Postgres Performance Issue - Mailing list pgsql-general

Hi,

We're trying to figure out why we're getting poor query performance on a particular database running on a 64 bit
Solarisbox.  The info for the poor database is: 

Red Hat Enterprise Linux AS release 4 (Nahant Update 2) Linux vl-sfv40z-001 2.6.9-22.0.2.ELsmp #1 SMP Thu Jan 5
17:11:56EST 2006 x86_64 x86_64 x86_64 GNU/Linux 

16Gb ram.

Postgres version 8.1.2

Database size is about 7 Gigs.

Live lines in config:
----------------------------------------
max_connections = 500
shared_buffers = 21760
work_mem = 2048
max_fsm_pages = 50000
checkpoint_segments = 125
effective_cache_size = 262144  # =2GB typically 8KB each
redirect_stderr = on                    # Enable capturing of stderr into log
log_directory = '/var/log/pglogs'
log_truncate_on_rotation = on           # If on, any existing log file of the same
log_rotation_size = 10240
log_min_duration_statement = 4000
stats_command_string = on
lc_messages = 'en_US.UTF-8'                     # locale for system error message
lc_monetary = 'en_US.UTF-8'                     # locale for monetary formatting
lc_numeric = 'en_US.UTF-8'                      # locale for number formatting
lc_time = 'en_US.UTF-8'                         # locale for time formatting

We've already ruled out an I/O issue.  The disk is running FAST.

We know it's running poorly because when we put a copy of the database on a lesser hardware 32 bit server, it runs TEN
TIMESfaster. 

Here are the relevant issues with the FAST server:

Red Hat Enterprise Linux AS release 4 (Nahant Update 4) Linux vl-filesrv-001 2.6.9-42.0.8.ELsmp #1 SMP Tue Jan 23
13:01:26EST 2007 i686 i686 i386 GNU/Linux 

Dell dual CPU
4GB ram.


Postgres version: 8.2.3

live config lines:

max_connections = 100                   # (change requires restart)
shared_buffers = 24MB                   # min 128kB or max_connections*16kB
max_fsm_pages = 153600          # min max_fsm_relations*16, 6 bytes each
redirect_stderr = on                    # Enable capturing of stderr into log
log_directory = 'pg_log'                # Directory where log files are writtenlog_truncate_on_rotation = on
#If on, any existing log file of the same 
log_rotation_age = 1d                   # Automatic rotation of logfiles will
log_rotation_size = 0                   # Automatic rotation of logfiles will
datestyle = 'iso, mdy'
lc_messages = 'en_US.UTF-8'                     # locale for system error message
lc_monetary = 'en_US.UTF-8'                     # locale for monetary formatting
lc_numeric = 'en_US.UTF-8'                      # locale for number formatting
lc_time = 'en_US.UTF-8'                         # locale for time formatting
--- --- --- ---
I explain the characterization of fast and slow like this:  Slow is taking about ten times longer than fast to execute
thesame query. 

If there's any gotcha here that we're not seeing, please point it out.  I'm flummoxed.