</note>

<para>

Since the <literal>intelligent</literal> mode tries to learn separately for

different query types, <filename>aqo</filename> may fail to providepeformance improvements if the types of the queries in the workload are constantly changing. For such dynamic workloads, reset the <filename>aqo</filename> extension to

different query types, <filename>aqo</filename> may fail to provideperformance improvements if the types of the queries in the workload are constantly changing. For such dynamic workloads, reset the <filename>aqo</filename> extension to

the <literal>controlled</literal> mode, or try using the <literal>forced</literal> mode.

</para>

<para>

most frequently used pages. Each page is fixed size (8kb by default). But if we compress page, then

its size will depend on its content. So updated page can require more (or less) space than original page.

So we may not always perform in-place update of the page. Instead of it we have to locate new space for the page and somehow release

old space. There are two mainapporaches of solving this problem:

old space. There are two mainapproaches to solving this problem:

</para>

<variablelist>

<sect2 id="multimaster-limitations">

<title>Limitations</title>

<para>The <filename>multimaster</filename> extension takes care of the database replication in a fully automated way. You can perform write transactions on any node and work with temporary tables on each cluster nodesimultaneosly. However, make sure to take the following replication restrictions into account:</para>

<para>The <filename>multimaster</filename> extension takes care of the database replication in a fully automated way. You can perform write transactions on any node and work with temporary tables on each cluster nodesimultaneously. However, make sure to take the following replication restrictions into account:</para>

<itemizedlist>

<listitem>

<para>

<varlistentry><term><varname>multimaster.max_recovery_lag</varname><indexterm><primary><varname>multimaster.max_recovery_lag</varname></primary></indexterm></term><listitem><para>

Maximal WAL lag

size, in bytes. When a node is disconnected from the cluster, other

nodes copy WALs for all newtrasactions into the replication slot of

nodes copy WALs for all newtransactions into the replication slot of

this node. Upon reaching the

<varname>multimaster.max_recovery_lag</varname> value, the

replication slot for the disconnected node is dropped to avoid

<title>Synopsis</title>

<para>

&productname; uses cost-based optimizer, which utilizes data

statistics, not static rules. The planner (optimizer)esitimates

statistics, not static rules. The planner (optimizer)estimates

costs of each possible execution plans for a SQL statement then

the execution plan with the lowest cost finally be executed. The

planner does its best to select the best execution plan, but

condition. This hint can corrects the number by several methods,

which are absolute value, addition/subtraction and

multiplication. The parameters are the list of objects compose

thetargetted join then operation. The following example shows

thetargeted join then operation. The following example shows

notations to correct the number of the join on a and b by the

four correction methods.

</para>

<title>GUC temporarily setting</title>

<para>

<quote>Set</quote> hint sets GUC parameter values during the

target statement is underplannning. In the following example,

target statement is underplanning. In the following example,

planning for the query is done with random_page_cost is 2.0.

</para>

<programlisting>

<title>Limitations on multiple VALUES lists in FROM

clauses</title>

<para>

Alloccurences of VALUES lists in FROM clauses in a query has

Alloccurrences of VALUES lists in FROM clauses in a query has

the same name <quote>*VALUES*</quote> irrespective of aliases

syntactically given to them or shown in explain descriptions. So

it cannot be hinted at all ifappeares twice or more in a target

it cannot be hinted at all ifappears twice or more in a target

query.

</para>

</sect3>

Hints are effective on any objects with the target name even if

they aren't apparent in the query, specifically objects in views.

For that reason, you should create different views in which

targetted objects have distinct aliases if you want to hint them

targeted objects have distinct aliases if you want to hint them

differently from the first view.

</para>

<para>

<sect3>

<title>Object misspecifications</title>

<para>

Object misspecifications results silentingorance of the hints.

Object misspecifications results silentignorance of the hints.

This kind of error is reported as <quote>not used hints</quote>

in the server log by the samecondtion to syntax errors.

in the server log by the samecondition to syntax errors.

</para>

</sect3>

<sect3>

<para>

ECPG removes comments in queries written as embedded SQLs so

hints cannot be passed form those queries. The only exception is

that EXECUTE command passes given stringunmodifed. Please

that EXECUTE command passes given stringunmodified. Please

consider hint tables for this case.

</para>

</sect3>

<programlisting>

<varname>schedule.max_parallel_workers</varname> = 3

</programlisting>

<para>By default, twobackgound workers for one-time jobs are available. These workers are not included into the <varname>schedule.max_workers</> number. Thus, one-time jobs can run in parallel with the scheduled jobs even if all the <varname>schedule.max_workers</> workers are busy.</para>

<para>By default, twobackground workers for one-time jobs are available. These workers are not included into the <varname>schedule.max_workers</> number. Thus, one-time jobs can run in parallel with the scheduled jobs even if all the <varname>schedule.max_workers</> workers are busy.</para>

</listitem>

<listitem>

<para>

<para>

For previous versions load the script

<filename>$SHAREDIR/contrib/uninstall_pg_repack.sql</filename> into the database

where the erroroccured and then load <filename>$SHAREDIR/contrib/pg_repack.sql</filename>

where the erroroccurred and then load <filename>$SHAREDIR/contrib/pg_repack.sql</filename>

again.

</para>

use of <xref linkend="pgupgrade">, is required for those

wishing to migrate data from any previous major release.</para>

<para>Dump/restore isneccessary when migrating from <productname>PostgreSQL</productname>

<para>Dump/restore isnecessary when migrating from <productname>PostgreSQL</productname>

or <productname>Postgres Pro Standard</productname> edition.</para>

<para>For upgrades from previous releases of <productname>Postgres Pro Standard</productname> or

use of <xref linkend="pgupgrade">, is required for those

wishing to migrate data from any previous major release.</para>

<para>Dump/restore isneccessary when migrating from <productname>PostgreSQL</productname>

<para>Dump/restore isnecessary when migrating from <productname>PostgreSQL</productname>

or <productname>Postgres Pro Standard</productname> edition.</para>

<para>For upgrades from previous releases of <productname>Postgres Pro Standard</productname> or from

<para>

Slow ranking. The positional information is needed for ranking.

<literal>GIN</literal> index doesn't store positions of lexems.

So after index scan we need an additional heap scan toretreive

So after index scan we need an additional heap scan toretrieve

lexems positions.

</para>

</listitem>

</para>

<para>

By supporting the ordering &lt;-&gt; operator the quad_point_ops and kd_point_ops provide

a user with the ability to perform a K-nearest-neighbour search over the indexed point dataset.

a user with the ability to perform a K-nearest-neighbor search over the indexed point dataset.

</para>

</sect1>

from the page start to the start of unallocated space, to the end of

unallocated space, and to the start of the special space.

Next are two 8-byte fields containing epoch, i. e. an offset, for

short (4-byte)transacion IDs in this page. The next 2

short (4-byte)transaction IDs in this page. The next 2

bytes of the page header, <structfield>pd_pagesize_version</structfield>,

store both the page size and a version indicator. Beginning with

<productname>PostgreSQL</productname> 8.3 the version number is 4;