CONFIGURATION / VERSION COMPARISON
What changed?
Configuration · PostgreSQL 15 → 16
14 added · 5 removed · 27 changed · 0 coverage changes. These are changes in the pinned reference snapshots.
changedapplication_name
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -The application_name can be any string of less than NAMEDATALEN characters (64 characters in a standard build). It is typically set by an application upon connection to the server. The name will be displayed in the pg_stat_activity view and included in CSV log entries. It can also be included in regular log entries via the log_line_prefix parameter. Only printable ASCII characters may be used in the application_name value. Other characters will be replaced with question marks (?). +The application_name can be any string of less than NAMEDATALEN characters (64 characters in a standard build). It is typically set by an application upon connection to the server. The name will be displayed in the pg_stat_activity view and included in CSV log entries. It can also be included in regular log entries via the log_line_prefix parameter. Only printable ASCII characters may be used in the application_name value. Other characters are replaced with C-style hexadecimal escapes.
changedarchive_command
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -The local shell command to execute to archive a completed WAL file segment. Any %p in the string is replaced by the path name of the file to archive, and any %f is replaced by only the file name. (The path name is relative to the working directory of the server, i.e., the cluster's data directory.) Use %% to embed an actual % character in the command. It is important for the command to return a zero exit status only if it succeeds. For more information see Section 26.3.1. This parameter can only be set in the postgresql.conf file or on the server command line. It is ignored unless archive_mode was enabled at server start and archive_library is set to an empty string. If archive_command is an empty string (the default) while archive_mode is enabled (and archive_library is set to an empty string), WAL archiving is temporarily disabled, but the server continues to accumulate WAL segment files in the expectation that a command will soon be provided. Setting archive_command to a command that does nothing but return true, e.g., /bin/true (REM on Windows), effectively disables archiving, but also breaks the chain of WAL files needed for archive recovery, so it should only be used in unusual circumstances. +The local shell command to execute to archive a completed WAL file segment. Any %p in the string is replaced by the path name of the file to archive, and any %f is replaced by only the file name. (The path name is relative to the working directory of the server, i.e., the cluster's data directory.) Use %% to embed an actual % character in the command. It is important for the command to return a zero exit status only if it succeeds. For more information see Section 26.3.1. This parameter can only be set in the postgresql.conf file or on the server command line. It is only used if archive_mode was enabled at server start and archive_library is set to an empty string. If both archive_command and archive_library are set, an error will be raised. If archive_command is an empty string (the default) while archive_mode is enabled (and archive_library is set to an empty string), WAL archiving is temporarily disabled, but the server continues to accumulate WAL segment files in the expectation that a command will soon be provided. Setting archive_command to a command that does nothing but return true, e.g., /bin/true (REM on Windows), effectively disables archiving, but also breaks the chain of WAL files needed for archive recovery, so it should only be used in unusual circumstances.
changedarchive_library
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -The library to use for archiving completed WAL file segments. If set to an empty string (the default), archiving via shell is enabled, and archive_command is used. Otherwise, the specified shared library is used for archiving. The WAL archiver process is restarted by the postmaster when this parameter changes. For more information, see Section 26.3.1 and Chapter 51. This parameter can only be set in the postgresql.conf file or on the server command line. +The library to use for archiving completed WAL file segments. If set to an empty string (the default), archiving via shell is enabled, and archive_command is used. If both archive_command and archive_library are set, an error will be raised. Otherwise, the specified shared library is used for archiving. The WAL archiver process is restarted by the postmaster when this parameter changes. For more information, see Section 26.3.1 and Chapter 51. This parameter can only be set in the postgresql.conf file or on the server command line.
changedcluster_name
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -Sets a name that identifies this database cluster (instance) for various purposes. The cluster name appears in the process title for all server processes in this cluster. Moreover, it is the default application name for a standby connection (see synchronous_standby_names). The name can be any string of less than NAMEDATALEN characters (64 characters in a standard build). Only printable ASCII characters may be used in the cluster_name value. Other characters will be replaced with question marks (?). No name is shown if this parameter is set to the empty string '' (which is the default). This parameter can only be set at server start. +Sets a name that identifies this database cluster (instance) for various purposes. The cluster name appears in the process title for all server processes in this cluster. Moreover, it is the default application name for a standby connection (see synchronous_standby_names). The name can be any string of less than NAMEDATALEN characters (64 characters in a standard build). Only printable ASCII characters may be used in the cluster_name value. Other characters are replaced with C-style hexadecimal escapes. No name is shown if this parameter is set to the empty string '' (which is the default). This parameter can only be set at server start.
addedcreaterole_self_grant
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: string +context: user +boot_val: +unit: None +enumvals: None + +If a user who has CREATEROLE but not SUPERUSER creates a role, and if this is set to a non-empty value, the newly-created role will be granted to the creating user with the options specified. The value must be set, inherit, or a comma-separated list of these. The default value is an empty string, which disables the feature. The purpose of this option is to allow a CREATEROLE user who is not a superuser to automatically inherit, or automatically gain the ability to SET ROLE to, any created users. Since a CREATEROLE user is always implicitly granted ADMIN OPTION on created roles, that user could always execute a GRANT statement that would achieve the same effect as this setting. However, it can be convenient for usability reasons if the grant happens automatically. A superuser automatically inherits the privileges of every role and can always SET ROLE to any role, and this setting can be used to produce a similar behavior for CREATEROLE users for users which they create.
addeddebug_io_direct
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: string +context: postmaster +boot_val: +unit: None +enumvals: None + +Ask the kernel to minimize caching effects for relation data and WAL files using O_DIRECT (most Unix-like systems), F_NOCACHE (macOS) or FILE_FLAG_NO_BUFFERING (Windows). May be set to an empty string (the default) to disable use of direct I/O, or a comma-separated list of operations that should use direct I/O. The valid options are data for main data files, wal for WAL files, and wal_init for WAL files when being initially allocated. This parameter can only be set at server start. Some operating systems and file systems do not support direct I/O, so non-default settings may be rejected at startup or cause errors. Currently this feature reduces performance, and is intended for developer testing only.
addeddebug_logical_replication_streaming
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: enum +context: user +boot_val: buffered +unit: None +enumvals: ['buffered', 'immediate'] + +The allowed values are buffered and immediate. The default is buffered. This parameter is intended to be used to test logical decoding and replication of large transactions. The effect of debug_logical_replication_streaming is different for the publisher and subscriber: On the publisher side, debug_logical_replication_streaming allows streaming or serializing changes immediately in logical decoding. When set to immediate, stream each change if the streaming option of CREATE SUBSCRIPTION is enabled, otherwise, serialize each change. When set to buffered, the decoding will stream or serialize changes when logical_decoding_work_mem is reached. On the subscriber side, if the streaming option is set to parallel, debug_logical_replication_streaming can be used to direct the leader apply worker to send changes to the shared memory queue or to serialize all changes to the file. When set to buffered, the leader sends changes to parallel apply workers via a shared memory queue. When set to immediate, the leader serializes all changes to files and notifies the parallel apply workers to read and apply them at the end of the transaction.
addeddebug_parallel_query
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: enum +context: user +boot_val: off +unit: None +enumvals: ['off', 'on', 'regress'] + +Allows the use of parallel queries for testing purposes even in cases where no performance benefit is expected. The allowed values of debug_parallel_query are off (use parallel mode only when it is expected to improve performance), on (force parallel query for all queries for which it is thought to be safe), and regress (like on, but with additional behavior changes as explained below). More specifically, setting this value to on will add a Gather node to the top of any query plan for which this appears to be safe, so that the query runs inside of a parallel worker. Even when a parallel worker is not available or cannot be used, operations such as starting a subtransaction that would be prohibited in a parallel query context will be prohibited unless the planner believes that this will cause the query to fail. If failures or unexpected results occur when this option is set, some functions used by the query may need to be marked PARALLEL UNSAFE (or, possibly, PARALLEL RESTRICTED). Setting this value to regress has all of the same effects as setting it to on plus some additional effects that are intended to facilitate automated regression testing. Normally, messages from a parallel worker include a context line indicating that, but a setting of regress suppresses this line so that the output is the same as in non-parallel execution. Also, the Gather nodes added to plans by this setting are hidden in EXPLAIN output so that the output matches what would be obtained if this setting were turned off.
addedenable_presorted_aggregate
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: bool +context: user +boot_val: on +unit: None +enumvals: None + +Controls if the query planner will produce a plan which will provide rows which are presorted in the order required for the query's ORDER BY / DISTINCT aggregate functions. When disabled, the query planner will produce a plan which will always require the executor to perform a sort before performing aggregation of each aggregate function containing an ORDER BY or DISTINCT clause. When enabled, the planner will try to produce a more efficient plan which provides input to the aggregate functions which is presorted in the order they require for aggregation. The default value is on.
addedfile_extend_method
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: enum +context: sighup +boot_val: posix_fallocate +unit: None +enumvals: ['posix_fallocate', 'write_zeros'] + +Specifies the method used to extend data files during bulk operations such as COPY. The first available option is used as the default, depending on the operating system: posix_fallocate (Unix) uses the standard POSIX interface for allocating disk space, but is missing on some systems. If it is present but the underlying file system doesn't support it, this option silently falls back to write_zeros. Current versions of BTRFS are known to disable compression when this option is used. This is the default on systems that have the function. write_zeros extends files by writing out blocks of zero bytes. This is the default on systems that don't have the function posix_fallocate. The write_zeros method is always used when data files are extended by 8 blocks or fewer.
removedforce_parallel_mode
--- 15 +++ 16 @@ -1,7 +0,0 @@ -vartype: enum -context: user -boot_val: off -unit: None -enumvals: ['off', 'on', 'regress'] - -Allows the use of parallel queries for testing purposes even in cases where no performance benefit is expected. The allowed values of force_parallel_mode are off (use parallel mode only when it is expected to improve performance), on (force parallel query for all queries for which it is thought to be safe), and regress (like on, but with additional behavior changes as explained below). More specifically, setting this value to on will add a Gather node to the top of any query plan for which this appears to be safe, so that the query runs inside of a parallel worker. Even when a parallel worker is not available or cannot be used, operations such as starting a subtransaction that would be prohibited in a parallel query context will be prohibited unless the planner believes that this will cause the query to fail. If failures or unexpected results occur when this option is set, some functions used by the query may need to be marked PARALLEL UNSAFE (or, possibly, PARALLEL RESTRICTED). Setting this value to regress has all of the same effects as setting it to on plus some additional effects that are intended to facilitate automated regression testing. Normally, messages from a parallel worker include a context line indicating that, but a setting of regress suppresses this line so that the output is the same as in non-parallel execution. Also, the Gather nodes added to plans by this setting are hidden in EXPLAIN output so that the output matches what would be obtained if this setting were turned off.
addedgss_accept_delegation
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: bool +context: sighup +boot_val: off +unit: None +enumvals: None + +Sets whether GSSAPI delegation should be accepted from the client. The default is off meaning credentials from the client will not be accepted. Changing this to on will make the server accept credentials delegated to it from the client. This parameter can only be set in the postgresql.conf file or on the server command line.
addedicu_validation_level
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: enum +context: user +boot_val: warning +unit: None +enumvals: ['disabled', 'debug5', 'debug4', 'debug3', 'debug2', 'debug1', 'log', 'notice', 'warning', 'error'] + +When ICU locale validation problems are encountered, controls which message level is used to report the problem. Valid values are DISABLED, DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1, INFO, NOTICE, WARNING, ERROR, and LOG. If set to DISABLED, does not report validation problems at all. Otherwise reports problems at the given message level. The default is WARNING.
removedlc_collate
--- 15 +++ 16 @@ -1,7 +0,0 @@ -vartype: string -context: internal -boot_val: C -unit: None -enumvals: None - -Reports the locale in which sorting of textual data is done. See Section 24.1 for more information. This value is determined when a database is created.
removedlc_ctype
--- 15 +++ 16 @@ -1,7 +0,0 @@ -vartype: string -context: internal -boot_val: C -unit: None -enumvals: None - -Reports the locale that determines character classifications. See Section 24.1 for more information. This value is determined when a database is created. Ordinarily this will be the same as lc_collate, but for special applications it might be set differently.
changedlog_line_prefix
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -This is a printf-style string that is output at the beginning of each log line. % characters begin “escape sequences” that are replaced with status information as outlined below. Unrecognized escapes are ignored. Other characters are copied straight to the log line. Some escapes are only recognized by session processes, and will be treated as empty by background processes such as the main server process. Status information may be aligned either left or right by specifying a numeric literal after the % and before the option. A negative value will cause the status information to be padded on the right with spaces to give it a minimum width, whereas a positive value will pad on the left. Padding can be useful to aid human readability in log files. This parameter can only be set in the postgresql.conf file or on the server command line. The default is '%m [%p] ' which logs a time stamp and the process ID. Escape Effect Session only %a Application name yes %u User name yes %d Database name yes %r Remote host name or IP address, and remote port yes %h Remote host name or IP address yes %b Backend type no %p Process ID no %P Process ID of the parallel group leader, if this process is a parallel query worker no %t Time stamp without milliseconds no %m Time stamp with milliseconds no %n Time stamp with milliseconds (as a Unix epoch) no %i Command tag: type of session's current command yes %e SQLSTATE error code no %c Session ID: see below no %l Number of the log line for each session or process, starting at 1 no %s Process start time stamp no %v Virtual transaction ID (backendID/localXID) no %x Transaction ID (0 if none is assigned) no %q Produces no output, but tells non-session processes to stop at this point in the string; ignored by session processes no %Q Query identifier of the current query. Query identifiers are not computed by default, so this field will be zero unless compute_query_id parameter is enabled or a third-party module that computes query identifiers is configured. yes %% Literal % no The backend type corresponds to the column backend_type in the view pg_stat_activity, but additional types can appear in the log that don't show in that view. The %c escape prints a quasi-unique session identifier, consisting of two 4-byte hexadecimal numbers (without leading zeros) separated by a dot. The numbers are the process start time and the process ID, so %c can also be used as a space saving way of printing those items. For example, to generate the session identifier from pg_stat_activity, use this query: SELECT to_hex(trunc(EXTRACT(EPOCH FROM backend_start))::integer) || '.' || to_hex(pid) FROM pg_stat_activity; Tip If you set a nonempty value for log_line_prefix, you should usually make its last character be a space, to provide visual separation from the rest of the log line. A punctuation character can be used too. Tip Syslog produces its own time stamp and process ID information, so you probably do not want to include those escapes if you are logging to syslog. Tip The %q escape is useful when including information that is only available in session (backend) context like user or database name. For example: log_line_prefix = '%m [%p] %q%u@%d/%a ' Note The %Q escape always reports a zero identifier for lines output by log_statement because log_statement generates output before an identifier can be calculated, including invalid statements for which an identifier cannot be calculated. +This is a printf-style string that is output at the beginning of each log line. % characters begin “escape sequences” that are replaced with status information as outlined below. Unrecognized escapes are ignored. Other characters are copied straight to the log line. Some escapes are only recognized by session processes, and will be treated as empty by background processes such as the main server process. Status information may be aligned either left or right by specifying a numeric literal after the % and before the option. A negative value will cause the status information to be padded on the right with spaces to give it a minimum width, whereas a positive value will pad on the left. Padding can be useful to aid human readability in log files. This parameter can only be set in the postgresql.conf file or on the server command line. The default is '%m [%p] ' which logs a time stamp and the process ID. Escape Effect Session only %a Application name yes %u User name yes %d Database name yes %r Remote host name or IP address, and remote port yes %h Remote host name or IP address yes %b Backend type no %p Process ID no %P Process ID of the parallel group leader, if this process is a parallel query worker no %t Time stamp without milliseconds no %m Time stamp with milliseconds no %n Time stamp with milliseconds (as a Unix epoch) no %i Command tag: type of session's current command yes %e SQLSTATE error code no %c Session ID: see below no %l Number of the log line for each session or process, starting at 1 no %s Process start time stamp no %v Virtual transaction ID (backendID/localXID); see Section 74.1 no %x Transaction ID (0 if none is assigned); see Section 74.1 no %q Produces no output, but tells non-session processes to stop at this point in the string; ignored by session processes no %Q Query identifier of the current query. Query identifiers are not computed by default, so this field will be zero unless compute_query_id parameter is enabled or a third-party module that computes query identifiers is configured. yes %% Literal % no The backend type corresponds to the column backend_type in the view pg_stat_activity, but additional types can appear in the log that don't show in that view. The %c escape prints a quasi-unique session identifier, consisting of two 4-byte hexadecimal numbers (without leading zeros) separated by a dot. The numbers are the process start time and the process ID, so %c can also be used as a space saving way of printing those items. For example, to generate the session identifier from pg_stat_activity, use this query: SELECT to_hex(trunc(EXTRACT(EPOCH FROM backend_start))::integer) || '.' || to_hex(pid) FROM pg_stat_activity; Tip If you set a nonempty value for log_line_prefix, you should usually make its last character be a space, to provide visual separation from the rest of the log line. A punctuation character can be used too. Tip Syslog produces its own time stamp and process ID information, so you probably do not want to include those escapes if you are logging to syslog. Tip The %q escape is useful when including information that is only available in session (backend) context like user or database name. For example: log_line_prefix = '%m [%p] %q%u@%d/%a ' Note The %Q escape always reports a zero identifier for lines output by log_statement because log_statement generates output before an identifier can be calculated, including invalid statements for which an identifier cannot be calculated.
changedlog_temp_files
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: kB enumvals: None -Controls logging of temporary file names and sizes. Temporary files can be created for sorts, hashes, and temporary query results. If enabled by this setting, a log entry is emitted for each temporary file when it is deleted. A value of zero logs all temporary file information, while positive values log only files whose size is greater than or equal to the specified amount of data. If this value is specified without units, it is taken as kilobytes. The default setting is -1, which disables such logging. Only superusers and users with the appropriate SET privilege can change this setting. +Controls logging of temporary file names and sizes. Temporary files can be created for sorts, hashes, and temporary query results. If enabled by this setting, a log entry is emitted for each temporary file, with the file size specified in bytes, when it is deleted. A value of zero logs all temporary file information, while positive values log only files whose size is greater than or equal to the specified amount of data. If this value is specified without units, it is taken as kilobytes. The default setting is -1, which disables such logging. Only superusers and users with the appropriate SET privilege can change this setting.
changedmax_locks_per_transaction
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -The shared lock table tracks locks on max_locks_per_transaction * (max_connections + max_prepared_transactions) objects (e.g., tables); hence, no more than this many distinct objects can be locked at any one time. This parameter controls the average number of object locks allocated for each transaction; individual transactions can lock more objects as long as the locks of all transactions fit in the lock table. This is not the number of rows that can be locked; that value is unlimited. The default, 64, has historically proven sufficient, but you might need to raise this value if you have queries that touch many different tables in a single transaction, e.g., query of a parent table with many children. This parameter can only be set at server start. When running a standby server, you must set this parameter to the same or higher value than on the primary server. Otherwise, queries will not be allowed in the standby server. +The shared lock table has space for max_locks_per_transaction objects (e.g., tables) per server process or prepared transaction; hence, no more than this many distinct objects can be locked at any one time. This parameter limits the average number of object locks used by each transaction; individual transactions can lock more objects as long as the locks of all transactions fit in the lock table. This is not the number of rows that can be locked; that value is unlimited. The default, 64, has historically proven sufficient, but you might need to raise this value if you have queries that touch many different tables in a single transaction, e.g., query of a parent table with many children. This parameter can only be set at server start. When running a standby server, you must set this parameter to have the same or higher value as on the primary server. Otherwise, queries will not be allowed in the standby server.
changedmax_logical_replication_workers
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -Specifies maximum number of logical replication workers. This includes both apply workers and table synchronization workers. Logical replication workers are taken from the pool defined by max_worker_processes. The default value is 4. This parameter can only be set at server start. +Specifies maximum number of logical replication workers. This includes leader apply workers, parallel apply workers, and table synchronization workers. Logical replication workers are taken from the pool defined by max_worker_processes. The default value is 4. This parameter can only be set at server start.
addedmax_parallel_apply_workers_per_subscription
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: integer +context: sighup +boot_val: 2 +unit: None +enumvals: None + +Maximum number of parallel apply workers per subscription. This parameter controls the amount of parallelism for streaming of in-progress transactions with subscription parameter streaming = parallel. The parallel apply workers are taken from the pool defined by max_logical_replication_workers. The default value is 2. This parameter can only be set in the postgresql.conf file or on the server command line.
changedmax_pred_locks_per_transaction
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -The shared predicate lock table tracks locks on max_pred_locks_per_transaction * (max_connections + max_prepared_transactions) objects (e.g., tables); hence, no more than this many distinct objects can be locked at any one time. This parameter controls the average number of object locks allocated for each transaction; individual transactions can lock more objects as long as the locks of all transactions fit in the lock table. This is not the number of rows that can be locked; that value is unlimited. The default, 64, has generally been sufficient in testing, but you might need to raise this value if you have clients that touch many different tables in a single serializable transaction. This parameter can only be set at server start. +The shared predicate lock table has space for max_pred_locks_per_transaction objects (e.g., tables) per server process or prepared transaction; hence, no more than this many distinct objects can be locked at any one time. This parameter limits the average number of object locks used by each transaction; individual transactions can lock more objects as long as the locks of all transactions fit in the lock table. This is not the number of rows that can be locked; that value is unlimited. The default, 64, has historically proven sufficient, but you might need to raise this value if you have clients that touch many different tables in a single serializable transaction. This parameter can only be set at server start.
changedmax_replication_slots
--- 15 +++ 16 @@ -4,4 +4,6 @@ unit: None enumvals: None -Specifies the maximum number of replication slots (see Section 27.2.6) that the server can support. The default is 10. This parameter can only be set at server start. Setting it to a lower value than the number of currently existing replication slots will prevent the server from starting. Also, wal_level must be set to replica or higher to allow replication slots to be used. On the subscriber side, specifies how many replication origins (see Chapter 50) can be tracked simultaneously, effectively limiting how many logical replication subscriptions can be created on the server. Setting it to a lower value than the current number of tracked replication origins (reflected in pg_replication_origin_status, not pg_replication_origin) will prevent the server from starting. +Specifies the maximum number of replication slots (see Section 27.2.6) that the server can support. The default is 10. This parameter can only be set at server start. Setting it to a lower value than the number of currently existing replication slots will prevent the server from starting. Also, wal_level must be set to replica or higher to allow replication slots to be used. Note that this parameter also applies on the subscriber side, but with a different meaning. + +Specifies how many replication origins (see Chapter 50) can be tracked simultaneously, effectively limiting how many logical replication subscriptions can be created on the server. Setting it to a lower value than the current number of tracked replication origins (reflected in pg_replication_origin_status) will prevent the server from starting. max_replication_slots must be set to at least the number of subscriptions that will be added to the subscriber, plus some reserve for table synchronization. Note that this parameter also applies on a sending server, but with a different meaning.
removedpromote_trigger_file
--- 15 +++ 16 @@ -1,7 +0,0 @@ -vartype: string -context: sighup -boot_val: -unit: None -enumvals: None - -Specifies a trigger file whose presence ends recovery in the standby. Even if this value is not set, you can still promote the standby using pg_ctl promote or calling pg_promote(). This parameter can only be set in the postgresql.conf file or on the server command line.
changedrecovery_target_action
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: ['pause', 'promote', 'shutdown'] -Specifies what action the server should take once the recovery target is reached. The default is pause, which means recovery will be paused. promote means the recovery process will finish and the server will start to accept connections. Finally shutdown will stop the server after reaching the recovery target. The intended use of the pause setting is to allow queries to be executed against the database to check if this recovery target is the most desirable point for recovery. The paused state can be resumed by using pg_wal_replay_resume() (see Table 9.91), which then causes recovery to end. If this recovery target is not the desired stopping point, then shut down the server, change the recovery target settings to a later target and restart to continue recovery. The shutdown setting is useful to have the instance ready at the exact replay point desired. The instance will still be able to replay more WAL records (and in fact will have to replay WAL records since the last checkpoint next time it is started). Note that because recovery.signal will not be removed when recovery_target_action is set to shutdown, any subsequent start will end with immediate shutdown unless the configuration is changed or the recovery.signal file is removed manually. This setting has no effect if no recovery target is set. If hot_standby is not enabled, a setting of pause will act the same as shutdown. If the recovery target is reached while a promotion is ongoing, a setting of pause will act the same as promote. In any case, if a recovery target is configured but the archive recovery ends before the target is reached, the server will shut down with a fatal error. +Specifies what action the server should take once the recovery target is reached. The default is pause, which means recovery will be paused. promote means the recovery process will finish and the server will start to accept connections. Finally shutdown will stop the server after reaching the recovery target. The intended use of the pause setting is to allow queries to be executed against the database to check if this recovery target is the most desirable point for recovery. The paused state can be resumed by using pg_wal_replay_resume() (see Table 9.93), which then causes recovery to end. If this recovery target is not the desired stopping point, then shut down the server, change the recovery target settings to a later target and restart to continue recovery. The shutdown setting is useful to have the instance ready at the exact replay point desired. The instance will still be able to replay more WAL records (and in fact will have to replay WAL records since the last checkpoint next time it is started). Note that because recovery.signal will not be removed when recovery_target_action is set to shutdown, any subsequent start will end with immediate shutdown unless the configuration is changed or the recovery.signal file is removed manually. This setting has no effect if no recovery target is set. If hot_standby is not enabled, a setting of pause will act the same as shutdown. If the recovery target is reached while a promotion is ongoing, a setting of pause will act the same as promote. In any case, if a recovery target is configured but the archive recovery ends before the target is reached, the server will shut down with a fatal error.
changedrecovery_target_timeline
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -Specifies recovering into a particular timeline. The value can be a numeric timeline ID or a special value. The value current recovers along the same timeline that was current when the base backup was taken. The value latest recovers to the latest timeline found in the archive, which is useful in a standby server. latest is the default. You usually only need to set this parameter in complex re-recovery situations, where you need to return to a state that itself was reached after a point-in-time recovery. See Section 26.3.5 for discussion. +Specifies recovering into a particular timeline. The value can be a numeric timeline ID or a special value. The value current recovers along the same timeline that was current when the base backup was taken. The value latest recovers to the latest timeline found in the archive, which is useful in a standby server. latest is the default. To specify a timeline ID in hexadecimal (for example, if extracted from a WAL file name or history file), prefix it with a 0x. For instance, if the WAL file name is 00000011000000A10000004F, then the timeline ID is 0x11 (or 17 decimal). You usually only need to set this parameter in complex re-recovery situations, where you need to return to a state that itself was reached after a point-in-time recovery. See Section 26.3.5 for discussion.
addedreserved_connections
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: integer +context: postmaster +boot_val: 0 +unit: None +enumvals: None + +Determines the number of connection “slots” that are reserved for connections by roles with privileges of the pg_use_reserved_connections role. Whenever the number of free connection slots is greater than superuser_reserved_connections but less than or equal to the sum of superuser_reserved_connections and reserved_connections, new connections will be accepted only for superusers and roles with privileges of pg_use_reserved_connections. If superuser_reserved_connections or fewer connection slots are available, new connections will be accepted only for superusers. The default value is zero connections. The value must be less than max_connections minus superuser_reserved_connections. This parameter can only be set at server start.
addedscram_iterations
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: integer +context: user +boot_val: 4096 +unit: None +enumvals: None + +The number of computational iterations to be performed when encrypting a password using SCRAM-SHA-256. The default is 4096. A higher number of iterations provides additional protection against brute-force attacks on stored passwords, but makes authentication slower. Changing the value has no effect on existing passwords encrypted with SCRAM-SHA-256 as the iteration count is fixed at the time of encryption. In order to make use of a changed value, a new password must be set. Note If a role password was created with a different iteration count than the value of scram_iterations specified in the postgresql.conf file or on the server command line, an unauthenticated user can discern the existence of the role by observing discrepancies in the server's responses to connection attempts. If you find this concerning, ensure that all role passwords are created with scram_iterations set to the value specified in the postgresql.conf file or on the server command line.
addedsend_abort_for_crash
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: bool +context: sighup +boot_val: off +unit: None +enumvals: None + +By default, after a backend crash the postmaster will stop remaining child processes by sending them SIGQUIT signals, which permits them to exit more-or-less gracefully. When this option is set to on, SIGABRT is sent instead. That normally results in production of a core dump file for each such child process. This can be handy for investigating the states of other processes after a crash. It can also consume lots of disk space in the event of repeated crashes, so do not enable this on systems you are not monitoring carefully. Beware that no support exists for cleaning up the core file(s) automatically. This parameter can only be set in the postgresql.conf file or on the server command line.
addedsend_abort_for_kill
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: bool +context: sighup +boot_val: off +unit: None +enumvals: None + +By default, after attempting to stop a child process with SIGQUIT, the postmaster will wait five seconds and then send SIGKILL to force immediate termination. When this option is set to on, SIGABRT is sent instead of SIGKILL. That normally results in production of a core dump file for each such child process. This can be handy for investigating the states of “stuck” child processes. It can also consume lots of disk space in the event of repeated crashes, so do not enable this on systems you are not monitoring carefully. Beware that no support exists for cleaning up the core file(s) automatically. This parameter can only be set in the postgresql.conf file or on the server command line.
changedserver_version
--- 15 +++ 16 @@ -1,6 +1,6 @@ vartype: string context: internal -boot_val: 15.19 (Debian 15.19-1.pgdg13+2) +boot_val: 16.15 (Debian 16.15-1.pgdg13+2) unit: None enumvals: None
changedserver_version_num
--- 15 +++ 16 @@ -1,6 +1,6 @@ vartype: integer context: internal -boot_val: 150019 +boot_val: 160015 unit: None enumvals: None
changedssl_ciphers
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -Specifies a list of SSL cipher suites that are allowed to be used by SSL connections. See the ciphers manual page in the OpenSSL package for the syntax of this setting and a list of supported values. Only connections using TLS version 1.2 and lower are affected. There is currently no setting that controls the cipher choices used by TLS version 1.3 connections. The default value is HIGH:MEDIUM:+3DES:!aNULL. The default is usually a reasonable choice unless you have specific security requirements. This parameter can only be set in the postgresql.conf file or on the server command line. Explanation of the default value: HIGH Cipher suites that use ciphers from HIGH group (e.g., AES, Camellia, 3DES) MEDIUM Cipher suites that use ciphers from MEDIUM group (e.g., RC4, SEED) +3DES The OpenSSL default order for HIGH is problematic because it orders 3DES higher than AES128. This is wrong because 3DES offers less security than AES128, and it is also much slower. +3DES reorders it after all other HIGH and MEDIUM ciphers. !aNULL Disables anonymous cipher suites that do no authentication. Such cipher suites are vulnerable to MITM attacks and therefore should not be used. Available cipher suite details will vary across OpenSSL versions. Use the command openssl ciphers -v 'HIGH:MEDIUM:+3DES:!aNULL' to see actual details for the currently installed OpenSSL version. Note that this list is filtered at run time based on the server key type. +Specifies a list of SSL cipher suites that are allowed to be used by SSL connections. See the ciphers manual page in the OpenSSL package for the syntax of this setting and a list of supported values. Only connections using TLS version 1.2 and lower are affected. There is currently no setting that controls the cipher choices used by TLS version 1.3 connections. The default value is HIGH:MEDIUM:+3DES:!aNULL. The default is usually a reasonable choice unless you have specific security requirements. This parameter can only be set in the postgresql.conf file or on the server command line. Explanation of the default value: HIGH # Cipher suites that use ciphers from HIGH group (e.g., AES, Camellia, 3DES) MEDIUM # Cipher suites that use ciphers from MEDIUM group (e.g., RC4, SEED) +3DES # The OpenSSL default order for HIGH is problematic because it orders 3DES higher than AES128. This is wrong because 3DES offers less security than AES128, and it is also much slower. +3DES reorders it after all other HIGH and MEDIUM ciphers. !aNULL # Disables anonymous cipher suites that do no authentication. Such cipher suites are vulnerable to MITM attacks and therefore should not be used. Available cipher suite details will vary across OpenSSL versions. Use the command openssl ciphers -v 'HIGH:MEDIUM:+3DES:!aNULL' to see actual details for the currently installed OpenSSL version. Note that this list is filtered at run time based on the server key type.
changedsuperuser_reserved_connections
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -Determines the number of connection “slots” that are reserved for connections by PostgreSQL superusers. At most max_connections connections can ever be active simultaneously. Whenever the number of active concurrent connections is at least max_connections minus superuser_reserved_connections, new connections will be accepted only for superusers, and no new replication connections will be accepted. The default value is three connections. The value must be less than max_connections. This parameter can only be set at server start. +Determines the number of connection “slots” that are reserved for connections by PostgreSQL superusers. At most max_connections connections can ever be active simultaneously. Whenever the number of active concurrent connections is at least max_connections minus superuser_reserved_connections, new connections will be accepted only for superusers. The connection slots reserved by this parameter are intended as final reserve for emergency use after the slots reserved by reserved_connections have been exhausted. The default value is three connections. The value must be less than max_connections minus reserved_connections. This parameter can only be set at server start.
changedtcp_keepalives_count
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -Specifies the number of TCP keepalive messages that can be lost before the server's connection to the client is considered dead. A value of 0 (the default) selects the operating system's default. This parameter is supported only on systems that support TCP_KEEPCNT or an equivalent socket option; on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero. Note This parameter is not supported on Windows, and must be zero. +Specifies the number of TCP keepalive messages that can be lost before the server's connection to the client is considered dead. A value of 0 (the default) selects the operating system's default. This parameter is supported only on systems that support TCP_KEEPCNT or an equivalent socket option (which does not include Windows); on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero.
changedtcp_keepalives_idle
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: s enumvals: None -Specifies the amount of time with no network activity after which the operating system should send a TCP keepalive message to the client. If this value is specified without units, it is taken as seconds. A value of 0 (the default) selects the operating system's default. This parameter is supported only on systems that support TCP_KEEPIDLE or an equivalent socket option, and on Windows; on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero. Note On Windows, setting a value of 0 will set this parameter to 2 hours, since Windows does not provide a way to read the system default value. +Specifies the amount of time with no network activity after which the operating system should send a TCP keepalive message to the client. If this value is specified without units, it is taken as seconds. A value of 0 (the default) selects the operating system's default. On Windows, setting a value of 0 will set this parameter to 2 hours, since Windows does not provide a way to read the system default value. This parameter is supported only on systems that support TCP_KEEPIDLE or an equivalent socket option, and on Windows; on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero.
changedtcp_keepalives_interval
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: s enumvals: None -Specifies the amount of time after which a TCP keepalive message that has not been acknowledged by the client should be retransmitted. If this value is specified without units, it is taken as seconds. A value of 0 (the default) selects the operating system's default. This parameter is supported only on systems that support TCP_KEEPINTVL or an equivalent socket option, and on Windows; on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero. Note On Windows, setting a value of 0 will set this parameter to 1 second, since Windows does not provide a way to read the system default value. +Specifies the amount of time after which a TCP keepalive message that has not been acknowledged by the client should be retransmitted. If this value is specified without units, it is taken as seconds. A value of 0 (the default) selects the operating system's default. On Windows, setting a value of 0 will set this parameter to 1 second, since Windows does not provide a way to read the system default value. This parameter is supported only on systems that support TCP_KEEPINTVL or an equivalent socket option, and on Windows; on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero.
changedtcp_user_timeout
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: ms enumvals: None -Specifies the amount of time that transmitted data may remain unacknowledged before the TCP connection is forcibly closed. If this value is specified without units, it is taken as milliseconds. A value of 0 (the default) selects the operating system's default. This parameter is supported only on systems that support TCP_USER_TIMEOUT; on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero. Note This parameter is not supported on Windows, and must be zero. +Specifies the amount of time that transmitted data may remain unacknowledged before the TCP connection is forcibly closed. If this value is specified without units, it is taken as milliseconds. A value of 0 (the default) selects the operating system's default. This parameter is supported only on systems that support TCP_USER_TIMEOUT (which does not include Windows); on other systems, it must be zero. In sessions connected via a Unix-domain socket, this parameter is ignored and always reads as zero.
changedtrack_io_timing
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -Enables timing of database I/O calls. This parameter is off by default, as it will repeatedly query the operating system for the current time, which may cause significant overhead on some platforms. You can use the pg_test_timing tool to measure the overhead of timing on your system. I/O timing information is displayed in pg_stat_database, in the output of EXPLAIN when the BUFFERS option is used, in the output of VACUUM when the VERBOSE option is used, by autovacuum for auto-vacuums and auto-analyzes, when log_autovacuum_min_duration is set and by pg_stat_statements. Only superusers and users with the appropriate SET privilege can change this setting. +Enables timing of database I/O calls. This parameter is off by default, as it will repeatedly query the operating system for the current time, which may cause significant overhead on some platforms. You can use the pg_test_timing tool to measure the overhead of timing on your system. I/O timing information is displayed in pg_stat_database, pg_stat_io, in the output of EXPLAIN when the BUFFERS option is used, in the output of VACUUM when the VERBOSE option is used, by autovacuum for auto-vacuums and auto-analyzes, when log_autovacuum_min_duration is set and by pg_stat_statements. Only superusers and users with the appropriate SET privilege can change this setting.
addedvacuum_buffer_usage_limit
--- 15 +++ 16 @@ -0,0 +1,7 @@ +vartype: integer +context: user +boot_val: 256 +unit: kB +enumvals: None + +Specifies the size of the Buffer Access Strategy used by the VACUUM and ANALYZE commands. A setting of 0 will allow the operation to use any number of shared_buffers. Otherwise valid sizes range from 128 kB to 16 GB. If the specified size would exceed 1/8 the size of shared_buffers, the size is silently capped to that value. The default value is 256 kB. If this value is specified without units, it is taken as kilobytes. This parameter can be set at any time. It can be overridden for VACUUM and ANALYZE when passing the BUFFER_USAGE_LIMIT option. Higher settings can allow VACUUM and ANALYZE to run more quickly, but having too large a setting may cause too many other useful pages to be evicted from shared buffers.
removedvacuum_defer_cleanup_age
--- 15 +++ 16 @@ -1,7 +0,0 @@ -vartype: integer -context: sighup -boot_val: 0 -unit: None -enumvals: None - -Specifies the number of transactions by which VACUUM and HOT updates will defer cleanup of dead row versions. The default is zero transactions, meaning that dead row versions can be removed as soon as possible, that is, as soon as they are no longer visible to any open transaction. You may wish to set this to a non-zero value on a primary server that is supporting hot standby servers, as described in Section 27.4. This allows more time for queries on the standby to complete without incurring conflicts due to early cleanup of rows. However, since the value is measured in terms of number of write transactions occurring on the primary server, it is difficult to predict just how much additional grace time will be made available to standby queries. This parameter can only be set in the postgresql.conf file or on the server command line. You should also consider setting hot_standby_feedback on standby server(s) as an alternative to using this parameter. This does not prevent cleanup of dead rows which have reached the age specified by old_snapshot_threshold.
changedvacuum_failsafe_age
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -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. +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, further non-essential maintenance tasks (such as index vacuuming) are bypassed, and any Buffer Access Strategy in use will be disabled resulting in VACUUM being free to make use of all of shared buffers. 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.
changedvacuum_freeze_min_age
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -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. +Specifies the cutoff age (in transactions) that VACUUM should use to decide whether to trigger freezing of pages that have an older XID. 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.
changedvacuum_multixact_freeze_min_age
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: None -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. +Specifies the cutoff age (in multixacts) that VACUUM should use to decide whether to trigger freezing of pages with an older multixact ID. 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.
changedwal_keep_size
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: MB enumvals: None -Specifies the minimum size of past log file segments kept in the pg_wal directory, in case a standby server needs to fetch them for streaming replication. If a standby server connected to the sending server falls behind by more than wal_keep_size megabytes, the sending server might remove a WAL segment still needed by the standby, in which case the replication connection will be terminated. Downstream connections will also eventually fail as a result. (However, the standby server can recover by fetching the segment from archive, if WAL archiving is in use.) This sets only the minimum size of segments retained in pg_wal; the system might need to retain more segments for WAL archival or to recover from a checkpoint. If wal_keep_size is zero (the default), the system doesn't keep any extra segments for standby purposes, so the number of old WAL segments available to standby servers is a function of the location of the previous checkpoint and status of WAL archiving. If this value is specified without units, it is taken as megabytes. This parameter can only be set in the postgresql.conf file or on the server command line. +Specifies the minimum size of past WAL files kept in the pg_wal directory, in case a standby server needs to fetch them for streaming replication. If a standby server connected to the sending server falls behind by more than wal_keep_size megabytes, the sending server might remove a WAL segment still needed by the standby, in which case the replication connection will be terminated. Downstream connections will also eventually fail as a result. (However, the standby server can recover by fetching the segment from archive, if WAL archiving is in use.) This sets only the minimum size of segments retained in pg_wal; the system might need to retain more segments for WAL archival or to recover from a checkpoint. If wal_keep_size is zero (the default), the system doesn't keep any extra segments for standby purposes, so the number of old WAL segments available to standby servers is a function of the location of the previous checkpoint and status of WAL archiving. If this value is specified without units, it is taken as megabytes. This parameter can only be set in the postgresql.conf file or on the server command line.
changedwal_retrieve_retry_interval
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: ms enumvals: None -Specifies how long the standby server should wait when WAL data is not available from any sources (streaming replication, local pg_wal or WAL archive) before trying again to retrieve WAL data. If this value is specified without units, it is taken as milliseconds. The default value is 5 seconds. This parameter can only be set in the postgresql.conf file or on the server command line. This parameter is useful in configurations where a node in recovery needs to control the amount of time to wait for new WAL data to be available. For example, in archive recovery, it is possible to make the recovery more responsive in the detection of a new WAL log file by reducing the value of this parameter. On a system with low WAL activity, increasing it reduces the amount of requests necessary to access WAL archives, something useful for example in cloud environments where the number of times an infrastructure is accessed is taken into account. +Specifies how long the standby server should wait when WAL data is not available from any sources (streaming replication, local pg_wal or WAL archive) before trying again to retrieve WAL data. If this value is specified without units, it is taken as milliseconds. The default value is 5 seconds. This parameter can only be set in the postgresql.conf file or on the server command line. This parameter is useful in configurations where a node in recovery needs to control the amount of time to wait for new WAL data to be available. For example, in archive recovery, it is possible to make the recovery more responsive in the detection of a new WAL file by reducing the value of this parameter. On a system with low WAL activity, increasing it reduces the amount of requests necessary to access WAL archives, something useful for example in cloud environments where the number of times an infrastructure is accessed is taken into account. In logical replication, this parameter also limits how often a failing replication apply worker will be respawned.
changedwal_sync_method
--- 15 +++ 16 @@ -4,4 +4,4 @@ unit: None enumvals: ['fsync', 'fdatasync', 'open_sync', 'open_datasync'] -Method used for forcing WAL updates out to disk. If fsync is off then this setting is irrelevant, since WAL file updates will not be forced out at all. Possible values are: open_datasync (write WAL files with open() option O_DSYNC) fdatasync (call fdatasync() at each commit) fsync (call fsync() at each commit) fsync_writethrough (call fsync() at each commit, forcing write-through of any disk write cache) open_sync (write WAL files with open() option O_SYNC) The open_* options also use O_DIRECT if available. Not all of these choices are available on all platforms. The default is the first method in the above list that is supported by the platform, except that fdatasync is the default on Linux and FreeBSD. The default is not necessarily ideal; it might be necessary to change this setting or other aspects of your system configuration in order to create a crash-safe configuration or achieve optimal performance. These aspects are discussed in Section 30.1. This parameter can only be set in the postgresql.conf file or on the server command line. +Method used for forcing WAL updates out to disk. If fsync is off then this setting is irrelevant, since WAL file updates will not be forced out at all. Possible values are: open_datasync (write WAL files with open() option O_DSYNC) fdatasync (call fdatasync() at each commit) fsync (call fsync() at each commit) fsync_writethrough (call fsync() at each commit, forcing write-through of any disk write cache) open_sync (write WAL files with open() option O_SYNC) Not all of these choices are available on all platforms. The default is the first method in the above list that is supported by the platform, except that fdatasync is the default on Linux and FreeBSD. The default is not necessarily ideal; it might be necessary to change this setting or other aspects of your system configuration in order to create a crash-safe configuration or achieve optimal performance. These aspects are discussed in Section 30.1. This parameter can only be set in the postgresql.conf file or on the server command line.