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diff --git a/doc/src/sgml/html/runtime-config-client.html b/doc/src/sgml/html/runtime-config-client.html new file mode 100644 index 0000000..ba1128e --- /dev/null +++ b/doc/src/sgml/html/runtime-config-client.html @@ -0,0 +1,854 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>20.11. Client Connection Defaults</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="runtime-config-autovacuum.html" title="20.10. Automatic Vacuuming" /><link rel="next" href="runtime-config-locks.html" title="20.12. Lock Management" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">20.11. Client Connection Defaults</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="runtime-config-autovacuum.html" title="20.10. Automatic Vacuuming">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="runtime-config.html" title="Chapter 20. Server Configuration">Up</a></td><th width="60%" align="center">Chapter 20. Server Configuration</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="runtime-config-locks.html" title="20.12. Lock Management">Next</a></td></tr></table><hr /></div><div class="sect1" id="RUNTIME-CONFIG-CLIENT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">20.11. Client Connection Defaults</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="runtime-config-client.html#RUNTIME-CONFIG-CLIENT-STATEMENT">20.11.1. Statement Behavior</a></span></dt><dt><span class="sect2"><a href="runtime-config-client.html#RUNTIME-CONFIG-CLIENT-FORMAT">20.11.2. Locale and Formatting</a></span></dt><dt><span class="sect2"><a href="runtime-config-client.html#RUNTIME-CONFIG-CLIENT-PRELOAD">20.11.3. Shared Library Preloading</a></span></dt><dt><span class="sect2"><a href="runtime-config-client.html#RUNTIME-CONFIG-CLIENT-OTHER">20.11.4. Other Defaults</a></span></dt></dl></div><div class="sect2" id="RUNTIME-CONFIG-CLIENT-STATEMENT"><div class="titlepage"><div><div><h3 class="title">20.11.1. Statement Behavior</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt id="GUC-CLIENT-MIN-MESSAGES"><span class="term"><code class="varname">client_min_messages</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.1.1.3" class="indexterm"></a> + </span></dt><dd><p> + Controls which + <a class="link" href="runtime-config-logging.html#RUNTIME-CONFIG-SEVERITY-LEVELS" title="Table 20.2. Message Severity Levels">message levels</a> + are sent to the client. + Valid values are <code class="literal">DEBUG5</code>, + <code class="literal">DEBUG4</code>, <code class="literal">DEBUG3</code>, <code class="literal">DEBUG2</code>, + <code class="literal">DEBUG1</code>, <code class="literal">LOG</code>, <code class="literal">NOTICE</code>, + <code class="literal">WARNING</code>, and <code class="literal">ERROR</code>. + Each level includes all the levels that follow it. The later the level, + the fewer messages are sent. The default is + <code class="literal">NOTICE</code>. Note that <code class="literal">LOG</code> has a different + rank here than in <a class="xref" href="runtime-config-logging.html#GUC-LOG-MIN-MESSAGES">log_min_messages</a>. + </p><p> + <code class="literal">INFO</code> level messages are always sent to the client. + </p></dd><dt id="GUC-SEARCH-PATH"><span class="term"><code class="varname">search_path</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.2.2.2.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.2.1.4" class="indexterm"></a> + </span></dt><dd><p> + This variable specifies the order in which schemas are searched + when an object (table, data type, function, etc.) is referenced by a + simple name with no schema specified. When there are objects of + identical names in different schemas, the one found first + in the search path is used. An object that is not in any of the + schemas in the search path can only be referenced by specifying + its containing schema with a qualified (dotted) name. + </p><p> + The value for <code class="varname">search_path</code> must be a comma-separated + list of schema names. Any name that is not an existing schema, or is + a schema for which the user does not have <code class="literal">USAGE</code> + permission, is silently ignored. + </p><p> + If one of the list items is the special name + <code class="literal">$user</code>, then the schema having the name returned by + <code class="function">CURRENT_USER</code> is substituted, if there is such a schema + and the user has <code class="literal">USAGE</code> permission for it. + (If not, <code class="literal">$user</code> is ignored.) + </p><p> + The system catalog schema, <code class="literal">pg_catalog</code>, is always + searched, whether it is mentioned in the path or not. If it is + mentioned in the path then it will be searched in the specified + order. If <code class="literal">pg_catalog</code> is not in the path then it will + be searched <span class="emphasis"><em>before</em></span> searching any of the path items. + </p><p> + Likewise, the current session's temporary-table schema, + <code class="literal">pg_temp_<em class="replaceable"><code>nnn</code></em></code>, is always searched if it + exists. It can be explicitly listed in the path by using the + alias <code class="literal">pg_temp</code><a id="id-1.6.7.14.2.2.2.2.5.3" class="indexterm"></a>. If it is not listed in the path then + it is searched first (even before <code class="literal">pg_catalog</code>). However, + the temporary schema is only searched for relation (table, view, + sequence, etc.) and data type names. It is never searched for + function or operator names. + </p><p> + When objects are created without specifying a particular target + schema, they will be placed in the first valid schema named in + <code class="varname">search_path</code>. An error is reported if the search + path is empty. + </p><p> + The default value for this parameter is + <code class="literal">"$user", public</code>. + This setting supports shared use of a database (where no users + have private schemas, and all share use of <code class="literal">public</code>), + private per-user schemas, and combinations of these. Other + effects can be obtained by altering the default search path + setting, either globally or per-user. + </p><p> + For more information on schema handling, see + <a class="xref" href="ddl-schemas.html" title="5.9. Schemas">Section 5.9</a>. In particular, the default + configuration is suitable only when the database has a single user or + a few mutually-trusting users. + </p><p> + The current effective value of the search path can be examined + via the <acronym class="acronym">SQL</acronym> function + <code class="function">current_schemas</code> + (see <a class="xref" href="functions-info.html" title="9.26. System Information Functions and Operators">Section 9.26</a>). + This is not quite the same as + examining the value of <code class="varname">search_path</code>, since + <code class="function">current_schemas</code> shows how the items + appearing in <code class="varname">search_path</code> were resolved. + </p></dd><dt id="GUC-ROW-SECURITY"><span class="term"><code class="varname">row_security</code> (<code class="type">boolean</code>) + <a id="id-1.6.7.14.2.2.3.1.3" class="indexterm"></a> + </span></dt><dd><p> + This variable controls whether to raise an error in lieu of applying a + row security policy. When set to <code class="literal">on</code>, policies apply + normally. When set to <code class="literal">off</code>, queries fail which would + otherwise apply at least one policy. The default is <code class="literal">on</code>. + Change to <code class="literal">off</code> where limited row visibility could cause + incorrect results; for example, <span class="application">pg_dump</span> makes that + change by default. This variable has no effect on roles which bypass + every row security policy, to wit, superusers and roles with + the <code class="literal">BYPASSRLS</code> attribute. + </p><p> + For more information on row security policies, + see <a class="xref" href="sql-createpolicy.html" title="CREATE POLICY"><span class="refentrytitle">CREATE POLICY</span></a>. + </p></dd><dt id="GUC-DEFAULT-TABLE-ACCESS-METHOD"><span class="term"><code class="varname">default_table_access_method</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.2.2.4.1.3" class="indexterm"></a> + </span></dt><dd><p> + This parameter specifies the default table access method to use when + creating tables or materialized views if the <code class="command">CREATE</code> + command does not explicitly specify an access method, or when + <code class="command">SELECT ... INTO</code> is used, which does not allow + specifying a table access method. The default is <code class="literal">heap</code>. + </p></dd><dt id="GUC-DEFAULT-TABLESPACE"><span class="term"><code class="varname">default_tablespace</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.2.2.5.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.5.1.4" class="indexterm"></a> + </span></dt><dd><p> + This variable specifies the default tablespace in which to create + objects (tables and indexes) when a <code class="command">CREATE</code> command does + not explicitly specify a tablespace. + </p><p> + The value is either the name of a tablespace, or an empty string + to specify using the default tablespace of the current database. + If the value does not match the name of any existing tablespace, + <span class="productname">PostgreSQL</span> will automatically use the default + tablespace of the current database. If a nondefault tablespace + is specified, the user must have <code class="literal">CREATE</code> privilege + for it, or creation attempts will fail. + </p><p> + This variable is not used for temporary tables; for them, + <a class="xref" href="runtime-config-client.html#GUC-TEMP-TABLESPACES">temp_tablespaces</a> is consulted instead. + </p><p> + This variable is also not used when creating databases. + By default, a new database inherits its tablespace setting from + the template database it is copied from. + </p><p> + If this parameter is set to a value other than the empty string + when a partitioned table is created, the partitioned table's + tablespace will be set to that value, which will be used as + the default tablespace for partitions created in the future, + even if <code class="varname">default_tablespace</code> has changed since then. + </p><p> + For more information on tablespaces, + see <a class="xref" href="manage-ag-tablespaces.html" title="23.6. Tablespaces">Section 23.6</a>. + </p></dd><dt id="GUC-DEFAULT-TOAST-COMPRESSION"><span class="term"><code class="varname">default_toast_compression</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.6.1.3" class="indexterm"></a> + </span></dt><dd><p> + This variable sets the default + <a class="link" href="storage-toast.html" title="73.2. TOAST">TOAST</a> + compression method for values of compressible columns. + (This can be overridden for individual columns by setting + the <code class="literal">COMPRESSION</code> column option in + <code class="command">CREATE TABLE</code> or + <code class="command">ALTER TABLE</code>.) + The supported compression methods are <code class="literal">pglz</code> and + (if <span class="productname">PostgreSQL</span> was compiled with + <code class="option">--with-lz4</code>) <code class="literal">lz4</code>. + The default is <code class="literal">pglz</code>. + </p></dd><dt id="GUC-TEMP-TABLESPACES"><span class="term"><code class="varname">temp_tablespaces</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.2.2.7.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.7.1.4" class="indexterm"></a> + </span></dt><dd><p> + This variable specifies tablespaces in which to create temporary + objects (temp tables and indexes on temp tables) when a + <code class="command">CREATE</code> command does not explicitly specify a tablespace. + Temporary files for purposes such as sorting large data sets + are also created in these tablespaces. + </p><p> + The value is a list of names of tablespaces. When there is more than + one name in the list, <span class="productname">PostgreSQL</span> chooses a random + member of the list each time a temporary object is to be created; + except that within a transaction, successively created temporary + objects are placed in successive tablespaces from the list. + If the selected element of the list is an empty string, + <span class="productname">PostgreSQL</span> will automatically use the default + tablespace of the current database instead. + </p><p> + When <code class="varname">temp_tablespaces</code> is set interactively, specifying a + nonexistent tablespace is an error, as is specifying a tablespace for + which the user does not have <code class="literal">CREATE</code> privilege. However, + when using a previously set value, nonexistent tablespaces are + ignored, as are tablespaces for which the user lacks + <code class="literal">CREATE</code> privilege. In particular, this rule applies when + using a value set in <code class="filename">postgresql.conf</code>. + </p><p> + The default value is an empty string, which results in all temporary + objects being created in the default tablespace of the current + database. + </p><p> + See also <a class="xref" href="runtime-config-client.html#GUC-DEFAULT-TABLESPACE">default_tablespace</a>. + </p></dd><dt id="GUC-CHECK-FUNCTION-BODIES"><span class="term"><code class="varname">check_function_bodies</code> (<code class="type">boolean</code>) + <a id="id-1.6.7.14.2.2.8.1.3" class="indexterm"></a> + </span></dt><dd><p> + This parameter is normally on. When set to <code class="literal">off</code>, it + disables validation of the routine body string during <a class="xref" href="sql-createfunction.html" title="CREATE FUNCTION"><span class="refentrytitle">CREATE FUNCTION</span></a> and <a class="xref" href="sql-createprocedure.html" title="CREATE PROCEDURE"><span class="refentrytitle">CREATE PROCEDURE</span></a>. Disabling validation avoids side + effects of the validation process, in particular preventing false + positives due to problems such as forward references. + Set this parameter + to <code class="literal">off</code> before loading functions on behalf of other + users; <span class="application">pg_dump</span> does so automatically. + </p></dd><dt id="GUC-DEFAULT-TRANSACTION-ISOLATION"><span class="term"><code class="varname">default_transaction_isolation</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.9.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.9.1.4" class="indexterm"></a> + </span></dt><dd><p> + Each SQL transaction has an isolation level, which can be + either <span class="quote">“<span class="quote">read uncommitted</span>”</span>, <span class="quote">“<span class="quote">read + committed</span>”</span>, <span class="quote">“<span class="quote">repeatable read</span>”</span>, or + <span class="quote">“<span class="quote">serializable</span>”</span>. This parameter controls the + default isolation level of each new transaction. The default + is <span class="quote">“<span class="quote">read committed</span>”</span>. + </p><p> + Consult <a class="xref" href="mvcc.html" title="Chapter 13. Concurrency Control">Chapter 13</a> and <a class="xref" href="sql-set-transaction.html" title="SET TRANSACTION"><span class="refentrytitle">SET TRANSACTION</span></a> for more information. + </p></dd><dt id="GUC-DEFAULT-TRANSACTION-READ-ONLY"><span class="term"><code class="varname">default_transaction_read_only</code> (<code class="type">boolean</code>) + <a id="id-1.6.7.14.2.2.10.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.10.1.4" class="indexterm"></a> + </span></dt><dd><p> + A read-only SQL transaction cannot alter non-temporary tables. + This parameter controls the default read-only status of each new + transaction. The default is <code class="literal">off</code> (read/write). + </p><p> + Consult <a class="xref" href="sql-set-transaction.html" title="SET TRANSACTION"><span class="refentrytitle">SET TRANSACTION</span></a> for more information. + </p></dd><dt id="GUC-DEFAULT-TRANSACTION-DEFERRABLE"><span class="term"><code class="varname">default_transaction_deferrable</code> (<code class="type">boolean</code>) + <a id="id-1.6.7.14.2.2.11.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.11.1.4" class="indexterm"></a> + </span></dt><dd><p> + When running at the <code class="literal">serializable</code> isolation level, + a deferrable read-only SQL transaction may be delayed before + it is allowed to proceed. However, once it begins executing + it does not incur any of the overhead required to ensure + serializability; so serialization code will have no reason to + force it to abort because of concurrent updates, making this + option suitable for long-running read-only transactions. + </p><p> + This parameter controls the default deferrable status of each + new transaction. It currently has no effect on read-write + transactions or those operating at isolation levels lower + than <code class="literal">serializable</code>. The default is <code class="literal">off</code>. + </p><p> + Consult <a class="xref" href="sql-set-transaction.html" title="SET TRANSACTION"><span class="refentrytitle">SET TRANSACTION</span></a> for more information. + </p></dd><dt id="GUC-TRANSACTION-ISOLATION"><span class="term"><code class="varname">transaction_isolation</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.12.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.12.1.4" class="indexterm"></a> + </span></dt><dd><p> + This parameter reflects the current transaction's isolation level. + At the beginning of each transaction, it is set to the current value + of <a class="xref" href="runtime-config-client.html#GUC-DEFAULT-TRANSACTION-ISOLATION">default_transaction_isolation</a>. + Any subsequent attempt to change it is equivalent to a <a class="xref" href="sql-set-transaction.html" title="SET TRANSACTION"><span class="refentrytitle">SET TRANSACTION</span></a> command. + </p></dd><dt id="GUC-TRANSACTION-READ-ONLY"><span class="term"><code class="varname">transaction_read_only</code> (<code class="type">boolean</code>) + <a id="id-1.6.7.14.2.2.13.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.13.1.4" class="indexterm"></a> + </span></dt><dd><p> + This parameter reflects the current transaction's read-only status. + At the beginning of each transaction, it is set to the current value + of <a class="xref" href="runtime-config-client.html#GUC-DEFAULT-TRANSACTION-READ-ONLY">default_transaction_read_only</a>. + Any subsequent attempt to change it is equivalent to a <a class="xref" href="sql-set-transaction.html" title="SET TRANSACTION"><span class="refentrytitle">SET TRANSACTION</span></a> command. + </p></dd><dt id="GUC-TRANSACTION-DEFERRABLE"><span class="term"><code class="varname">transaction_deferrable</code> (<code class="type">boolean</code>) + <a id="id-1.6.7.14.2.2.14.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.14.1.4" class="indexterm"></a> + </span></dt><dd><p> + This parameter reflects the current transaction's deferrability status. + At the beginning of each transaction, it is set to the current value + of <a class="xref" href="runtime-config-client.html#GUC-DEFAULT-TRANSACTION-DEFERRABLE">default_transaction_deferrable</a>. + Any subsequent attempt to change it is equivalent to a <a class="xref" href="sql-set-transaction.html" title="SET TRANSACTION"><span class="refentrytitle">SET TRANSACTION</span></a> command. + </p></dd><dt id="GUC-SESSION-REPLICATION-ROLE"><span class="term"><code class="varname">session_replication_role</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.15.1.3" class="indexterm"></a> + </span></dt><dd><p> + Controls firing of replication-related triggers and rules for the + current session. + Possible values are <code class="literal">origin</code> (the default), + <code class="literal">replica</code> and <code class="literal">local</code>. + Setting this parameter results in discarding any previously cached + query plans. + Only superusers and users with the appropriate <code class="literal">SET</code> + privilege can change this setting. + </p><p> + The intended use of this setting is that logical replication systems + set it to <code class="literal">replica</code> when they are applying replicated + changes. The effect of that will be that triggers and rules (that + have not been altered from their default configuration) will not fire + on the replica. See the <a class="link" href="sql-altertable.html" title="ALTER TABLE"><code class="command">ALTER TABLE</code></a> clauses + <code class="literal">ENABLE TRIGGER</code> and <code class="literal">ENABLE RULE</code> + for more information. + </p><p> + PostgreSQL treats the settings <code class="literal">origin</code> and + <code class="literal">local</code> the same internally. Third-party replication + systems may use these two values for their internal purposes, for + example using <code class="literal">local</code> to designate a session whose + changes should not be replicated. + </p><p> + Since foreign keys are implemented as triggers, setting this parameter + to <code class="literal">replica</code> also disables all foreign key checks, + which can leave data in an inconsistent state if improperly used. + </p></dd><dt id="GUC-STATEMENT-TIMEOUT"><span class="term"><code class="varname">statement_timeout</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.16.1.3" class="indexterm"></a> + </span></dt><dd><p> + Abort any statement that takes more than the specified amount of time. + If <code class="varname">log_min_error_statement</code> is set + to <code class="literal">ERROR</code> or lower, the statement that timed out + will also be logged. + If this value is specified without units, it is taken as milliseconds. + A value of zero (the default) disables the timeout. + </p><p> + The timeout is measured from the time a command arrives at the + server until it is completed by the server. If multiple SQL + statements appear in a single simple-Query message, the timeout + is applied to each statement separately. + (<span class="productname">PostgreSQL</span> versions before 13 usually + treated the timeout as applying to the whole query string.) + In extended query protocol, the timeout starts running when any + query-related message (Parse, Bind, Execute, Describe) arrives, and + it is canceled by completion of an Execute or Sync message. + </p><p> + Setting <code class="varname">statement_timeout</code> in + <code class="filename">postgresql.conf</code> is not recommended because it would + affect all sessions. + </p></dd><dt id="GUC-LOCK-TIMEOUT"><span class="term"><code class="varname">lock_timeout</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.17.1.3" class="indexterm"></a> + </span></dt><dd><p> + Abort any statement that waits longer than the specified amount of + time while attempting to acquire a lock on a table, index, + row, or other database object. The time limit applies separately to + each lock acquisition attempt. The limit applies both to explicit + locking requests (such as <code class="command">LOCK TABLE</code>, or <code class="command">SELECT + FOR UPDATE</code> without <code class="literal">NOWAIT</code>) and to implicitly-acquired + locks. + If this value is specified without units, it is taken as milliseconds. + A value of zero (the default) disables the timeout. + </p><p> + Unlike <code class="varname">statement_timeout</code>, this timeout can only occur + while waiting for locks. Note that if <code class="varname">statement_timeout</code> + is nonzero, it is rather pointless to set <code class="varname">lock_timeout</code> to + the same or larger value, since the statement timeout would always + trigger first. If <code class="varname">log_min_error_statement</code> is set to + <code class="literal">ERROR</code> or lower, the statement that timed out will be + logged. + </p><p> + Setting <code class="varname">lock_timeout</code> in + <code class="filename">postgresql.conf</code> is not recommended because it would + affect all sessions. + </p></dd><dt id="GUC-IDLE-IN-TRANSACTION-SESSION-TIMEOUT"><span class="term"><code class="varname">idle_in_transaction_session_timeout</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.18.1.3" class="indexterm"></a> + </span></dt><dd><p> + Terminate any session that has been idle (that is, waiting for a + client query) within an open transaction for longer than the + specified amount of time. + If this value is specified without units, it is taken as milliseconds. + A value of zero (the default) disables the timeout. + </p><p> + This option can be used to ensure that idle sessions do not hold + locks for an unreasonable amount of time. Even when no significant + locks are held, an open transaction prevents vacuuming away + recently-dead tuples that may be visible only to this transaction; + so remaining idle for a long time can contribute to table bloat. + See <a class="xref" href="routine-vacuuming.html" title="25.1. Routine Vacuuming">Section 25.1</a> for more details. + </p></dd><dt id="GUC-IDLE-SESSION-TIMEOUT"><span class="term"><code class="varname">idle_session_timeout</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.19.1.3" class="indexterm"></a> + </span></dt><dd><p> + Terminate any session that has been idle (that is, waiting for a + client query), but not within an open transaction, for longer than + the specified amount of time. + If this value is specified without units, it is taken as milliseconds. + A value of zero (the default) disables the timeout. + </p><p> + Unlike the case with an open transaction, an idle session without a + transaction imposes no large costs on the server, so there is less + need to enable this timeout + than <code class="varname">idle_in_transaction_session_timeout</code>. + </p><p> + Be wary of enforcing this timeout on connections made through + connection-pooling software or other middleware, as such a layer + may not react well to unexpected connection closure. It may be + helpful to enable this timeout only for interactive sessions, + perhaps by applying it only to particular users. + </p></dd><dt id="GUC-VACUUM-FREEZE-TABLE-AGE"><span class="term"><code class="varname">vacuum_freeze_table_age</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.20.1.3" class="indexterm"></a> + </span></dt><dd><p> + <code class="command">VACUUM</code> performs an aggressive scan if the table's + <code class="structname">pg_class</code>.<code class="structfield">relfrozenxid</code> field has reached + the age specified by this setting. An aggressive scan differs from + a regular <code class="command">VACUUM</code> in that it visits every page that might + contain unfrozen XIDs or MXIDs, not just those that might contain dead + tuples. The default is 150 million transactions. Although users can + set this value anywhere from zero to two billion, <code class="command">VACUUM</code> + will silently limit the effective value to 95% of + <a class="xref" href="runtime-config-autovacuum.html#GUC-AUTOVACUUM-FREEZE-MAX-AGE">autovacuum_freeze_max_age</a>, so that a + periodic manual <code class="command">VACUUM</code> has a chance to run before an + anti-wraparound autovacuum is launched for the table. For more + information see + <a class="xref" href="routine-vacuuming.html#VACUUM-FOR-WRAPAROUND" title="25.1.5. Preventing Transaction ID Wraparound Failures">Section 25.1.5</a>. + </p></dd><dt id="GUC-VACUUM-FREEZE-MIN-AGE"><span class="term"><code class="varname">vacuum_freeze_min_age</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.21.1.3" class="indexterm"></a> + </span></dt><dd><p> + Specifies the cutoff age (in transactions) that <code class="command">VACUUM</code> + should use to decide whether to freeze row versions + while scanning a table. + The default is 50 million transactions. Although + users can set this value anywhere from zero to one billion, + <code class="command">VACUUM</code> will silently limit the effective value to half + the value of <a class="xref" href="runtime-config-autovacuum.html#GUC-AUTOVACUUM-FREEZE-MAX-AGE">autovacuum_freeze_max_age</a>, so + that there is not an unreasonably short time between forced + autovacuums. For more information see <a class="xref" href="routine-vacuuming.html#VACUUM-FOR-WRAPAROUND" title="25.1.5. Preventing Transaction ID Wraparound Failures">Section 25.1.5</a>. + </p></dd><dt id="GUC-VACUUM-FAILSAFE-AGE"><span class="term"><code class="varname">vacuum_failsafe_age</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.22.1.3" class="indexterm"></a> + </span></dt><dd><p> + Specifies the maximum age (in transactions) that a table's + <code class="structname">pg_class</code>.<code class="structfield">relfrozenxid</code> + field can attain before <code class="command">VACUUM</code> takes + extraordinary measures to avoid system-wide transaction ID + wraparound failure. This is <code class="command">VACUUM</code>'s + strategy of last resort. The failsafe typically triggers + when an autovacuum to prevent transaction ID wraparound has + already been running for some time, though it's possible for + the failsafe to trigger during any <code class="command">VACUUM</code>. + </p><p> + When the failsafe is triggered, any cost-based delay that is + in effect will no longer be applied, and further non-essential + maintenance tasks (such as index vacuuming) are bypassed. + </p><p> + The default is 1.6 billion transactions. Although users can + set this value anywhere from zero to 2.1 billion, + <code class="command">VACUUM</code> will silently adjust the effective + value to no less than 105% of <a class="xref" href="runtime-config-autovacuum.html#GUC-AUTOVACUUM-FREEZE-MAX-AGE">autovacuum_freeze_max_age</a>. + </p></dd><dt id="GUC-VACUUM-MULTIXACT-FREEZE-TABLE-AGE"><span class="term"><code class="varname">vacuum_multixact_freeze_table_age</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.23.1.3" class="indexterm"></a> + </span></dt><dd><p> + <code class="command">VACUUM</code> performs an aggressive scan if the table's + <code class="structname">pg_class</code>.<code class="structfield">relminmxid</code> field has reached + the age specified by this setting. An aggressive scan differs from + a regular <code class="command">VACUUM</code> in that it visits every page that might + contain unfrozen XIDs or MXIDs, not just those that might contain dead + tuples. The default is 150 million multixacts. + Although users can set this value anywhere from zero to two billion, + <code class="command">VACUUM</code> will silently limit the effective value to 95% of + <a class="xref" href="runtime-config-autovacuum.html#GUC-AUTOVACUUM-MULTIXACT-FREEZE-MAX-AGE">autovacuum_multixact_freeze_max_age</a>, so that a + periodic manual <code class="command">VACUUM</code> has a chance to run before an + anti-wraparound is launched for the table. + For more information see <a class="xref" href="routine-vacuuming.html#VACUUM-FOR-MULTIXACT-WRAPAROUND" title="25.1.5.1. Multixacts and Wraparound">Section 25.1.5.1</a>. + </p></dd><dt id="GUC-VACUUM-MULTIXACT-FREEZE-MIN-AGE"><span class="term"><code class="varname">vacuum_multixact_freeze_min_age</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.24.1.3" class="indexterm"></a> + </span></dt><dd><p> + Specifies the cutoff age (in multixacts) that <code class="command">VACUUM</code> + should use to decide whether to replace multixact IDs with a newer + transaction ID or multixact ID while scanning a table. The default + is 5 million multixacts. + Although users can set this value anywhere from zero to one billion, + <code class="command">VACUUM</code> will silently limit the effective value to half + the value of <a class="xref" href="runtime-config-autovacuum.html#GUC-AUTOVACUUM-MULTIXACT-FREEZE-MAX-AGE">autovacuum_multixact_freeze_max_age</a>, + so that there is not an unreasonably short time between forced + autovacuums. + For more information see <a class="xref" href="routine-vacuuming.html#VACUUM-FOR-MULTIXACT-WRAPAROUND" title="25.1.5.1. Multixacts and Wraparound">Section 25.1.5.1</a>. + </p></dd><dt id="GUC-VACUUM-MULTIXACT-FAILSAFE-AGE"><span class="term"><code class="varname">vacuum_multixact_failsafe_age</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.25.1.3" class="indexterm"></a> + </span></dt><dd><p> + Specifies the maximum age (in multixacts) that a table's + <code class="structname">pg_class</code>.<code class="structfield">relminmxid</code> + field can attain before <code class="command">VACUUM</code> takes + extraordinary measures to avoid system-wide multixact ID + wraparound failure. This is <code class="command">VACUUM</code>'s + strategy of last resort. The failsafe typically triggers when + an autovacuum to prevent transaction ID wraparound has already + been running for some time, though it's possible for the + failsafe to trigger during any <code class="command">VACUUM</code>. + </p><p> + When the failsafe is triggered, any cost-based delay that is + in effect will no longer be applied, and further non-essential + maintenance tasks (such as index vacuuming) are bypassed. + </p><p> + The default is 1.6 billion multixacts. Although users can set + this value anywhere from zero to 2.1 billion, + <code class="command">VACUUM</code> will silently adjust the effective + value to no less than 105% of <a class="xref" href="runtime-config-autovacuum.html#GUC-AUTOVACUUM-MULTIXACT-FREEZE-MAX-AGE">autovacuum_multixact_freeze_max_age</a>. + </p></dd><dt id="GUC-BYTEA-OUTPUT"><span class="term"><code class="varname">bytea_output</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.26.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the output format for values of type <code class="type">bytea</code>. + Valid values are <code class="literal">hex</code> (the default) + and <code class="literal">escape</code> (the traditional PostgreSQL + format). See <a class="xref" href="datatype-binary.html" title="8.4. Binary Data Types">Section 8.4</a> for more + information. The <code class="type">bytea</code> type always + accepts both formats on input, regardless of this setting. + </p></dd><dt id="GUC-XMLBINARY"><span class="term"><code class="varname">xmlbinary</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.27.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets how binary values are to be encoded in XML. This applies + for example when <code class="type">bytea</code> values are converted to + XML by the functions <code class="function">xmlelement</code> or + <code class="function">xmlforest</code>. Possible values are + <code class="literal">base64</code> and <code class="literal">hex</code>, which + are both defined in the XML Schema standard. The default is + <code class="literal">base64</code>. For further information about + XML-related functions, see <a class="xref" href="functions-xml.html" title="9.15. XML Functions">Section 9.15</a>. + </p><p> + The actual choice here is mostly a matter of taste, + constrained only by possible restrictions in client + applications. Both methods support all possible values, + although the hex encoding will be somewhat larger than the + base64 encoding. + </p></dd><dt id="GUC-XMLOPTION"><span class="term"><code class="varname">xmloption</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.2.2.28.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.28.1.4" class="indexterm"></a> + <a id="id-1.6.7.14.2.2.28.1.5" class="indexterm"></a> + </span></dt><dd><p> + Sets whether <code class="literal">DOCUMENT</code> or + <code class="literal">CONTENT</code> is implicit when converting between + XML and character string values. See <a class="xref" href="datatype-xml.html" title="8.13. XML Type">Section 8.13</a> for a description of this. Valid + values are <code class="literal">DOCUMENT</code> and + <code class="literal">CONTENT</code>. The default is + <code class="literal">CONTENT</code>. + </p><p> + According to the SQL standard, the command to set this option is +</p><pre class="synopsis"> +SET XML OPTION { DOCUMENT | CONTENT }; +</pre><p> + This syntax is also available in PostgreSQL. + </p></dd><dt id="GUC-GIN-PENDING-LIST-LIMIT"><span class="term"><code class="varname">gin_pending_list_limit</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.2.2.29.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the maximum size of a GIN index's pending list, which is used + when <code class="literal">fastupdate</code> is enabled. If the list grows + larger than this maximum size, it is cleaned up by moving + the entries in it to the index's main GIN data structure in bulk. + If this value is specified without units, it is taken as kilobytes. + The default is four megabytes (<code class="literal">4MB</code>). This setting + can be overridden for individual GIN indexes by changing + index storage parameters. + See <a class="xref" href="gin-implementation.html#GIN-FAST-UPDATE" title="70.4.1. GIN Fast Update Technique">Section 70.4.1</a> and <a class="xref" href="gin-tips.html" title="70.5. GIN Tips and Tricks">Section 70.5</a> + for more information. + </p></dd></dl></div></div><div class="sect2" id="RUNTIME-CONFIG-CLIENT-FORMAT"><div class="titlepage"><div><div><h3 class="title">20.11.2. Locale and Formatting</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt id="GUC-DATESTYLE"><span class="term"><code class="varname">DateStyle</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.1.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the display format for date and time values, as well as the + rules for interpreting ambiguous date input values. For + historical reasons, this variable contains two independent + components: the output format specification (<code class="literal">ISO</code>, + <code class="literal">Postgres</code>, <code class="literal">SQL</code>, or <code class="literal">German</code>) + and the input/output specification for year/month/day ordering + (<code class="literal">DMY</code>, <code class="literal">MDY</code>, or <code class="literal">YMD</code>). These + can be set separately or together. The keywords <code class="literal">Euro</code> + and <code class="literal">European</code> are synonyms for <code class="literal">DMY</code>; the + keywords <code class="literal">US</code>, <code class="literal">NonEuro</code>, and + <code class="literal">NonEuropean</code> are synonyms for <code class="literal">MDY</code>. See + <a class="xref" href="datatype-datetime.html" title="8.5. Date/Time Types">Section 8.5</a> for more information. The + built-in default is <code class="literal">ISO, MDY</code>, but + <span class="application">initdb</span> will initialize the + configuration file with a setting that corresponds to the + behavior of the chosen <code class="varname">lc_time</code> locale. + </p></dd><dt id="GUC-INTERVALSTYLE"><span class="term"><code class="varname">IntervalStyle</code> (<code class="type">enum</code>) + <a id="id-1.6.7.14.3.2.2.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the display format for interval values. + The value <code class="literal">sql_standard</code> will produce + output matching <acronym class="acronym">SQL</acronym> standard interval literals. + The value <code class="literal">postgres</code> (which is the default) will produce + output matching <span class="productname">PostgreSQL</span> releases prior to 8.4 + when the <a class="xref" href="runtime-config-client.html#GUC-DATESTYLE">DateStyle</a> + parameter was set to <code class="literal">ISO</code>. + The value <code class="literal">postgres_verbose</code> will produce output + matching <span class="productname">PostgreSQL</span> releases prior to 8.4 + when the <code class="varname">DateStyle</code> + parameter was set to non-<code class="literal">ISO</code> output. + The value <code class="literal">iso_8601</code> will produce output matching the time + interval <span class="quote">“<span class="quote">format with designators</span>”</span> defined in section + 4.4.3.2 of ISO 8601. + </p><p> + The <code class="varname">IntervalStyle</code> parameter also affects the + interpretation of ambiguous interval input. See + <a class="xref" href="datatype-datetime.html#DATATYPE-INTERVAL-INPUT" title="8.5.4. Interval Input">Section 8.5.4</a> for more information. + </p></dd><dt id="GUC-TIMEZONE"><span class="term"><code class="varname">TimeZone</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.3.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.3.2.3.1.4" class="indexterm"></a> + </span></dt><dd><p> + Sets the time zone for displaying and interpreting time stamps. + The built-in default is <code class="literal">GMT</code>, but that is typically + overridden in <code class="filename">postgresql.conf</code>; <span class="application">initdb</span> + will install a setting there corresponding to its system environment. + See <a class="xref" href="datatype-datetime.html#DATATYPE-TIMEZONES" title="8.5.3. Time Zones">Section 8.5.3</a> for more information. + </p></dd><dt id="GUC-TIMEZONE-ABBREVIATIONS"><span class="term"><code class="varname">timezone_abbreviations</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.4.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.3.2.4.1.4" class="indexterm"></a> + </span></dt><dd><p> + Sets the collection of time zone abbreviations that will be accepted + by the server for datetime input. The default is <code class="literal">'Default'</code>, + which is a collection that works in most of the world; there are + also <code class="literal">'Australia'</code> and <code class="literal">'India'</code>, + and other collections can be defined for a particular installation. + See <a class="xref" href="datetime-config-files.html" title="B.4. Date/Time Configuration Files">Section B.4</a> for more information. + </p></dd><dt id="GUC-EXTRA-FLOAT-DIGITS"><span class="term"><code class="varname">extra_float_digits</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.3.2.5.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.3.2.5.1.4" class="indexterm"></a> + <a id="id-1.6.7.14.3.2.5.1.5" class="indexterm"></a> + </span></dt><dd><p> + This parameter adjusts the number of digits used for textual output of + floating-point values, including <code class="type">float4</code>, <code class="type">float8</code>, + and geometric data types. + </p><p> + If the value is 1 (the default) or above, float values are output in + shortest-precise format; see <a class="xref" href="datatype-numeric.html#DATATYPE-FLOAT" title="8.1.3. Floating-Point Types">Section 8.1.3</a>. The + actual number of digits generated depends only on the value being + output, not on the value of this parameter. At most 17 digits are + required for <code class="type">float8</code> values, and 9 for <code class="type">float4</code> + values. This format is both fast and precise, preserving the original + binary float value exactly when correctly read. For historical + compatibility, values up to 3 are permitted. + </p><p> + If the value is zero or negative, then the output is rounded to a + given decimal precision. The precision used is the standard number of + digits for the type (<code class="literal">FLT_DIG</code> + or <code class="literal">DBL_DIG</code> as appropriate) reduced according to the + value of this parameter. (For example, specifying -1 will cause + <code class="type">float4</code> values to be output rounded to 5 significant + digits, and <code class="type">float8</code> values + rounded to 14 digits.) This format is slower and does not preserve all + the bits of the binary float value, but may be more human-readable. + </p><div class="note"><h3 class="title">Note</h3><p> + The meaning of this parameter, and its default value, changed + in <span class="productname">PostgreSQL</span> 12; + see <a class="xref" href="datatype-numeric.html#DATATYPE-FLOAT" title="8.1.3. Floating-Point Types">Section 8.1.3</a> for further discussion. + </p></div></dd><dt id="GUC-CLIENT-ENCODING"><span class="term"><code class="varname">client_encoding</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.6.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.3.2.6.1.4" class="indexterm"></a> + </span></dt><dd><p> + Sets the client-side encoding (character set). + The default is to use the database encoding. + The character sets supported by the <span class="productname">PostgreSQL</span> + server are described in <a class="xref" href="multibyte.html#MULTIBYTE-CHARSET-SUPPORTED" title="24.3.1. Supported Character Sets">Section 24.3.1</a>. + </p></dd><dt id="GUC-LC-MESSAGES"><span class="term"><code class="varname">lc_messages</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.7.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the language in which messages are displayed. Acceptable + values are system-dependent; see <a class="xref" href="locale.html" title="24.1. Locale Support">Section 24.1</a> for + more information. If this variable is set to the empty string + (which is the default) then the value is inherited from the + execution environment of the server in a system-dependent way. + </p><p> + On some systems, this locale category does not exist. Setting + this variable will still work, but there will be no effect. + Also, there is a chance that no translated messages for the + desired language exist. In that case you will continue to see + the English messages. + </p><p> + Only superusers and users with the appropriate <code class="literal">SET</code> + privilege can change this setting. + </p></dd><dt id="GUC-LC-MONETARY"><span class="term"><code class="varname">lc_monetary</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.8.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the locale to use for formatting monetary amounts, for + example with the <code class="function">to_char</code> family of + functions. Acceptable values are system-dependent; see <a class="xref" href="locale.html" title="24.1. Locale Support">Section 24.1</a> for more information. If this variable is + set to the empty string (which is the default) then the value + is inherited from the execution environment of the server in a + system-dependent way. + </p></dd><dt id="GUC-LC-NUMERIC"><span class="term"><code class="varname">lc_numeric</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.9.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the locale to use for formatting numbers, for example + with the <code class="function">to_char</code> family of + functions. Acceptable values are system-dependent; see <a class="xref" href="locale.html" title="24.1. Locale Support">Section 24.1</a> for more information. If this variable is + set to the empty string (which is the default) then the value + is inherited from the execution environment of the server in a + system-dependent way. + </p></dd><dt id="GUC-LC-TIME"><span class="term"><code class="varname">lc_time</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.10.1.3" class="indexterm"></a> + </span></dt><dd><p> + Sets the locale to use for formatting dates and times, for example + with the <code class="function">to_char</code> family of + functions. Acceptable values are system-dependent; see <a class="xref" href="locale.html" title="24.1. Locale Support">Section 24.1</a> for more information. If this variable is + set to the empty string (which is the default) then the value + is inherited from the execution environment of the server in a + system-dependent way. + </p></dd><dt id="GUC-DEFAULT-TEXT-SEARCH-CONFIG"><span class="term"><code class="varname">default_text_search_config</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.3.2.11.1.3" class="indexterm"></a> + </span></dt><dd><p> + Selects the text search configuration that is used by those variants + of the text search functions that do not have an explicit argument + specifying the configuration. + See <a class="xref" href="textsearch.html" title="Chapter 12. Full Text Search">Chapter 12</a> for further information. + The built-in default is <code class="literal">pg_catalog.simple</code>, but + <span class="application">initdb</span> will initialize the + configuration file with a setting that corresponds to the + chosen <code class="varname">lc_ctype</code> locale, if a configuration + matching that locale can be identified. + </p></dd></dl></div></div><div class="sect2" id="RUNTIME-CONFIG-CLIENT-PRELOAD"><div class="titlepage"><div><div><h3 class="title">20.11.3. Shared Library Preloading</h3></div></div></div><p> + Several settings are available for preloading shared libraries into the + server, in order to load additional functionality or achieve performance + benefits. For example, a setting of + <code class="literal">'$libdir/mylib'</code> would cause + <code class="literal">mylib.so</code> (or on some platforms, + <code class="literal">mylib.sl</code>) to be preloaded from the installation's standard + library directory. The differences between the settings are when they + take effect and what privileges are required to change them. + </p><p> + <span class="productname">PostgreSQL</span> procedural language libraries can + be preloaded in this way, typically by using the + syntax <code class="literal">'$libdir/plXXX'</code> where + <code class="literal">XXX</code> is <code class="literal">pgsql</code>, <code class="literal">perl</code>, + <code class="literal">tcl</code>, or <code class="literal">python</code>. + </p><p> + Only shared libraries specifically intended to be used with PostgreSQL + can be loaded this way. Every PostgreSQL-supported library has + a <span class="quote">“<span class="quote">magic block</span>”</span> that is checked to guarantee compatibility. For + this reason, non-PostgreSQL libraries cannot be loaded in this way. You + might be able to use operating-system facilities such + as <code class="envar">LD_PRELOAD</code> for that. + </p><p> + In general, refer to the documentation of a specific module for the + recommended way to load that module. + </p><div class="variablelist"><dl class="variablelist"><dt id="GUC-LOCAL-PRELOAD-LIBRARIES"><span class="term"><code class="varname">local_preload_libraries</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.4.6.1.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.4.6.1.1.4" class="indexterm"></a> + </span></dt><dd><p> + This variable specifies one or more shared libraries that are to be + preloaded at connection start. + It contains a comma-separated list of library names, where each name + is interpreted as for the <a class="link" href="sql-load.html" title="LOAD"><code class="command">LOAD</code></a> command. + Whitespace between entries is ignored; surround a library name with + double quotes if you need to include whitespace or commas in the name. + The parameter value only takes effect at the start of the connection. + Subsequent changes have no effect. If a specified library is not + found, the connection attempt will fail. + </p><p> + This option can be set by any user. Because of that, the libraries + that can be loaded are restricted to those appearing in the + <code class="filename">plugins</code> subdirectory of the installation's + standard library directory. (It is the database administrator's + responsibility to ensure that only <span class="quote">“<span class="quote">safe</span>”</span> libraries + are installed there.) Entries in <code class="varname">local_preload_libraries</code> + can specify this directory explicitly, for example + <code class="literal">$libdir/plugins/mylib</code>, or just specify + the library name — <code class="literal">mylib</code> would have + the same effect as <code class="literal">$libdir/plugins/mylib</code>. + </p><p> + The intent of this feature is to allow unprivileged users to load + debugging or performance-measurement libraries into specific sessions + without requiring an explicit <code class="command">LOAD</code> command. To that end, + it would be typical to set this parameter using + the <code class="envar">PGOPTIONS</code> environment variable on the client or by + using + <code class="command">ALTER ROLE SET</code>. + </p><p> + However, unless a module is specifically designed to be used in this way by + non-superusers, this is usually not the right setting to use. Look + at <a class="xref" href="runtime-config-client.html#GUC-SESSION-PRELOAD-LIBRARIES">session_preload_libraries</a> instead. + </p></dd><dt id="GUC-SESSION-PRELOAD-LIBRARIES"><span class="term"><code class="varname">session_preload_libraries</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.4.6.2.1.3" class="indexterm"></a> + </span></dt><dd><p> + This variable specifies one or more shared libraries that are to be + preloaded at connection start. + It contains a comma-separated list of library names, where each name + is interpreted as for the <a class="link" href="sql-load.html" title="LOAD"><code class="command">LOAD</code></a> command. + Whitespace between entries is ignored; surround a library name with + double quotes if you need to include whitespace or commas in the name. + The parameter value only takes effect at the start of the connection. + Subsequent changes have no effect. If a specified library is not + found, the connection attempt will fail. + Only superusers and users with the appropriate <code class="literal">SET</code> + privilege can change this setting. + </p><p> + The intent of this feature is to allow debugging or + performance-measurement libraries to be loaded into specific sessions + without an explicit + <code class="command">LOAD</code> command being given. For + example, <a class="xref" href="auto-explain.html" title="F.4. auto_explain">auto_explain</a> could be enabled for all + sessions under a given user name by setting this parameter + with <code class="command">ALTER ROLE SET</code>. Also, this parameter can be changed + without restarting the server (but changes only take effect when a new + session is started), so it is easier to add new modules this way, even + if they should apply to all sessions. + </p><p> + Unlike <a class="xref" href="runtime-config-client.html#GUC-SHARED-PRELOAD-LIBRARIES">shared_preload_libraries</a>, there is no large + performance advantage to loading a library at session start rather than + when it is first used. There is some advantage, however, when + connection pooling is used. + </p></dd><dt id="GUC-SHARED-PRELOAD-LIBRARIES"><span class="term"><code class="varname">shared_preload_libraries</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.4.6.3.1.3" class="indexterm"></a> + </span></dt><dd><p> + This variable specifies one or more shared libraries to be preloaded at + server start. + It contains a comma-separated list of library names, where each name + is interpreted as for the <a class="link" href="sql-load.html" title="LOAD"><code class="command">LOAD</code></a> command. + Whitespace between entries is ignored; surround a library name with + double quotes if you need to include whitespace or commas in the name. + This parameter can only be set at server start. If a specified + library is not found, the server will fail to start. + </p><p> + Some libraries need to perform certain operations that can only take + place at postmaster start, such as allocating shared memory, reserving + light-weight locks, or starting background workers. Those libraries + must be loaded at server start through this parameter. See the + documentation of each library for details. + </p><p> + Other libraries can also be preloaded. By preloading a shared library, + the library startup time is avoided when the library is first used. + However, the time to start each new server process might increase + slightly, even if that process never uses the library. So this + parameter is recommended only for libraries that will be used in most + sessions. Also, changing this parameter requires a server restart, so + this is not the right setting to use for short-term debugging tasks, + say. Use <a class="xref" href="runtime-config-client.html#GUC-SESSION-PRELOAD-LIBRARIES">session_preload_libraries</a> for that + instead. + </p><div class="note"><h3 class="title">Note</h3><p> + On Windows hosts, preloading a library at server start will not reduce + the time required to start each new server process; each server process + will re-load all preload libraries. However, <code class="varname">shared_preload_libraries + </code> is still useful on Windows hosts for libraries that need to + perform operations at postmaster start time. + </p></div></dd><dt id="GUC-JIT-PROVIDER"><span class="term"><code class="varname">jit_provider</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.4.6.4.1.3" class="indexterm"></a> + </span></dt><dd><p> + This variable is the name of the JIT provider library to be used + (see <a class="xref" href="jit-extensibility.html#JIT-PLUGGABLE" title="32.4.2. Pluggable JIT Providers">Section 32.4.2</a>). + The default is <code class="literal">llvmjit</code>. + This parameter can only be set at server start. + </p><p> + If set to a non-existent library, <acronym class="acronym">JIT</acronym> will not be + available, but no error will be raised. This allows JIT support to be + installed separately from the main + <span class="productname">PostgreSQL</span> package. + </p></dd></dl></div></div><div class="sect2" id="RUNTIME-CONFIG-CLIENT-OTHER"><div class="titlepage"><div><div><h3 class="title">20.11.4. Other Defaults</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt id="GUC-DYNAMIC-LIBRARY-PATH"><span class="term"><code class="varname">dynamic_library_path</code> (<code class="type">string</code>) + <a id="id-1.6.7.14.5.2.1.1.3" class="indexterm"></a> + <a id="id-1.6.7.14.5.2.1.1.4" class="indexterm"></a> + </span></dt><dd><p> + If a dynamically loadable module needs to be opened and the + file name specified in the <code class="command">CREATE FUNCTION</code> or + <code class="command">LOAD</code> command + does not have a directory component (i.e., the + name does not contain a slash), the system will search this + path for the required file. + </p><p> + The value for <code class="varname">dynamic_library_path</code> must be a + list of absolute directory paths separated by colons (or semi-colons + on Windows). If a list element starts + with the special string <code class="literal">$libdir</code>, the + compiled-in <span class="productname">PostgreSQL</span> package + library directory is substituted for <code class="literal">$libdir</code>; this + is where the modules provided by the standard + <span class="productname">PostgreSQL</span> distribution are installed. + (Use <code class="literal">pg_config --pkglibdir</code> to find out the name of + this directory.) For example: +</p><pre class="programlisting"> +dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' +</pre><p> + or, in a Windows environment: +</p><pre class="programlisting"> +dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' +</pre><p> + </p><p> + The default value for this parameter is + <code class="literal">'$libdir'</code>. If the value is set to an empty + string, the automatic path search is turned off. + </p><p> + This parameter can be changed at run time by superusers and users + with the appropriate <code class="literal">SET</code> privilege, but a + setting done that way will only persist until the end of the + client connection, so this method should be reserved for + development purposes. The recommended way to set this parameter + is in the <code class="filename">postgresql.conf</code> configuration + file. + </p></dd><dt id="GUC-GIN-FUZZY-SEARCH-LIMIT"><span class="term"><code class="varname">gin_fuzzy_search_limit</code> (<code class="type">integer</code>) + <a id="id-1.6.7.14.5.2.2.1.3" class="indexterm"></a> + </span></dt><dd><p> + Soft upper limit of the size of the set returned by GIN index scans. For more + information see <a class="xref" href="gin-tips.html" title="70.5. GIN Tips and Tricks">Section 70.5</a>. + </p></dd></dl></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="runtime-config-autovacuum.html" title="20.10. Automatic Vacuuming">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="runtime-config.html" title="Chapter 20. Server Configuration">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="runtime-config-locks.html" title="20.12. Lock Management">Next</a></td></tr><tr><td width="40%" align="left" valign="top">20.10. Automatic Vacuuming </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 20.12. Lock Management</td></tr></table></div></body></html>
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