If your database server is sharing hardware with another use, particularly the common situation where a database-driven application is installed on the same system, you cannot be nearly as aggressive in your tuning as described in the last section. An exact procedure is harder to outline. What you should try to do is use tuning values for the memory-related values on the low side of recommended practice:
- Only dedicate 10 percent of RAM to
shared_buffersat first, even on platforms where more would normally be advised - Set
effective_cache_sizeto 50 percent or less of system RAM, perhaps less if you know your application is going to be using a lot of it - Be very stingy about increases to
work_mem
The other suggestions in the above section should still hold—using larger values for checkpoint_segments and considering the appropriate choice of wal_sync_method, for example, are no different on a shared system than on a dedicated one.
Then, simulate your application...