database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-08 11:42:09 +03:00
Code Activity

Increase the default value of default_statistics_target from 10 to 100,

Browse Source 
and its maximum value from 1000 to 10000.  ALTER TABLE SET STATISTICS
similarly now allows a value up to 10000.  Per discussion.
This commit is contained in:
Tom Lane
2008-12-13 19:13:44 +00:00
parent b69bde7749
commit 65e3ea7641
9 changed files with 27 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/commands/analyze.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.128 2008/11/10 00:49:37 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.129 2008/12/13 19:13:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -67,7 +67,7 @@ typedef struct AnlIndexData
/* Default statistics target (GUC parameter) */
int default_statistics_target = 10;
int default_statistics_target = 100;
/* A few variables that don't seem worth passing around as parameters */
static int elevel = -1;
@ -1531,10 +1531,10 @@ std_typanalyze(VacAttrStats *stats)
* error in bin size f, and error probability gamma, the minimum
* random sample size is
* r = 4 * k * ln(2*n/gamma) / f^2
* Taking f = 0.5, gamma = 0.01, n = 1 million rows, we obtain
* Taking f = 0.5, gamma = 0.01, n = 10^6 rows, we obtain
* r = 305.82 * k
* Note that because of the log function, the dependence on n is
* quite weak; even at n = 1 billion, a 300*k sample gives <= 0.59
* quite weak; even at n = 10^12, a 300*k sample gives <= 0.66
* bin size error with probability 0.99. So there's no real need to
* scale for n, which is a good thing because we don't necessarily
* know it at this point.