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| author | Thomas Munro <tmunro@postgresql.org> | 2020-03-16 12:31:34 +1300 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2020-03-16 17:14:26 +1300 |
| commit | fc34b0d9de27ab5ac2887da00b3892bdabd89e45 (patch) | |
| tree | bfa65c51892f19538b6e7e53633654ddce5eb989 /doc/src/sgml/ref/create_tablespace.sgml | |
| parent | b09ff53667ffc986371ec8ffa372916ad460220d (diff) | |
| download | postgresql-fc34b0d9de27ab5ac2887da00b3892bdabd89e45.tar.gz postgresql-fc34b0d9de27ab5ac2887da00b3892bdabd89e45.zip | |
Introduce a maintenance_io_concurrency setting.
Introduce a GUC and a tablespace option to control I/O prefetching, much
like effective_io_concurrency, but for work that is done on behalf of
many client sessions.
Use the new setting in heapam.c instead of the hard-coded formula
effective_io_concurrency + 10 introduced by commit 558a9165e08. Go with
a default value of 10 for now, because it's a round number pretty close
to the value used for that existing case.
Discussion: https://postgr.es/m/CA%2BhUKGJUw08dPs_3EUcdO6M90GnjofPYrWp4YSLaBkgYwS-AqA%40mail.gmail.com
Diffstat (limited to 'doc/src/sgml/ref/create_tablespace.sgml')
| -rw-r--r-- | doc/src/sgml/ref/create_tablespace.sgml | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/doc/src/sgml/ref/create_tablespace.sgml b/doc/src/sgml/ref/create_tablespace.sgml index c621ec2c6bf..462b8831c27 100644 --- a/doc/src/sgml/ref/create_tablespace.sgml +++ b/doc/src/sgml/ref/create_tablespace.sgml @@ -106,13 +106,16 @@ CREATE TABLESPACE <replaceable class="parameter">tablespace_name</replaceable> <para> A tablespace parameter to be set or reset. Currently, the only available parameters are <varname>seq_page_cost</varname>, - <varname>random_page_cost</varname> and <varname>effective_io_concurrency</varname>. - Setting either value for a particular tablespace will override the + <varname>random_page_cost</varname>, <varname>effective_io_concurrency</varname> + and <varname>maintenance_io_concurrency</varname>. + Setting these values for a particular tablespace will override the planner's usual estimate of the cost of reading pages from tables in - that tablespace, as established by the configuration parameters of the + that tablespace, and the executor's prefetching behavior, as established + by the configuration parameters of the same name (see <xref linkend="guc-seq-page-cost"/>, <xref linkend="guc-random-page-cost"/>, - <xref linkend="guc-effective-io-concurrency"/>). This may be useful if + <xref linkend="guc-effective-io-concurrency"/>, + <xref linkend="guc-maintenance-io-concurrency"/>). This may be useful if one tablespace is located on a disk which is faster or slower than the remainder of the I/O subsystem. </para> |