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Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/postgres-fdw.sgml | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml index 527f4deaaa2..6c943184850 100644 --- a/doc/src/sgml/postgres-fdw.sgml +++ b/doc/src/sgml/postgres-fdw.sgml @@ -326,6 +326,41 @@ OPTIONS (ADD password_required 'false'); frequently updated, the local statistics will soon be obsolete. </para> + <para> + The following option controls how such an <command>ANALYZE</command> + operation behaves: + </para> + + <variablelist> + + <varlistentry> + <term><literal>analyze_sampling</literal> (<type>text</type>)</term> + <listitem> + <para> + This option, which can be specified for a foreign table or a foreign + server, determines if <command>ANALYZE</command> on a foreign table + samples the data on the remote side, or reads and transfers all data + and performs the sampling locally. The supported values + are <literal>off</literal>, <literal>random</literal>, + <literal>system</literal>, <literal>bernoulli</literal> + and <literal>auto</literal>. <literal>off</literal> disables remote + sampling, so all data are transferred and sampled locally. + <literal>random</literal> performs remote sampling using the + <literal>random()</literal> function to choose returned rows, + while <literal>system</literal> and <literal>bernoulli</literal> rely + on the built-in <literal>TABLESAMPLE</literal> methods of those + names. <literal>random</literal> works on all remote server versions, + while <literal>TABLESAMPLE</literal> is supported only since 9.5. + <literal>auto</literal> (the default) picks the recommended sampling + method automatically; currently it means + either <literal>bernoulli</literal> or <literal>random</literal> + depending on the remote server version. + </para> + </listitem> + </varlistentry> + + </variablelist> + </sect3> <sect3> |