10.2 Resource Usage Configuration

Path: Port 9443 Appliance Console PostgreSQL Icon > Resource Usage Configuration

Table 10-2 Using the Resource Usage Configuration dialog

Field, Option, or Button	Information and/or Action
Shared Buffers	The percentage of appliance RAM that is shared with PostgreSQL. The PostgreSQL documentation recommends setting this to 25% of system memory: If you have a system with 1GB or more of RAM, a reasonable starting value for shared_buffers is ¼ of the memory in your system. If you have less RAM you'll have to account more carefully for how much RAM the OS is taking up; closer to 15% is more typical there. There are some workloads where even larger settings for shared_buffers are effective, but given the way PostgreSQL also relies on the operating system cache, it's unlikely you'll find using more than 40% of RAM to work better than a smaller amount. For more information, see the PostgreSQL Resource Consumption documentation. From the PostgreSQL tuning documentation
Effective Cache Size	This is the disk cache that is available for a single query. The PostgreSQL documentation recommends setting this to half of total memory: Setting effective_cache_size to ½ of total memory would be a normal conservative setting, and ¾ of memory is a more aggressive but still reasonable amount. You might find a better estimate by looking at your operating system's statistics. See also, effective_cache_size in the PostgreSQL Query Planning section of the PostgreSQL documentation.

Field, Option, or Button

Information and/or Action

Shared Buffers

The percentage of appliance RAM that is shared with PostgreSQL. The PostgreSQL documentation recommends setting this to 25% of system memory:

If you have a system with 1GB or more of RAM, a reasonable starting value for shared_buffers is ¼ of the memory in your system. If you have less RAM you'll have to account more carefully for how much RAM the OS is taking up; closer to 15% is more typical there.

There are some workloads where even larger settings for shared_buffers are effective, but given the way PostgreSQL also relies on the operating system cache, it's unlikely you'll find using more than 40% of RAM to work better than a smaller amount.

For more information, see the PostgreSQL Resource Consumption documentation. From the PostgreSQL tuning documentation

Effective Cache Size

This is the disk cache that is available for a single query. The PostgreSQL documentation recommends setting this to half of total memory:

Setting effective_cache_size to ½ of total memory would be a normal conservative setting, and ¾ of memory is a more aggressive but still reasonable amount.

You might find a better estimate by looking at your operating system's statistics.

See also, effective_cache_size in the PostgreSQL Query Planning section of the PostgreSQL documentation.