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

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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
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12
src/include/utils/lsyscache.h
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@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: lsyscache.h,v 1.30 2001/03/22 04:01:13 momjian Exp $
* $Id: lsyscache.h,v 1.31 2001/05/07 00:43:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -21,8 +21,6 @@ extern AttrNumber get_attnum(Oid relid, char *attname);
extern Oid get_atttype(Oid relid, AttrNumber attnum);
extern bool get_attisset(Oid relid, char *attname);
extern int32 get_atttypmod(Oid relid, AttrNumber attnum);
extern double get_attdispersion(Oid relid, AttrNumber attnum,
double min_estimate);
extern RegProcedure get_opcode(Oid opno);
extern char *get_opname(Oid opno);
extern bool op_mergejoinable(Oid opno, Oid ltype, Oid rtype,
@ -41,6 +39,14 @@ extern bool get_typbyval(Oid typid);
extern void get_typlenbyval(Oid typid, int16 *typlen, bool *typbyval);
extern char get_typstorage(Oid typid);
extern Datum get_typdefault(Oid typid);
extern bool get_attstatsslot(HeapTuple statstuple,
Oid atttype, int32 atttypmod,
int reqkind, Oid reqop,
Datum **values, int *nvalues,
float4 **numbers, int *nnumbers);
extern void free_attstatsslot(Oid atttype,
Datum *values, int nvalues,
float4 *numbers, int nnumbers);
#define TypeIsToastable(typid) (get_typstorage(typid) != 'p')