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Editorial Team
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Asked: 2026-05-24T15:59:15+00:00

I’m on this machine: intel core 2 duo e8400 @3GHZ 4GB ram ddr2 php

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I’m on this machine:

intel core 2 duo e8400 @3GHZ
4GB ram ddr2

php 5.3.6
pgsql 9.1

I’m running a php script that takes like 5 minutes on a mac with similar specs.
This php script, essentially, recreate a db importing some data into it.

On this computer it runs in more than 20 minutes.

The weird thing is the use of the CPU from both PHP & POSTGRESQL

 PID  USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND 
 8408 postgres  20   0 2188m  44m  40m D    4  1.1   0:20.71 postgres                                                                                                                                          
 8407 gianps    20   0  380m 225m 6620 S    2  5.7   0:11.78 php


top - 16:08:32 up  3:35,  3 users,  load average: 1.26, 1.15, 0.80
Tasks: 187 total,   1 running, 185 sleeping,   0 stopped,   1 zombie
Cpu(s):  4.8%us,  2.7%sy,  0.2%ni, 87.0%id,  5.1%wa,  0.0%hi,  0.2%si,  0.0%st
Mem:   4056572k total,  2541972k used,  1514600k free,   117772k buffers
Swap:  3905532k total,        0k used,  3905532k free,   902048k cached

I setup the php (both cli and apache) to use as much ram as they need (memory limit -1) and tuned postgres to use:

shared_buffers = 2GB
effective_cache_size = 3072MB

Any suggestion to let this script use more ram & more cpu and run faster?

thanks

update:
after some investigation i found that that setting synchronous commit (in this situation) makes my script 10x faster.

set synchronous_commit to off;

since is not safe to make this option a default, i just switch it to off when needed..
to understand what synchronous commit does documentation

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1 Answer

  1. Editorial Team

    Importing data requires writing it to disk, so the duration of the process is likely given by the performance of the local storage system. If your Mac has a flashy SSD and the other box an IDE disk, the latter may easily be a lot slower. Use iostat to visualize disk throughput on both systems.

    Another big performance factor for inserting/writing data is commit size, try inserting a lot of rows at once and then issue a commit only every few thousand rows. Or use the even faster “COPY FROM STDIN” method (this is proprietary to Postgresql).

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