20.11. Client Connection Defaults

20.11. Client Connection Defaults
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20.11.1. Statement Behavior
20.11.2. Locale and Formatting
20.11.3. Shared Library Preloading
20.11.4. Other Defaults

20.11.1. Statement Behavior

client_min_messages (enum) + +

+ Controls which + message levels + are sent to the client. + Valid values are DEBUG5, + DEBUG4, DEBUG3, DEBUG2, + DEBUG1, LOG, NOTICE, + WARNING, and ERROR. + Each level includes all the levels that follow it. The later the level, + the fewer messages are sent. The default is + NOTICE. Note that LOG has a different + rank here than in log_min_messages. +

+ INFO level messages are always sent to the client. +

search_path (string) + + +

+ 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. +

+ The value for search_path 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 USAGE + permission, is silently ignored. +

+ If one of the list items is the special name + $user, then the schema having the name returned by + CURRENT_USER is substituted, if there is such a schema + and the user has USAGE permission for it. + (If not, $user is ignored.) +

+ The system catalog schema, pg_catalog, 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 pg_catalog is not in the path then it will + be searched before searching any of the path items. +

+ Likewise, the current session's temporary-table schema, + pg_temp_nnn, is always searched if it + exists. It can be explicitly listed in the path by using the + alias pg_temp. If it is not listed in the path then + it is searched first (even before pg_catalog). 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. +

+ When objects are created without specifying a particular target + schema, they will be placed in the first valid schema named in + search_path. An error is reported if the search + path is empty. +

+ The default value for this parameter is + "$user", public. + This setting supports shared use of a database (where no users + have private schemas, and all share use of public), + 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. +

+ For more information on schema handling, see + Section 5.9. In particular, the default + configuration is suitable only when the database has a single user or + a few mutually-trusting users. +

+ The current effective value of the search path can be examined + via the SQL function + current_schemas + (see Section 9.26). + This is not quite the same as + examining the value of search_path, since + current_schemas shows how the items + appearing in search_path were resolved. +

row_security (boolean) + +

+ This variable controls whether to raise an error in lieu of applying a + row security policy. When set to on, policies apply + normally. When set to off, queries fail which would + otherwise apply at least one policy. The default is on. + Change to off where limited row visibility could cause + incorrect results; for example, pg_dump 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 BYPASSRLS attribute. +

+ For more information on row security policies, + see CREATE POLICY. +

default_table_access_method (string) + +

+ This parameter specifies the default table access method to use when + creating tables or materialized views if the CREATE + command does not explicitly specify an access method, or when + SELECT ... INTO is used, which does not allow + specifying a table access method. The default is heap. +

default_tablespace (string) + + +

+ This variable specifies the default tablespace in which to create + objects (tables and indexes) when a CREATE command does + not explicitly specify a tablespace. +

+ 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, + PostgreSQL will automatically use the default + tablespace of the current database. If a nondefault tablespace + is specified, the user must have CREATE privilege + for it, or creation attempts will fail. +

+ This variable is not used for temporary tables; for them, + temp_tablespaces is consulted instead. +

+ 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. +

+ 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 default_tablespace has changed since then. +

+ For more information on tablespaces, + see Section 23.6. +

default_toast_compression (enum) + +

+ This variable sets the default + TOAST + compression method for values of compressible columns. + (This can be overridden for individual columns by setting + the COMPRESSION column option in + CREATE TABLE or + ALTER TABLE.) + The supported compression methods are pglz and + (if PostgreSQL was compiled with + --with-lz4) lz4. + The default is pglz. +

temp_tablespaces (string) + + +

+ This variable specifies tablespaces in which to create temporary + objects (temp tables and indexes on temp tables) when a + CREATE command does not explicitly specify a tablespace. + Temporary files for purposes such as sorting large data sets + are also created in these tablespaces. +

+ The value is a list of names of tablespaces. When there is more than + one name in the list, PostgreSQL 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, + PostgreSQL will automatically use the default + tablespace of the current database instead. +

+ When temp_tablespaces is set interactively, specifying a + nonexistent tablespace is an error, as is specifying a tablespace for + which the user does not have CREATE privilege. However, + when using a previously set value, nonexistent tablespaces are + ignored, as are tablespaces for which the user lacks + CREATE privilege. In particular, this rule applies when + using a value set in postgresql.conf. +

+ The default value is an empty string, which results in all temporary + objects being created in the default tablespace of the current + database. +

+ See also default_tablespace. +

check_function_bodies (boolean) + +

+ This parameter is normally on. When set to off, it + disables validation of the routine body string during CREATE FUNCTION and CREATE PROCEDURE. 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 off before loading functions on behalf of other + users; pg_dump does so automatically. +

default_transaction_isolation (enum) + + +

+ Each SQL transaction has an isolation level, which can be + either “read uncommitted”, “read + committed”, “repeatable read”, or + “serializable”. This parameter controls the + default isolation level of each new transaction. The default + is “read committed”. +

+ Consult Chapter 13 and SET TRANSACTION for more information. +

default_transaction_read_only (boolean) + + +

+ 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 off (read/write). +

+ Consult SET TRANSACTION for more information. +

default_transaction_deferrable (boolean) + + +

+ When running at the serializable 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. +

+ 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 serializable. The default is off. +

+ Consult SET TRANSACTION for more information. +

transaction_isolation (enum) + + +

+ This parameter reflects the current transaction's isolation level. + At the beginning of each transaction, it is set to the current value + of default_transaction_isolation. + Any subsequent attempt to change it is equivalent to a SET TRANSACTION command. +

transaction_read_only (boolean) + + +

+ This parameter reflects the current transaction's read-only status. + At the beginning of each transaction, it is set to the current value + of default_transaction_read_only. + Any subsequent attempt to change it is equivalent to a SET TRANSACTION command. +

transaction_deferrable (boolean) + + +

+ This parameter reflects the current transaction's deferrability status. + At the beginning of each transaction, it is set to the current value + of default_transaction_deferrable. + Any subsequent attempt to change it is equivalent to a SET TRANSACTION command. +

session_replication_role (enum) + +

+ Controls firing of replication-related triggers and rules for the + current session. + Possible values are origin (the default), + replica and local. + Setting this parameter results in discarding any previously cached + query plans. + Only superusers and users with the appropriate SET + privilege can change this setting. +

+ The intended use of this setting is that logical replication systems + set it to replica 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 ALTER TABLE clauses + ENABLE TRIGGER and ENABLE RULE + for more information. +

+ PostgreSQL treats the settings origin and + local the same internally. Third-party replication + systems may use these two values for their internal purposes, for + example using local to designate a session whose + changes should not be replicated. +

+ Since foreign keys are implemented as triggers, setting this parameter + to replica also disables all foreign key checks, + which can leave data in an inconsistent state if improperly used. +

statement_timeout (integer) + +

+ Abort any statement that takes more than the specified amount of time. + If log_min_error_statement is set + to ERROR 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. +

+ 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. + (PostgreSQL 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. +

+ Setting statement_timeout in + postgresql.conf is not recommended because it would + affect all sessions. +

lock_timeout (integer) + +

+ 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 LOCK TABLE, or SELECT + FOR UPDATE without NOWAIT) 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. +

+ Unlike statement_timeout, this timeout can only occur + while waiting for locks. Note that if statement_timeout + is nonzero, it is rather pointless to set lock_timeout to + the same or larger value, since the statement timeout would always + trigger first. If log_min_error_statement is set to + ERROR or lower, the statement that timed out will be + logged. +

+ Setting lock_timeout in + postgresql.conf is not recommended because it would + affect all sessions. +

idle_in_transaction_session_timeout (integer) + +

+ 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. +

+ 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 Section 25.1 for more details. +

idle_session_timeout (integer) + +

+ 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. +

+ 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 idle_in_transaction_session_timeout. +

+ 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. +

vacuum_freeze_table_age (integer) + +

+ VACUUM performs an aggressive scan if the table's + pg_class.relfrozenxid field has reached + the age specified by this setting. An aggressive scan differs from + a regular VACUUM 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, VACUUM + will silently limit the effective value to 95% of + autovacuum_freeze_max_age, so that a + periodic manual VACUUM has a chance to run before an + anti-wraparound autovacuum is launched for the table. For more + information see + Section 25.1.5. +

vacuum_freeze_min_age (integer) + +

+ Specifies the cutoff age (in transactions) that VACUUM + 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, + VACUUM will silently limit the effective value to half + the value of autovacuum_freeze_max_age, so + that there is not an unreasonably short time between forced + autovacuums. For more information see Section 25.1.5. +

vacuum_failsafe_age (integer) + +

+ Specifies the maximum age (in transactions) that a table's + pg_class.relfrozenxid + field can attain before VACUUM takes + extraordinary measures to avoid system-wide transaction ID + wraparound failure. This is VACUUM'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 VACUUM. +

+ 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. +

+ The default is 1.6 billion transactions. Although users can + set this value anywhere from zero to 2.1 billion, + VACUUM will silently adjust the effective + value to no less than 105% of autovacuum_freeze_max_age. +

vacuum_multixact_freeze_table_age (integer) + +

+ VACUUM performs an aggressive scan if the table's + pg_class.relminmxid field has reached + the age specified by this setting. An aggressive scan differs from + a regular VACUUM 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, + VACUUM will silently limit the effective value to 95% of + autovacuum_multixact_freeze_max_age, so that a + periodic manual VACUUM has a chance to run before an + anti-wraparound is launched for the table. + For more information see Section 25.1.5.1. +

vacuum_multixact_freeze_min_age (integer) + +

+ Specifies the cutoff age (in multixacts) that VACUUM + 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, + VACUUM will silently limit the effective value to half + the value of autovacuum_multixact_freeze_max_age, + so that there is not an unreasonably short time between forced + autovacuums. + For more information see Section 25.1.5.1. +

vacuum_multixact_failsafe_age (integer) + +

+ Specifies the maximum age (in multixacts) that a table's + pg_class.relminmxid + field can attain before VACUUM takes + extraordinary measures to avoid system-wide multixact ID + wraparound failure. This is VACUUM'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 VACUUM. +

+ 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. +

+ The default is 1.6 billion multixacts. Although users can set + this value anywhere from zero to 2.1 billion, + VACUUM will silently adjust the effective + value to no less than 105% of autovacuum_multixact_freeze_max_age. +

bytea_output (enum) + +

+ Sets the output format for values of type bytea. + Valid values are hex (the default) + and escape (the traditional PostgreSQL + format). See Section 8.4 for more + information. The bytea type always + accepts both formats on input, regardless of this setting. +

xmlbinary (enum) + +

+ Sets how binary values are to be encoded in XML. This applies + for example when bytea values are converted to + XML by the functions xmlelement or + xmlforest. Possible values are + base64 and hex, which + are both defined in the XML Schema standard. The default is + base64. For further information about + XML-related functions, see Section 9.15. +

+ 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. +

xmloption (enum) + + + +

+ Sets whether DOCUMENT or + CONTENT is implicit when converting between + XML and character string values. See Section 8.13 for a description of this. Valid + values are DOCUMENT and + CONTENT. The default is + CONTENT. +

+ According to the SQL standard, the command to set this option is +

+SET XML OPTION { DOCUMENT | CONTENT };
+

+ This syntax is also available in PostgreSQL. +

gin_pending_list_limit (integer) + +

+ Sets the maximum size of a GIN index's pending list, which is used + when fastupdate 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 (4MB). This setting + can be overridden for individual GIN indexes by changing + index storage parameters. + See Section 70.4.1 and Section 70.5 + for more information. +

20.11.2. Locale and Formatting

DateStyle (string) + +

+ 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 (ISO, + Postgres, SQL, or German) + and the input/output specification for year/month/day ordering + (DMY, MDY, or YMD). These + can be set separately or together. The keywords Euro + and European are synonyms for DMY; the + keywords US, NonEuro, and + NonEuropean are synonyms for MDY. See + Section 8.5 for more information. The + built-in default is ISO, MDY, but + initdb will initialize the + configuration file with a setting that corresponds to the + behavior of the chosen lc_time locale. +

IntervalStyle (enum) + +

+ Sets the display format for interval values. + The value sql_standard will produce + output matching SQL standard interval literals. + The value postgres (which is the default) will produce + output matching PostgreSQL releases prior to 8.4 + when the DateStyle + parameter was set to ISO. + The value postgres_verbose will produce output + matching PostgreSQL releases prior to 8.4 + when the DateStyle + parameter was set to non-ISO output. + The value iso_8601 will produce output matching the time + interval “format with designators” defined in section + 4.4.3.2 of ISO 8601. +

+ The IntervalStyle parameter also affects the + interpretation of ambiguous interval input. See + Section 8.5.4 for more information. +

TimeZone (string) + + +

+ Sets the time zone for displaying and interpreting time stamps. + The built-in default is GMT, but that is typically + overridden in postgresql.conf; initdb + will install a setting there corresponding to its system environment. + See Section 8.5.3 for more information. +

timezone_abbreviations (string) + + +

+ Sets the collection of time zone abbreviations that will be accepted + by the server for datetime input. The default is 'Default', + which is a collection that works in most of the world; there are + also 'Australia' and 'India', + and other collections can be defined for a particular installation. + See Section B.4 for more information. +

extra_float_digits (integer) + + + +

+ This parameter adjusts the number of digits used for textual output of + floating-point values, including float4, float8, + and geometric data types. +

+ If the value is 1 (the default) or above, float values are output in + shortest-precise format; see Section 8.1.3. 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 float8 values, and 9 for float4 + 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. +

+ 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 (FLT_DIG + or DBL_DIG as appropriate) reduced according to the + value of this parameter. (For example, specifying -1 will cause + float4 values to be output rounded to 5 significant + digits, and float8 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. +

Note

+ The meaning of this parameter, and its default value, changed + in PostgreSQL 12; + see Section 8.1.3 for further discussion. +

client_encoding (string) + + +

+ Sets the client-side encoding (character set). + The default is to use the database encoding. + The character sets supported by the PostgreSQL + server are described in Section 24.3.1. +

lc_messages (string) + +

+ Sets the language in which messages are displayed. Acceptable + values are system-dependent; see Section 24.1 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. +

+ 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. +

+ Only superusers and users with the appropriate SET + privilege can change this setting. +

lc_monetary (string) + +

+ Sets the locale to use for formatting monetary amounts, for + example with the to_char family of + functions. Acceptable values are system-dependent; see Section 24.1 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. +

lc_numeric (string) + +

+ Sets the locale to use for formatting numbers, for example + with the to_char family of + functions. Acceptable values are system-dependent; see Section 24.1 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. +

lc_time (string) + +

+ Sets the locale to use for formatting dates and times, for example + with the to_char family of + functions. Acceptable values are system-dependent; see Section 24.1 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. +

default_text_search_config (string) + +

+ 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 Chapter 12 for further information. + The built-in default is pg_catalog.simple, but + initdb will initialize the + configuration file with a setting that corresponds to the + chosen lc_ctype locale, if a configuration + matching that locale can be identified. +

20.11.3. Shared Library Preloading

+ 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 + '$libdir/mylib' would cause + mylib.so (or on some platforms, + mylib.sl) 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. +

+ PostgreSQL procedural language libraries can + be preloaded in this way, typically by using the + syntax '$libdir/plXXX' where + XXX is pgsql, perl, + tcl, or python. +

+ Only shared libraries specifically intended to be used with PostgreSQL + can be loaded this way. Every PostgreSQL-supported library has + a “magic block” 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 LD_PRELOAD for that. +

+ In general, refer to the documentation of a specific module for the + recommended way to load that module. +

local_preload_libraries (string) + + +

+ 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 LOAD 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. +

+ This option can be set by any user. Because of that, the libraries + that can be loaded are restricted to those appearing in the + plugins subdirectory of the installation's + standard library directory. (It is the database administrator's + responsibility to ensure that only “safe” libraries + are installed there.) Entries in local_preload_libraries + can specify this directory explicitly, for example + $libdir/plugins/mylib, or just specify + the library name — mylib would have + the same effect as $libdir/plugins/mylib. +

+ The intent of this feature is to allow unprivileged users to load + debugging or performance-measurement libraries into specific sessions + without requiring an explicit LOAD command. To that end, + it would be typical to set this parameter using + the PGOPTIONS environment variable on the client or by + using + ALTER ROLE SET. +

+ 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 session_preload_libraries instead. +

session_preload_libraries (string) + +

+ The intent of this feature is to allow debugging or + performance-measurement libraries to be loaded into specific sessions + without an explicit + LOAD command being given. For + example, auto_explain could be enabled for all + sessions under a given user name by setting this parameter + with ALTER ROLE SET. 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. +

+ Unlike shared_preload_libraries, 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. +

shared_preload_libraries (string) + +

+ 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 LOAD 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. +

+ 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. +

+ 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 session_preload_libraries for that + instead. +

Note

+ 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, shared_preload_libraries + is still useful on Windows hosts for libraries that need to + perform operations at postmaster start time. +

jit_provider (string) + +

+ This variable is the name of the JIT provider library to be used + (see Section 32.4.2). + The default is llvmjit. + This parameter can only be set at server start. +

+ If set to a non-existent library, JIT will not be + available, but no error will be raised. This allows JIT support to be + installed separately from the main + PostgreSQL package. +

20.11.4. Other Defaults

dynamic_library_path (string) + + +

+ If a dynamically loadable module needs to be opened and the + file name specified in the CREATE FUNCTION or + LOAD 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. +

+ The value for dynamic_library_path 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 $libdir, the + compiled-in PostgreSQL package + library directory is substituted for $libdir; this + is where the modules provided by the standard + PostgreSQL distribution are installed. + (Use pg_config --pkglibdir to find out the name of + this directory.) For example: +

+dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
+

+ or, in a Windows environment: +

+dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
+

+ The default value for this parameter is + '$libdir'. If the value is set to an empty + string, the automatic path search is turned off. +

+ This parameter can be changed at run time by superusers and users + with the appropriate SET 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 postgresql.conf configuration + file. +

gin_fuzzy_search_limit (integer) + +

+ Soft upper limit of the size of the set returned by GIN index scans. For more + information see Section 70.5. +

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