![]() If this value is specified without units, it is taken as blocks, that is BLCKSZ bytes, typically 8kB. These are session-local buffers used only for access to temporary tables. Sets the maximum amount of memory used for temporary buffers within each database session. Non-default settings are currently supported only on Linux. For more information about usage and support, see Section 19.4.5. Some commonly available page sizes on modern 64 bit server architectures include: 2MB and 1GB (Intel and AMD), 16MB and 16GB (IBM POWER), and 64kB, 2MB, 32MB and 1GB (ARM). This parameter can only be set at server start. When set to 0, the default huge page size on the system will be used. huge_page_size ( integer)Ĭontrols the size of huge pages, when they are enabled with huge_pages. That feature has been known to cause performance degradation with PostgreSQL for some users on some Linux versions, so its use is currently discouraged (unlike explicit use of huge_pages). On Linux, this is called “ transparent huge pages” (THP). Operating systems such as Linux, FreeBSD, and Illumos can also use huge pages (also known as “ super” pages or “ large” pages) automatically for normal memory allocation, without an explicit request from PostgreSQL. Note that this setting only affects the main shared memory area. ![]() When the UAC is enabled, the normal command prompt revokes the user right “ Lock pages in memory” when started. To start the database server on the command prompt as a standalone process, not as a Windows service, the command prompt must be run as an administrator or User Access Control (UAC) must be disabled. You can use Windows Group Policy tool (gpedit.msc) to assign the user right “ Lock pages in memory”. To use them, you need to assign the user right “ Lock pages in memory” to the Windows user account that runs PostgreSQL. Huge pages are known as large pages on Windows. For more details about using huge pages on Linux, see Section 19.4.5. The use of huge pages results in smaller page tables and less CPU time spent on memory management, increasing performance. On Linux, it is only supported when shared_memory_type is set to mmap (the default). The setting is ignored on other systems when set to try. With off, huge pages will not be requested.Īt present, this setting is supported only on Linux and Windows. With on, failure to request huge pages will prevent the server from starting up. With huge_pages set to try, the server will try to request huge pages, but fall back to the default if that fails. Valid values are try (the default), on, and off. huge_pages ( enum)Ĭontrols whether huge pages are requested for the main shared memory area. On systems with less than 1GB of RAM, a smaller percentage of RAM is appropriate, so as to leave adequate space for the operating system. Larger settings for shared_buffers usually require a corresponding increase in max_wal_size, in order to spread out the process of writing large quantities of new or changed data over a longer period of time. There are some workloads where even larger settings for shared_buffers are effective, but because PostgreSQL also relies on the operating system cache, it is unlikely that an allocation of more than 40% of RAM to shared_buffers will work better than a smaller amount. If you have a dedicated database server with 1GB or more of RAM, a reasonable starting value for shared_buffers is 25% of the memory in your system. (Non-default values of BLCKSZ change the minimum value.) This parameter can only be set at server start. However, settings significantly higher than the minimum are usually needed for good performance. ![]() This setting must be at least 128 kilobytes. The default is typically 128 megabytes ( 128MB), but might be less if your kernel settings will not support it (as determined during initdb). Sets the amount of memory the database server uses for shared memory buffers.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |