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Add new files from Oliver and Thomas.
This commit is contained in:
Thomas G. Lockhart
581
doc/src/sgml/ref/set.sgml
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581
doc/src/sgml/ref/set.sgml
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@@ -0,0 +1,581 @@
|
||||
<REFENTRY ID="SQL-SET">
|
||||
<REFMETA>
|
||||
<REFENTRYTITLE>
|
||||
SET
|
||||
</REFENTRYTITLE>
|
||||
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
|
||||
</REFMETA>
|
||||
<REFNAMEDIV>
|
||||
<REFNAME>
|
||||
SET
|
||||
</REFNAME>
|
||||
<REFPURPOSE>
|
||||
Set run-time parameters for session
|
||||
</REFPURPOSE>
|
||||
<REFSYNOPSISDIV>
|
||||
<REFSYNOPSISDIVINFO>
|
||||
<DATE>1998-08-31</DATE>
|
||||
</REFSYNOPSISDIVINFO>
|
||||
<SYNOPSIS>
|
||||
<REPLACEABLE CLASS="PARAMETER">
|
||||
</REPLACEABLE>
|
||||
SET <REPLACEABLE CLASS="PARAMETER">variable</REPLACEABLE> { TO | = } { '<REPLACEABLE CLASS="PARAMETER">value</REPLACEABLE>' | DEFAULT }
|
||||
|
||||
SET TIME ZONE { '<REPLACEABLE CLASS="PARAMETER">timezone</REPLACEABLE>' | LOCAL };
|
||||
</SYNOPSIS>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-SET-1">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-08-31</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Inputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
<REPLACEABLE CLASS="PARAMETER">variable</REPLACEABLE>
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<para>
|
||||
Settable global parameter.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
<REPLACEABLE CLASS="PARAMETER">value</REPLACEABLE>
|
||||
</term>
|
||||
<listitem>
|
||||
<PARA>
|
||||
New value of parameter.
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
The possible variables and allowed values are:
|
||||
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
DateStyle
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
ISO
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
use ISO 8601-style dates and times
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
SQL
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
use Oracle/Ingres-style dates and times
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
Postgres
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
use traditional <productname>Postgres</productname> format
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
European
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
use dd/mm/yyyy for numeric date representations.
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
NonEuropean
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
use mm/dd/yyyy for numeric date representations.
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
German
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
use dd.mm.yyyy for numeric date representations.
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
US
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
same as 'NonEuropean'
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
default
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
restores the default values ('US,Postgres')
|
||||
</varlistentry>
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
Date format initialization my be done by:
|
||||
<simplelist>
|
||||
<member>
|
||||
Setting PGDATESTYLE environment variable.
|
||||
|
||||
<member>
|
||||
Running postmaster using -oe parameter to set
|
||||
dates to the 'European' convention.
|
||||
Note that this affects only the some combinations of date styles; for example
|
||||
the ISO style is not affected by this parameter.
|
||||
<member>
|
||||
Changing variables in
|
||||
<filename>src/backend/utils/init/globals.c</filename>.
|
||||
</simplelist>
|
||||
|
||||
<para>
|
||||
The variables in <filename>globals.c</filename> which can be changed are:
|
||||
<programlisting>
|
||||
bool EuroDates = false
|
||||
true
|
||||
int DateStyle = USE_ISO_DATES
|
||||
USE_POSTGRES_DATES
|
||||
USE_ISO_DATES
|
||||
USE_SQL_DATES
|
||||
USE_GERMAN_DATES
|
||||
</programlisting>
|
||||
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
TIMEZONE
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
The possible values for timezone depends on your operating
|
||||
system. For example on Linux /usr/lib/zoneinfo contains the
|
||||
database of timezones.
|
||||
<para>
|
||||
Here are some valid values for timezone:
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
'PST8PDT'
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
set the timezone for California
|
||||
<varlistentry>
|
||||
<term>
|
||||
'Portugal'
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
set time zone for Portugal.
|
||||
<varlistentry>
|
||||
<term>
|
||||
'Europe/Rome'
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
set time zone for Italy.
|
||||
<varlistentry>
|
||||
<term>
|
||||
DEFAULT
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
set time zone to your local timezone
|
||||
(value of the TZ environment variable).
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
If an invalid time zone is specified, the time zone
|
||||
becomes GMT (on most systems anyway).
|
||||
<para>
|
||||
A frontend which uses libpq may be initialized by setting the PGTZ
|
||||
environment variable.
|
||||
<para>
|
||||
The second syntax shown above, allows one to set the timezone
|
||||
with a syntax similar to SQL92 <command>SET TIME ZONE</command>.
|
||||
The LOCAL keyword is just an alternate form
|
||||
of DEFAULT for SQL92 compatibility.
|
||||
|
||||
</varlistentry>
|
||||
</variablelist>
|
||||
|
||||
There are also several internal or optimization parameters which can be specified
|
||||
by the <command>SET</command> command:
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
COST_HEAP
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Sets the default cost of a heap scan for use by the optimizer.
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
<replaceable class="parameter">float4</replaceable>
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Set the cost of a heap scan to the specified floating point value.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
DEFAULT
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Sets the cost of a heap scan to the default value.
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
The frontend may be initialized by setting the PGCOSTHEAP
|
||||
environment variable.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
COST_INDEX
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Sets the default cost of an index scan for use by the optimizer.
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
<replaceable class="parameter">float4</replaceable>
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Set the cost of an index scan to the specified floating point value.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
DEFAULT
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Sets the cost of an index scan to the default value.
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
The frontend may be initialized by setting the PGCOSTINDEX
|
||||
environment variable.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
GEQO
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Sets the threshold for using the genetic optimizer algorithm.
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
On
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
enables the genetic optimizer algorithm
|
||||
for statements with 8 or more tables.
|
||||
<varlistentry>
|
||||
<term>
|
||||
On=#
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
enables the genetic optimizer algorithm
|
||||
for statements with # or more tables.
|
||||
<varlistentry>
|
||||
<term>
|
||||
Off
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
disables the genetic optimizer algorithm.
|
||||
<varlistentry>
|
||||
<term>
|
||||
DEFAULT
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Equivalent to specifying <command>SET GEQO=On</command>
|
||||
</varlistentry>
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
This algorithm is on by default, which used GEQO for
|
||||
statements of eight or more tables.
|
||||
(See the chapter on GEQO in the Programmer's Guide
|
||||
for more information).
|
||||
|
||||
<para>
|
||||
The frontend may be initialized by setting PGGEQO
|
||||
environment variable.
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
R_PLANS
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Determines whether right-hand plan evaluation is allowed:
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
On
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
enables right-hand evaluation of plans.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
Off
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
disables right-hand evaluation of plans.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
DEFAULT
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Equivalent to specifying <command>SET R_PLANS=Off</command>.
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
It may be useful when joining big relations with
|
||||
small ones. This algorithm is off by default.
|
||||
It's not used by GEQO anyway.
|
||||
<para>
|
||||
The frontend may be initialized by setting the PGRPLANS
|
||||
environment variable.
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
R_PLANS
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Determines whether right-hand plan evaluation is allowed:
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
On
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
enables right-hand evaluation of plans.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
Off
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
disables right-hand evaluation of plans.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
DEFAULT
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Equivalent to specifying <command>SET R_PLANS=Off</command>.
|
||||
</variablelist>
|
||||
|
||||
<para>
|
||||
It may be useful when joining big relations with
|
||||
small ones. This algorithm is off by default.
|
||||
It's not used by GEQO anyway.
|
||||
<para>
|
||||
The frontend may be initialized by setting the PGRPLANS
|
||||
environment variable.
|
||||
|
||||
</VARLISTENTRY>
|
||||
</VARIABLELIST>
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-SET-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-08-31</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Outputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
SET VARIABLE
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
Message returned if successfully.
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
WARN: Bad value for <replaceable class="parameter">variable</replaceable> (<replaceable class="parameter">value</replaceable>)
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
If fails to set variable.
|
||||
</VARLISTENTRY>
|
||||
</VARIABLELIST>
|
||||
|
||||
</REFSECT2>
|
||||
</REFSYNOPSISDIV>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-SET-1">
|
||||
<REFSECT1INFO>
|
||||
<DATE>1998-08-31</DATE>
|
||||
</REFSECT1INFO>
|
||||
<TITLE>
|
||||
Description
|
||||
</TITLE>
|
||||
<PARA>
|
||||
SET will modify configuration parameters for variable during
|
||||
a session.
|
||||
|
||||
<para>
|
||||
Current values can be obtained using SHOW statement, and values
|
||||
can be restored to the defaults using RESET statement.
|
||||
Parameters and values are case-insensitive. Note that the value
|
||||
field is always specified as a string, so is enclosed in
|
||||
single-quotes.
|
||||
<para>
|
||||
SET TIME ZONE changes the session's default time zone offset.
|
||||
A SQL-session always begins with an initial default time zone
|
||||
offset.
|
||||
The SET TIME ZONE statement is used to change the default
|
||||
time zone offset for the current SQL session.
|
||||
|
||||
<REFSECT2 ID="R2-SQL-SET-3">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-08-31</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Notes
|
||||
</TITLE>
|
||||
<PARA>
|
||||
The <command>SET <replaceable class="parameter">variable</replaceable></command>
|
||||
statement is a <productname>Postgres</productname> language extension.
|
||||
|
||||
<para>
|
||||
Refer to SHOW/RESET statements to show/reset variable values.
|
||||
|
||||
</REFSECT2>
|
||||
</REFSECT1>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-SET-2">
|
||||
<TITLE>
|
||||
Usage
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<ProgramListing>
|
||||
--Set the style of date to ISO:
|
||||
--
|
||||
SET DATESTYLE TO 'ISO';
|
||||
</programlisting>
|
||||
<programlisting>
|
||||
--Set GEQO to default:
|
||||
--
|
||||
SET GEQO = DEFAULT;
|
||||
</programlisting>
|
||||
<programlisting>
|
||||
--Turn on right-hand evaluation of plans:
|
||||
--
|
||||
SET R_PLANS TO 'on';
|
||||
</programlisting>
|
||||
<programlisting>
|
||||
--set the timezone for Berkeley, California:
|
||||
SET TIME ZONE 'PST8PDT';
|
||||
|
||||
SELECT CURRENT_TIMESTAMP AS today;
|
||||
|
||||
today
|
||||
----------------------
|
||||
1998-03-31 07:41:21-08
|
||||
</programlisting>
|
||||
<programlisting>
|
||||
--set the timezone for Italy:
|
||||
SET TIME ZONE 'Europe/Rome';
|
||||
|
||||
SELECT CURRENT_TIMESTAMP AS today;
|
||||
|
||||
today
|
||||
----------------------
|
||||
1998-03-31 17:41:31+02
|
||||
</ProgramListing>
|
||||
|
||||
</REFSECT1>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-SET-3">
|
||||
<TITLE>
|
||||
Compatibility
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-SET-4">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
SQL92
|
||||
</TITLE>
|
||||
<PARA>
|
||||
There is no
|
||||
<command>SET <replaceable class="parameter">variable</replaceable></command>
|
||||
in SQL92.
|
||||
|
||||
The SQL92 syntax for SET TIME ZONE is slightly different,
|
||||
allowing only a single integer value for time zone specification:
|
||||
|
||||
<programlisting>
|
||||
SET TIME ZONE { interval_value_expression | LOCAL }
|
||||
</programlisting>
|
||||
|
||||
</REFENTRY>
|
||||
|
||||
<!--
|
||||
<REPLACEABLE CLASS="PARAMETER">
|
||||
</REPLACEABLE>
|
||||
<ReturnValue></ReturnValue>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>•
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
</PARA>
|
||||
</LISTITEM>
|
||||
</VARLISTENTRY>
|
||||
</VARIABLELIST>
|
||||
<PARA>
|
||||
</PARA>
|
||||
-->
|
||||
Reference in New Issue
Block a user