
else if (stats->null_cnt <= 1 && stats->best_cnt == 1)
{
- /* looks like we have a unique-key attribute */
- double total = ((double) stats->nonnull_cnt) + ((double) stats->null_cnt);
-
- selratio = 1.0 / total;
- }
- else if (VacAttrStatsLtGtValid(stats) && stats->min_cnt + stats->max_cnt == stats->nonnull_cnt)
- {
- /* exact result when there are just 1 or 2 values... */
- double min_cnt_d = stats->min_cnt,
- max_cnt_d = stats->max_cnt,
- null_cnt_d = stats->null_cnt;
- double total = ((double) stats->nonnull_cnt) + null_cnt_d;
-
- selratio = (min_cnt_d * min_cnt_d + max_cnt_d * max_cnt_d + null_cnt_d * null_cnt_d) / (total * total);
+ /* looks like we have a unique-key attribute ---
+ * flag this with special -1.0 flag value.
+ *
+ * The correct disbursion is 1.0/numberOfRows, but since
+ * the relation row count can get updated without
+ * recomputing disbursion, we want to store a "symbolic"
+ * value and figure 1.0/numberOfRows on the fly.
+ */
+ selratio = -1;
}
else
{
- double most = (double) (stats->best_cnt > stats->null_cnt ? stats->best_cnt : stats->null_cnt);
- double total = ((double) stats->nonnull_cnt) + ((double) stats->null_cnt);
+ if (VacAttrStatsLtGtValid(stats) &&
+ stats->min_cnt + stats->max_cnt == stats->nonnull_cnt)
+ {
+ /* exact result when there are just 1 or 2 values... */
+ double min_cnt_d = stats->min_cnt,
+ max_cnt_d = stats->max_cnt,
+ null_cnt_d = stats->null_cnt;
+ double total = ((double) stats->nonnull_cnt) + null_cnt_d;
- /*
- * we assume count of other values are 20% of best
- * count in table
- */
- selratio = (most * most + 0.20 * most * (total - most)) / (total * total);
+ selratio = (min_cnt_d * min_cnt_d + max_cnt_d * max_cnt_d + null_cnt_d * null_cnt_d) / (total * total);
+ }
+ else
+ {
+ double most = (double) (stats->best_cnt > stats->null_cnt ? stats->best_cnt : stats->null_cnt);
+ double total = ((double) stats->nonnull_cnt) + ((double) stats->null_cnt);
+
+ /*
+ * we assume count of other values are 20% of best
+ * count in table
+ */
+ selratio = (most * most + 0.20 * most * (total - most)) / (total * total);
+ }
+ /* Make sure calculated values are in-range */
+ if (selratio < 0.0)
+ selratio = 0.0;
+ else if (selratio > 1.0)
+ selratio = 1.0;
}
- if (selratio < 0.0)
- selratio = 0.0;
- else if (selratio > 1.0)
- selratio = 1.0;
attp->attdisbursion = selratio;
/*
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 57688deeb85..4a7018aa64a 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.43 1999/08/06 04:00:15 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.44 1999/08/09 03:16:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -23,7 +23,7 @@
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "parser/parsetree.h"
-#include "utils/syscache.h"
+#include "utils/lsyscache.h"
static Path *best_innerjoin(List *join_paths, List *outer_relid);
static List *sort_inner_and_outer(RelOptInfo *joinrel, RelOptInfo *outerrel, RelOptInfo *innerrel,
@@ -586,7 +586,6 @@ hash_inner_and_outer(Query *root,
/*
* Estimate disbursion of the specified Var
- * Generate some kind of estimate, no matter what...
*
* We use a default of 0.1 if we can't figure out anything better.
* This will typically discourage use of a hash rather strongly,
@@ -598,24 +597,11 @@ static Cost
estimate_disbursion(Query *root, Var *var)
{
Oid relid;
- HeapTuple atp;
- double disbursion;
if (! IsA(var, Var))
return 0.1;
relid = getrelid(var->varno, root->rtable);
- atp = SearchSysCacheTuple(ATTNUM,
- ObjectIdGetDatum(relid),
- Int16GetDatum(var->varattno),
- 0, 0);
- if (! HeapTupleIsValid(atp))
- return 0.1;
-
- disbursion = ((Form_pg_attribute) GETSTRUCT(atp))->attdisbursion;
- if (disbursion > 0.0)
- return disbursion;
-
- return 0.1;
+ return (Cost) get_attdisbursion(relid, var->varattno, 0.1);
}
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index a0e0c7ad7fc..298c7aeed16 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.37 1999/08/02 02:05:41 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.38 1999/08/09 03:16:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -52,7 +52,6 @@ static bool getattstatistics(Oid relid, AttrNumber attnum,
Datum *commonval,
Datum *loval,
Datum *hival);
-static double getattdisbursion(Oid relid, AttrNumber attnum);
/*
@@ -172,7 +171,7 @@ eqsel(Oid opid,
/* No VACUUM ANALYZE stats available, so make a guess using
* the disbursion stat (if we have that, which is unlikely...)
*/
- selec = getattdisbursion(relid, attno);
+ selec = get_attdisbursion(relid, attno, 0.01);
}
*result = (float64data) selec;
@@ -374,8 +373,8 @@ eqjoinsel(Oid opid,
*result = 0.1;
else
{
- num1 = getattdisbursion(relid1, attno1);
- num2 = getattdisbursion(relid2, attno2);
+ num1 = get_attdisbursion(relid1, attno1, 0.01);
+ num2 = get_attdisbursion(relid2, attno2, 0.01);
max = (num1 > num2) ? num1 : num2;
if (max <= 0)
*result = 1.0;
@@ -675,60 +674,6 @@ getattstatistics(Oid relid, AttrNumber attnum, Oid typid, int32 typmod,
return true;
}
-/*
- * getattdisbursion
- * Retrieve the disbursion statistic for an attribute,
- * or produce an estimate if no info is available.
- */
-static double
-getattdisbursion(Oid relid, AttrNumber attnum)
-{
- HeapTuple atp;
- double disbursion;
- int32 ntuples;
-
- atp = SearchSysCacheTuple(ATTNUM,
- ObjectIdGetDatum(relid),
- Int16GetDatum(attnum),
- 0, 0);
- if (!HeapTupleIsValid(atp))
- {
- /* this should not happen */
- elog(ERROR, "getattdisbursion: no attribute tuple %u %d",
- relid, attnum);
- return 0.1;
- }
-
- disbursion = ((Form_pg_attribute) GETSTRUCT(atp))->attdisbursion;
- if (disbursion > 0.0)
- return disbursion;
-
- /* VACUUM ANALYZE has not stored a disbursion statistic for us.
- * Produce an estimate = 1/numtuples. This may produce
- * unreasonably small estimates for large tables, so limit
- * the estimate to no less than 0.01.
- */
- atp = SearchSysCacheTuple(RELOID,
- ObjectIdGetDatum(relid),
- 0, 0, 0);
- if (!HeapTupleIsValid(atp))
- {
- /* this should not happen */
- elog(ERROR, "getattdisbursion: no relation tuple %u", relid);
- return 0.1;
- }
-
- ntuples = ((Form_pg_class) GETSTRUCT(atp))->reltuples;
-
- if (ntuples > 0)
- disbursion = 1.0 / (double) ntuples;
-
- if (disbursion < 0.01)
- disbursion = 0.01;
-
- return disbursion;
-}
-
float64
btreesel(Oid operatorObjectId,
Oid indrelid,
--
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