database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-07 19:06:32 +03:00
Code Activity

Rewrite of planner statistics-gathering code. ANALYZE is now available as

Browse Source 
a separate statement (though it can still be invoked as part of VACUUM, too).
pg_statistic redesigned to be more flexible about what statistics are
stored.  ANALYZE now collects a list of several of the most common values,
not just one, plus a histogram (not just the min and max values).  Random
sampling is used to make the process reasonably fast even on very large
tables.  The number of values and histogram bins collected is now
user-settable via an ALTER TABLE command.

There is more still to do; the new stats are not being used everywhere
they could be in the planner.  But the remaining changes for this project
should be localized, and the behavior is already better than before.

A not-very-related change is that sorting now makes use of btree comparison
routines if it can find one, rather than invoking '<' twice.
This commit is contained in:
Tom Lane
2001-05-07 00:43:27 +00:00
parent 9583aea9d0
commit f905d65ee3
66 changed files with 4131 additions and 2063 deletions
Download Patch File Download Diff File Expand all files Collapse all files

82
src/backend/catalog/index.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/index.c,v 1.145 2001/04/02 14:34:25 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/index.c,v 1.146 2001/05/07 00:43:17 tgl Exp $
*
*
* INTERFACE ROUTINES
@@ -55,7 +55,7 @@
*/
#define AVG_ATTR_SIZE 8
#define NTUPLES_PER_PAGE(natts) \
((BLCKSZ - MAXALIGN(sizeof (PageHeaderData))) / \
((BLCKSZ - MAXALIGN(sizeof(PageHeaderData))) / \
((natts) * AVG_ATTR_SIZE + MAXALIGN(sizeof(HeapTupleHeaderData))))
/* non-export function prototypes */
@@ -98,39 +98,6 @@ IsReindexProcessing(void)
return reindexing;
}
/* ----------------------------------------------------------------
* sysatts is a structure containing attribute tuple forms
* for system attributes (numbered -1, -2, ...). This really
* should be generated or eliminated or moved elsewhere. -cim 1/19/91
*
* typedef struct FormData_pg_attribute {
* Oid attrelid;
* NameData attname;
* Oid atttypid;
* uint32 attnvals;
* int16 attlen;
* AttrNumber attnum;
* uint32 attnelems;
* int32 attcacheoff;
* int32 atttypmod;
* bool attbyval;
* bool attisset;
* char attalign;
* bool attnotnull;
* bool atthasdef;
* } FormData_pg_attribute;
*
* ----------------------------------------------------------------
*/
static FormData_pg_attribute sysatts[] = {
{0, {"ctid"}, TIDOID, 0, 6, -1, 0, -1, -1, '\0', 'p', '\0', 'i', '\0', '\0'},
{0, {"oid"}, OIDOID, 0, 4, -2, 0, -1, -1, '\001', 'p', '\0', 'i', '\0', '\0'},
{0, {"xmin"}, XIDOID, 0, 4, -3, 0, -1, -1, '\001', 'p', '\0', 'i', '\0', '\0'},
{0, {"cmin"}, CIDOID, 0, 4, -4, 0, -1, -1, '\001', 'p', '\0', 'i', '\0', '\0'},
{0, {"xmax"}, XIDOID, 0, 4, -5, 0, -1, -1, '\001', 'p', '\0', 'i', '\0', '\0'},
{0, {"cmax"}, CIDOID, 0, 4, -6, 0, -1, -1, '\001', 'p', '\0', 'i', '\0', '\0'},
};
/* ----------------------------------------------------------------
* GetHeapRelationOid
* ----------------------------------------------------------------
@@ -250,7 +217,6 @@ ConstructTupleDescriptor(Relation heapRelation,
for (i = 0; i < numatts; i++)
{
AttrNumber atnum; /* attributeNumber[attributeOffset] */
AttrNumber atind;
Form_pg_attribute from;
Form_pg_attribute to;
@@ -264,16 +230,9 @@ ConstructTupleDescriptor(Relation heapRelation,
{
/*
* here we are indexing on a system attribute (-1...-n) so we
* convert atnum into a usable index 0...n-1 so we can use it
* to dereference the array sysatts[] which stores tuple
* descriptor information for system attributes.
* here we are indexing on a system attribute (-1...-n)
*/
if (atnum <= FirstLowInvalidHeapAttributeNumber || atnum >= 0)
elog(ERROR, "Cannot create index on system attribute: attribute number out of range (%d)", atnum);
atind = (-atnum) - 1;
from = &sysatts[atind];
from = SystemAttributeDefinition(atnum);
}
else
{
@@ -284,9 +243,8 @@ ConstructTupleDescriptor(Relation heapRelation,
if (atnum > natts)
elog(ERROR, "Cannot create index: attribute %d does not exist",
atnum);
atind = AttrNumberGetAttrOffset(atnum);
from = heapTupDesc->attrs[atind];
from = heapTupDesc->attrs[AttrNumberGetAttrOffset(atnum)];
}
/*
@@ -303,10 +261,10 @@ ConstructTupleDescriptor(Relation heapRelation,
*/
to->attnum = i + 1;
to->attdispersion = 0.0;
to->attstattarget = 0;
to->attcacheoff = -1;
to->attnotnull = false;
to->atthasdef = false;
to->attcacheoff = -1;
/*
* We do not yet have the correct relation OID for the index, so
@@ -1542,10 +1500,14 @@ setNewRelfilenode(Relation relation)
/* ----------------
* UpdateStats
*
* Update pg_class' relpages and reltuples statistics for the given relation
* (which can be either a table or an index). Note that this is not used
* in the context of VACUUM.
* ----------------
*/
void
UpdateStats(Oid relid, long reltuples)
UpdateStats(Oid relid, double reltuples)
{
Relation whichRel;
Relation pg_class;
@@ -1636,6 +1598,10 @@ UpdateStats(Oid relid, long reltuples)
* with zero size statistics until a VACUUM is done. The optimizer
* will generate very bad plans if the stats claim the table is empty
* when it is actually sizable. See also CREATE TABLE in heap.c.
*
* Note: this path is also taken during bootstrap, because bootstrap.c
* passes reltuples = 0 after loading a table. We have to estimate some
* number for reltuples based on the actual number of pages.
*/
relpages = RelationGetNumberOfBlocks(whichRel);
@@ -1689,15 +1655,15 @@ UpdateStats(Oid relid, long reltuples)
for (i = 0; i < Natts_pg_class; i++)
{
nulls[i] = heap_attisnull(tuple, i + 1) ? 'n' : ' ';
nulls[i] = ' ';
replace[i] = ' ';
values[i] = (Datum) NULL;
}
replace[Anum_pg_class_relpages - 1] = 'r';
values[Anum_pg_class_relpages - 1] = (Datum) relpages;
values[Anum_pg_class_relpages - 1] = Int32GetDatum(relpages);
replace[Anum_pg_class_reltuples - 1] = 'r';
values[Anum_pg_class_reltuples - 1] = (Datum) reltuples;
values[Anum_pg_class_reltuples - 1] = Float4GetDatum((float4) reltuples);
newtup = heap_modifytuple(tuple, pg_class, values, nulls, replace);
simple_heap_update(pg_class, &tuple->t_self, newtup);
if (!IsIgnoringSystemIndexes())
@@ -1741,7 +1707,7 @@ DefaultBuild(Relation heapRelation,
TupleDesc heapDescriptor;
Datum datum[INDEX_MAX_KEYS];
char nullv[INDEX_MAX_KEYS];
long reltuples,
double reltuples,
indtuples;
Node *predicate = indexInfo->ii_Predicate;
@@ -1796,7 +1762,7 @@ DefaultBuild(Relation heapRelation,
0, /* number of keys */
(ScanKey) NULL); /* scan key */
reltuples = indtuples = 0;
reltuples = indtuples = 0.0;
/*
* for each tuple in the base relation, we create an index tuple and
@@ -1808,7 +1774,7 @@ DefaultBuild(Relation heapRelation,
{
MemoryContextReset(econtext->ecxt_per_tuple_memory);
reltuples++;
reltuples += 1.0;
#ifndef OMIT_PARTIAL_INDEX
@@ -1821,7 +1787,7 @@ DefaultBuild(Relation heapRelation,
slot->val = heapTuple;
if (ExecQual((List *) oldPred, econtext, false))
{
indtuples++;
indtuples += 1.0;
continue;
}
}
@@ -1838,7 +1804,7 @@ DefaultBuild(Relation heapRelation,
}
#endif /* OMIT_PARTIAL_INDEX */
indtuples++;
indtuples += 1.0;
/*
* FormIndexDatum fills in its datum and null parameters with