Re: [PATCHES] Silly bug in pgbench's random number generator
Alexey Klyukin [EMAIL PROTECTED] writes: Gregory Stark wrote: pgbench's random number generator was only generating the first and last value in the specified range half as often as other values in the range. I think this line should be altered this way: return min + (int) (((max - min + 1) * (double) random()) / (MAX_RANDOM_VALUE + 1.0)); eliminating the result of max + 1 in a corner case when random() equals to MAX_RANDOM_VALUE. Yeah, that looks more correct. Applied. regards, tom lane -- Sent via pgsql-patches mailing list (pgsql-patches@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches
Re: [PATCHES] Silly bug in pgbench's random number generator
This has been saved for the 8.4 release: http://momjian.postgresql.org/cgi-bin/pgpatches_hold --- Gregory Stark wrote: pgbench's random number generator was only generating the first and last value in the specified range half as often as other values in the range. Not that it actually matters but it may as well do what it claims. This line has a pretty long and sordid history with various people tweaking it one way and another. cvs diff: Diffing contrib/pgbench Index: contrib/pgbench/pgbench.c === RCS file: /home/stark/src/REPOSITORY/pgsql/contrib/pgbench/pgbench.c,v retrieving revision 1.66 diff -u -r1.66 pgbench.c --- contrib/pgbench/pgbench.c 24 May 2007 18:54:10 - 1.66 +++ contrib/pgbench/pgbench.c 14 Jun 2007 16:22:19 - @@ -191,7 +191,7 @@ static int getrand(int min, int max) { - return min + (int) (((max - min) * (double) random()) / MAX_RANDOM_VALUE + 0.5); + return min + (int) (((max - min + 1) * (double) random()) / MAX_RANDOM_VALUE); } /* call PQexec() and exit() on failure */ -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate -- Bruce Momjian [EMAIL PROTECTED] http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [PATCHES] Silly bug in pgbench's random number generator
Gregory Stark wrote: Uhm, this is a one-line *bug fix*. There wasn't agreement on how it should be fixed, it is a minor bug, and as you said, we should be focusing on the significant outstanding patches submitted before feature freeze. --- Bruce Momjian [EMAIL PROTECTED] writes: This has been saved for the 8.4 release: http://momjian.postgresql.org/cgi-bin/pgpatches_hold --- Gregory Stark wrote: pgbench's random number generator was only generating the first and last value in the specified range half as often as other values in the range. Not that it actually matters but it may as well do what it claims. This line has a pretty long and sordid history with various people tweaking it one way and another. cvs diff: Diffing contrib/pgbench Index: contrib/pgbench/pgbench.c === RCS file: /home/stark/src/REPOSITORY/pgsql/contrib/pgbench/pgbench.c,v retrieving revision 1.66 diff -u -r1.66 pgbench.c --- contrib/pgbench/pgbench.c 24 May 2007 18:54:10 - 1.66 +++ contrib/pgbench/pgbench.c 14 Jun 2007 16:22:19 - @@ -191,7 +191,7 @@ static int getrand(int min, int max) { - return min + (int) (((max - min) * (double) random()) / MAX_RANDOM_VALUE + 0.5); + return min + (int) (((max - min + 1) * (double) random()) / MAX_RANDOM_VALUE); } /* call PQexec() and exit() on failure */ -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate -- Bruce Momjian [EMAIL PROTECTED] http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + -- Gregory Stark EnterpriseDB http://www.enterprisedb.com -- Bruce Momjian [EMAIL PROTECTED] http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [PATCHES] Silly bug in pgbench's random number generator
Uhm, this is a one-line *bug fix*. Bruce Momjian [EMAIL PROTECTED] writes: This has been saved for the 8.4 release: http://momjian.postgresql.org/cgi-bin/pgpatches_hold --- Gregory Stark wrote: pgbench's random number generator was only generating the first and last value in the specified range half as often as other values in the range. Not that it actually matters but it may as well do what it claims. This line has a pretty long and sordid history with various people tweaking it one way and another. cvs diff: Diffing contrib/pgbench Index: contrib/pgbench/pgbench.c === RCS file: /home/stark/src/REPOSITORY/pgsql/contrib/pgbench/pgbench.c,v retrieving revision 1.66 diff -u -r1.66 pgbench.c --- contrib/pgbench/pgbench.c24 May 2007 18:54:10 - 1.66 +++ contrib/pgbench/pgbench.c14 Jun 2007 16:22:19 - @@ -191,7 +191,7 @@ static int getrand(int min, int max) { -return min + (int) (((max - min) * (double) random()) / MAX_RANDOM_VALUE + 0.5); +return min + (int) (((max - min + 1) * (double) random()) / MAX_RANDOM_VALUE); } /* call PQexec() and exit() on failure */ -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate -- Bruce Momjian [EMAIL PROTECTED] http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
[PATCHES] Silly bug in pgbench's random number generator
pgbench's random number generator was only generating the first and last value in the specified range half as often as other values in the range. Not that it actually matters but it may as well do what it claims. This line has a pretty long and sordid history with various people tweaking it one way and another. cvs diff: Diffing contrib/pgbench Index: contrib/pgbench/pgbench.c === RCS file: /home/stark/src/REPOSITORY/pgsql/contrib/pgbench/pgbench.c,v retrieving revision 1.66 diff -u -r1.66 pgbench.c --- contrib/pgbench/pgbench.c 24 May 2007 18:54:10 - 1.66 +++ contrib/pgbench/pgbench.c 14 Jun 2007 16:22:19 - @@ -191,7 +191,7 @@ static int getrand(int min, int max) { - return min + (int) (((max - min) * (double) random()) / MAX_RANDOM_VALUE + 0.5); + return min + (int) (((max - min + 1) * (double) random()) / MAX_RANDOM_VALUE); } /* call PQexec() and exit() on failure */ -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---(end of broadcast)--- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
Re: [PATCHES] Silly bug in pgbench's random number generator
Gregory Stark wrote: pgbench's random number generator was only generating the first and last value in the specified range half as often as other values in the range. Not that it actually matters but it may as well do what it claims. This line has a pretty long and sordid history with various people tweaking it one way and another. cvs diff: Diffing contrib/pgbench Index: contrib/pgbench/pgbench.c === RCS file: /home/stark/src/REPOSITORY/pgsql/contrib/pgbench/pgbench.c,v retrieving revision 1.66 diff -u -r1.66 pgbench.c --- contrib/pgbench/pgbench.c 24 May 2007 18:54:10 - 1.66 +++ contrib/pgbench/pgbench.c 14 Jun 2007 16:22:19 - @@ -191,7 +191,7 @@ static int getrand(int min, int max) { - return min + (int) (((max - min) * (double) random()) / MAX_RANDOM_VALUE + 0.5); + return min + (int) (((max - min + 1) * (double) random()) / MAX_RANDOM_VALUE); } /* call PQexec() and exit() on failure */ I think this line should be altered this way: return min + (int) (((max - min + 1) * (double) random()) / (MAX_RANDOM_VALUE + 1.0)); eliminating the result of max + 1 in a corner case when random() equals to MAX_RANDOM_VALUE. -- Alexey Klyukin http://www.commandprompt.com/ The PostgreSQL Company - Command Prompt, Inc. ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster