【pgsql-参数详解1】PostgreSQL默认参数值

àì夳堔傛蜴生んèń 2022-02-27 02:24 915阅读 0赞

如果pgsql的参数文件都是用默认值，各个参数值是多少了，这里贴出来给大家做个参考。  
安装pgsql后不做任何配置。

name                  |                setting                |                                                          description                                                          
    ----------------------------------------+---------------------------------------+-------------------------------------------------------------------------------------------------------------------------------
     allow_system_table_mods                | off                                   | Allows modifications of the structure of system tables.
     application_name                       | psql                                  | Sets the application name to be reported in statistics and logs.
     archive_command                        | (disabled)                            | Sets the shell command that will be called to archive a WAL file.
     archive_mode                           | off                                   | Allows archiving of WAL files using archive_command.
     archive_timeout                        | 0                                     | Forces a switch to the next WAL file if a new file has not been started within N seconds.
     array_nulls                            | on                                    | Enable input of NULL elements in arrays.
     authentication_timeout                 | 1min                                  | Sets the maximum allowed time to complete client authentication.
     autovacuum                             | on                                    | Starts the autovacuum subprocess.
     autovacuum_analyze_scale_factor        | 0.1                                   | Number of tuple inserts, updates, or deletes prior to analyze as a fraction of reltuples.
     autovacuum_analyze_threshold           | 50                                    | Minimum number of tuple inserts, updates, or deletes prior to analyze.
     autovacuum_freeze_max_age              | 200000000                             | Age at which to autovacuum a table to prevent transaction ID wraparound.
     autovacuum_max_workers                 | 3                                     | Sets the maximum number of simultaneously running autovacuum worker processes.
     autovacuum_multixact_freeze_max_age    | 400000000                             | Multixact age at which to autovacuum a table to prevent multixact wraparound.
     autovacuum_naptime                     | 1min                                  | Time to sleep between autovacuum runs.
     autovacuum_vacuum_cost_delay           | 20ms                                  | Vacuum cost delay in milliseconds, for autovacuum.
     autovacuum_vacuum_cost_limit           | -1                                    | Vacuum cost amount available before napping, for autovacuum.
     autovacuum_vacuum_scale_factor         | 0.2                                   | Number of tuple updates or deletes prior to vacuum as a fraction of reltuples.
     autovacuum_vacuum_threshold            | 50                                    | Minimum number of tuple updates or deletes prior to vacuum.
     autovacuum_work_mem                    | -1                                    | Sets the maximum memory to be used by each autovacuum worker process.
     backend_flush_after                    | 0                                     | Number of pages after which previously performed writes are flushed to disk.
     backslash_quote                        | safe_encoding                         | Sets whether "\'" is allowed in string literals.
     bgwriter_delay                         | 200ms                                 | Background writer sleep time between rounds.
     bgwriter_flush_after                   | 512kB                                 | Number of pages after which previously performed writes are flushed to disk.
     bgwriter_lru_maxpages                  | 100                                   | Background writer maximum number of LRU pages to flush per round.
     bgwriter_lru_multiplier                | 2                                     | Multiple of the average buffer usage to free per round.
     block_size                             | 8192                                  | Shows the size of a disk block.
     bonjour                                | off                                   | Enables advertising the server via Bonjour.
     bonjour_name                           |                                       | Sets the Bonjour service name.
     bytea_output                           | hex                                   | Sets the output format for bytea.
     check_function_bodies                  | on                                    | Check function bodies during CREATE FUNCTION.
     checkpoint_completion_target           | 0.5                                   | Time spent flushing dirty buffers during checkpoint, as fraction of checkpoint interval.
     checkpoint_flush_after                 | 256kB                                 | Number of pages after which previously performed writes are flushed to disk.
     checkpoint_timeout                     | 5min                                  | Sets the maximum time between automatic WAL checkpoints.
     checkpoint_warning                     | 30s                                   | Enables warnings if checkpoint segments are filled more frequently than this.
     client_encoding                        | UTF8                                  | Sets the client's character set encoding.
     client_min_messages                    | notice                                | Sets the message levels that are sent to the client.
     cluster_name                           |                                       | Sets the name of the cluster, which is included in the process title.
     commit_delay                           | 0                                     | Sets the delay in microseconds between transaction commit and flushing WAL to disk.
     commit_siblings                        | 5                                     | Sets the minimum concurrent open transactions before performing commit_delay.
     config_file                            | /mnt/hd2/data/postgresql.conf         | Sets the server's main configuration file.
     constraint_exclusion                   | partition                             | Enables the planner to use constraints to optimize queries.
     cpu_index_tuple_cost                   | 0.005                                 | Sets the planner's estimate of the cost of processing each index entry during an index scan.
     cpu_operator_cost                      | 0.0025                                | Sets the planner's estimate of the cost of processing each operator or function call.
     cpu_tuple_cost                         | 0.01                                  | Sets the planner's estimate of the cost of processing each tuple (row).
     cursor_tuple_fraction                  | 0.1                                   | Sets the planner's estimate of the fraction of a cursor's rows that will be retrieved.
     data_checksums                         | off                                   | Shows whether data checksums are turned on for this cluster.
     data_directory                         | /mnt/hd2/data                         | Sets the server's data directory.
     data_directory_mode                    | 0700                                  | Mode of the data directory.
     data_sync_retry                        | off                                   | Whether to continue running after a failure to sync data files.
     DateStyle                              | ISO, MDY                              | Sets the display format for date and time values.
     db_user_namespace                      | off                                   | Enables per-database user names.
     deadlock_timeout                       | 1s                                    | Sets the time to wait on a lock before checking for deadlock.
     debug_assertions                       | off                                   | Shows whether the running server has assertion checks enabled.
     debug_pretty_print                     | on                                    | Indents parse and plan tree displays.
     debug_print_parse                      | off                                   | Logs each query's parse tree.
     debug_print_plan                       | off                                   | Logs each query's execution plan.
     debug_print_rewritten                  | off                                   | Logs each query's rewritten parse tree.
     default_statistics_target              | 100                                   | Sets the default statistics target.
     default_tablespace                     |                                       | Sets the default tablespace to create tables and indexes in.
     default_text_search_config             | pg_catalog.english                    | Sets default text search configuration.
     default_transaction_deferrable         | off                                   | Sets the default deferrable status of new transactions.
     default_transaction_isolation          | read committed                        | Sets the transaction isolation level of each new transaction.
     default_transaction_read_only          | off                                   | Sets the default read-only status of new transactions.
     default_with_oids                      | off                                   | Create new tables with OIDs by default.
     dynamic_library_path                   | $libdir                               | Sets the path for dynamically loadable modules.
     dynamic_shared_memory_type             | posix                                 | Selects the dynamic shared memory implementation used.
     effective_cache_size                   | 4GB                                   | Sets the planner's assumption about the total size of the data caches.
     effective_io_concurrency               | 1                                     | Number of simultaneous requests that can be handled efficiently by the disk subsystem.
     enable_bitmapscan                      | on                                    | Enables the planner's use of bitmap-scan plans.
     enable_gathermerge                     | on                                    | Enables the planner's use of gather merge plans.
     enable_hashagg                         | on                                    | Enables the planner's use of hashed aggregation plans.
     enable_hashjoin                        | on                                    | Enables the planner's use of hash join plans.
     enable_indexonlyscan                   | on                                    | Enables the planner's use of index-only-scan plans.
     enable_indexscan                       | on                                    | Enables the planner's use of index-scan plans.
     enable_material                        | on                                    | Enables the planner's use of materialization.
     enable_mergejoin                       | on                                    | Enables the planner's use of merge join plans.
     enable_nestloop                        | on                                    | Enables the planner's use of nested-loop join plans.
     enable_parallel_append                 | on                                    | Enables the planner's use of parallel append plans.
     enable_parallel_hash                   | on                                    | Enables the planner's use of parallel hash plans.
     enable_partition_pruning               | on                                    | Enable plan-time and run-time partition pruning.
     enable_partitionwise_aggregate         | off                                   | Enables partitionwise aggregation and grouping.
     enable_partitionwise_join              | off                                   | Enables partitionwise join.
     enable_seqscan                         | on                                    | Enables the planner's use of sequential-scan plans.
     enable_sort                            | on                                    | Enables the planner's use of explicit sort steps.
     enable_tidscan                         | on                                    | Enables the planner's use of TID scan plans.
     escape_string_warning                  | on                                    | Warn about backslash escapes in ordinary string literals.
     event_source                           | PostgreSQL                            | Sets the application name used to identify PostgreSQL messages in the event log.
     exit_on_error                          | off                                   | Terminate session on any error.
     external_pid_file                      |                                       | Writes the postmaster PID to the specified file.
     extra_float_digits                     | 0                                     | Sets the number of digits displayed for floating-point values.
     force_parallel_mode                    | off                                   | Forces use of parallel query facilities.
     from_collapse_limit                    | 8                                     | Sets the FROM-list size beyond which subqueries are not collapsed.
     fsync                                  | on                                    | Forces synchronization of updates to disk.
     full_page_writes                       | on                                    | Writes full pages to WAL when first modified after a checkpoint.
     geqo                                   | on                                    | Enables genetic query optimization.
     geqo_effort                            | 5                                     | GEQO: effort is used to set the default for other GEQO parameters.
     geqo_generations                       | 0                                     | GEQO: number of iterations of the algorithm.
     geqo_pool_size                         | 0                                     | GEQO: number of individuals in the population.
     geqo_seed                              | 0                                     | GEQO: seed for random path selection.
     geqo_selection_bias                    | 2                                     | GEQO: selective pressure within the population.
     geqo_threshold                         | 12                                    | Sets the threshold of FROM items beyond which GEQO is used.
     gin_fuzzy_search_limit                 | 0                                     | Sets the maximum allowed result for exact search by GIN.
     gin_pending_list_limit                 | 4MB                                   | Sets the maximum size of the pending list for GIN index.
     hba_file                               | /mnt/hd2/data/pg_hba.conf             | Sets the server's "hba" configuration file.
     hot_standby                            | on                                    | Allows connections and queries during recovery.
     hot_standby_feedback                   | off                                   | Allows feedback from a hot standby to the primary that will avoid query conflicts.
     huge_pages                             | try                                   | Use of huge pages on Linux or Windows.
     ident_file                             | /mnt/hd2/data/pg_ident.conf           | Sets the server's "ident" configuration file.
     idle_in_transaction_session_timeout    | 0                                     | Sets the maximum allowed duration of any idling transaction.
     ignore_checksum_failure                | off                                   | Continues processing after a checksum failure.
     ignore_system_indexes                  | off                                   | Disables reading from system indexes.
     integer_datetimes                      | on                                    | Datetimes are integer based.
     IntervalStyle                          | postgres                              | Sets the display format for interval values.
     jit                                    | off                                   | Allow JIT compilation.
     jit_above_cost                         | 100000                                | Perform JIT compilation if query is more expensive.
     jit_debugging_support                  | off                                   | Register JIT compiled function with debugger.
     jit_dump_bitcode                       | off                                   | Write out LLVM bitcode to facilitate JIT debugging.
     jit_expressions                        | on                                    | Allow JIT compilation of expressions.
     jit_inline_above_cost                  | 500000                                | Perform JIT inlining if query is more expensive.
     jit_optimize_above_cost                | 500000                                | Optimize JITed functions if query is more expensive.
     jit_profiling_support                  | off                                   | Register JIT compiled function with perf profiler.
     jit_provider                           | llvmjit                               | JIT provider to use.
     jit_tuple_deforming                    | on                                    | Allow JIT compilation of tuple deforming.
     join_collapse_limit                    | 8                                     | Sets the FROM-list size beyond which JOIN constructs are not flattened.
     krb_caseins_users                      | off                                   | Sets whether Kerberos and GSSAPI user names should be treated as case-insensitive.
     krb_server_keyfile                     | FILE:/etc/sysconfig/pgsql/krb5.keytab | Sets the location of the Kerberos server key file.
     lc_collate                             | en_US.UTF-8                           | Shows the collation order locale.
     lc_ctype                               | en_US.UTF-8                           | Shows the character classification and case conversion locale.
     lc_messages                            | en_US.UTF-8                           | Sets the language in which messages are displayed.
     lc_monetary                            | en_US.UTF-8                           | Sets the locale for formatting monetary amounts.
     lc_numeric                             | en_US.UTF-8                           | Sets the locale for formatting numbers.
     lc_time                                | en_US.UTF-8                           | Sets the locale for formatting date and time values.
     listen_addresses                       | *                                     | Sets the host name or IP address(es) to listen to.
     lo_compat_privileges                   | off                                   | Enables backward compatibility mode for privilege checks on large objects.
     local_preload_libraries                |                                       | Lists unprivileged shared libraries to preload into each backend.
     lock_timeout                           | 0                                     | Sets the maximum allowed duration of any wait for a lock.
     log_autovacuum_min_duration            | -1                                    | Sets the minimum execution time above which autovacuum actions will be logged.
     log_checkpoints                        | off                                   | Logs each checkpoint.
     log_connections                        | off                                   | Logs each successful connection.
     log_destination                        | stderr                                | Sets the destination for server log output.
     log_directory                          | log                                   | Sets the destination directory for log files.
     log_disconnections                     | off                                   | Logs end of a session, including duration.
     log_duration                           | off                                   | Logs the duration of each completed SQL statement.
     log_error_verbosity                    | default                               | Sets the verbosity of logged messages.
     log_executor_stats                     | off                                   | Writes executor performance statistics to the server log.
     log_file_mode                          | 0600                                  | Sets the file permissions for log files.
     log_filename                           | postgresql-%a.log                     | Sets the file name pattern for log files.
     log_hostname                           | off                                   | Logs the host name in the connection logs.
     log_line_prefix                        | %m [%p]                               | Controls information prefixed to each log line.
     log_lock_waits                         | off                                   | Logs long lock waits.
     log_min_duration_statement             | -1                                    | Sets the minimum execution time above which statements will be logged.
     log_min_error_statement                | error                                 | Causes all statements generating error at or above this level to be logged.
     log_min_messages                       | warning                               | Sets the message levels that are logged.
     log_parser_stats                       | off                                   | Writes parser performance statistics to the server log.
     log_planner_stats                      | off                                   | Writes planner performance statistics to the server log.
     log_replication_commands               | off                                   | Logs each replication command.
     log_rotation_age                       | 1d                                    | Automatic log file rotation will occur after N minutes.
     log_rotation_size                      | 0                                     | Automatic log file rotation will occur after N kilobytes.
     log_statement                          | none                                  | Sets the type of statements logged.
     log_statement_stats                    | off                                   | Writes cumulative performance statistics to the server log.
     log_temp_files                         | -1                                    | Log the use of temporary files larger than this number of kilobytes.
     log_timezone                           | PRC                                   | Sets the time zone to use in log messages.
     log_truncate_on_rotation               | on                                    | Truncate existing log files of same name during log rotation.
     logging_collector                      | on                                    | Start a subprocess to capture stderr output and/or csvlogs into log files.
     maintenance_work_mem                   | 64MB                                  | Sets the maximum memory to be used for maintenance operations.
     max_connections                        | 100                                   | Sets the maximum number of concurrent connections.
     max_files_per_process                  | 1000                                  | Sets the maximum number of simultaneously open files for each server process.
     max_function_args                      | 100                                   | Shows the maximum number of function arguments.
     max_identifier_length                  | 63                                    | Shows the maximum identifier length.
     max_index_keys                         | 32                                    | Shows the maximum number of index keys.
     max_locks_per_transaction              | 64                                    | Sets the maximum number of locks per transaction.
     max_logical_replication_workers        | 4                                     | Maximum number of logical replication worker processes.
     max_parallel_maintenance_workers       | 2                                     | Sets the maximum number of parallel processes per maintenance operation.
     max_parallel_workers                   | 8                                     | Sets the maximum number of parallel workers that can be active at one time.
     max_parallel_workers_per_gather        | 2                                     | Sets the maximum number of parallel processes per executor node.
     max_pred_locks_per_page                | 2                                     | Sets the maximum number of predicate-locked tuples per page.
     max_pred_locks_per_relation            | -2                                    | Sets the maximum number of predicate-locked pages and tuples per relation.
     max_pred_locks_per_transaction         | 64                                    | Sets the maximum number of predicate locks per transaction.
     max_prepared_transactions              | 0                                     | Sets the maximum number of simultaneously prepared transactions.
     max_replication_slots                  | 10                                    | Sets the maximum number of simultaneously defined replication slots.
     max_stack_depth                        | 2MB                                   | Sets the maximum stack depth, in kilobytes.
     max_standby_archive_delay              | 30s                                   | Sets the maximum delay before canceling queries when a hot standby server is processing archived WAL data.
     max_standby_streaming_delay            | 30s                                   | Sets the maximum delay before canceling queries when a hot standby server is processing streamed WAL data.
     max_sync_workers_per_subscription      | 2                                     | Maximum number of table synchronization workers per subscription.
     max_wal_senders                        | 10                                    | Sets the maximum number of simultaneously running WAL sender processes.
     max_wal_size                           | 1GB                                   | Sets the WAL size that triggers a checkpoint.
     max_worker_processes                   | 8                                     | Maximum number of concurrent worker processes.
     min_parallel_index_scan_size           | 512kB                                 | Sets the minimum amount of index data for a parallel scan.
     min_parallel_table_scan_size           | 8MB                                   | Sets the minimum amount of table data for a parallel scan.
     min_wal_size                           | 80MB                                  | Sets the minimum size to shrink the WAL to.
     old_snapshot_threshold                 | -1                                    | Time before a snapshot is too old to read pages changed after the snapshot was taken.
     operator_precedence_warning            | off                                   | Emit a warning for constructs that changed meaning since PostgreSQL 9.4.
     parallel_leader_participation          | on                                    | Controls whether Gather and Gather Merge also run subplans.
     parallel_setup_cost                    | 1000                                  | Sets the planner's estimate of the cost of starting up worker processes for parallel query.
     parallel_tuple_cost                    | 0.1                                   | Sets the planner's estimate of the cost of passing each tuple (row) from worker to master backend.
     password_encryption                    | md5                                   | Encrypt passwords.
     port                                   | 5433                                  | Sets the TCP port the server listens on.
     post_auth_delay                        | 0                                     | Waits N seconds on connection startup after authentication.
     pre_auth_delay                         | 0                                     | Waits N seconds on connection startup before authentication.
     quote_all_identifiers                  | off                                   | When generating SQL fragments, quote all identifiers.
     random_page_cost                       | 4                                     | Sets the planner's estimate of the cost of a nonsequentially fetched disk page.
     restart_after_crash                    | on                                    | Reinitialize server after backend crash.
     row_security                           | on                                    | Enable row security.
     search_path                            | "$user", public                       | Sets the schema search order for names that are not schema-qualified.
     segment_size                           | 1GB                                   | Shows the number of pages per disk file.
     seq_page_cost                          | 1                                     | Sets the planner's estimate of the cost of a sequentially fetched disk page.
     server_encoding                        | UTF8                                  | Sets the server (database) character set encoding.
     server_version                         | 11.2                                  | Shows the server version.
     server_version_num                     | 110002                                | Shows the server version as an integer.
     session_preload_libraries              |                                       | Lists shared libraries to preload into each backend.
     session_replication_role               | origin                                | Sets the session's behavior for triggers and rewrite rules.
     shared_buffers                         | 128MB                                 | Sets the number of shared memory buffers used by the server.
     shared_preload_libraries               |                                       | Lists shared libraries to preload into server.
     ssl                                    | off                                   | Enables SSL connections.
     ssl_ca_file                            |                                       | Location of the SSL certificate authority file.
     ssl_cert_file                          | server.crt                            | Location of the SSL server certificate file.
     ssl_ciphers                            | HIGH:MEDIUM:+3DES:!aNULL              | Sets the list of allowed SSL ciphers.
     ssl_crl_file                           |                                       | Location of the SSL certificate revocation list file.
     ssl_dh_params_file                     |                                       | Location of the SSL DH parameters file.
     ssl_ecdh_curve                         | prime256v1                            | Sets the curve to use for ECDH.
     ssl_key_file                           | server.key                            | Location of the SSL server private key file.
     ssl_passphrase_command                 |                                       | Command to obtain passphrases for SSL.
     ssl_passphrase_command_supports_reload | off                                   | Also use ssl_passphrase_command during server reload.
     ssl_prefer_server_ciphers              | on                                    | Give priority to server ciphersuite order.
     standard_conforming_strings            | on                                    | Causes '...' strings to treat backslashes literally.
     statement_timeout                      | 0                                     | Sets the maximum allowed duration of any statement.
     stats_temp_directory                   | pg_stat_tmp                           | Writes temporary statistics files to the specified directory.
     superuser_reserved_connections         | 3                                     | Sets the number of connection slots reserved for superusers.
     synchronize_seqscans                   | on                                    | Enable synchronized sequential scans.
     synchronous_commit                     | on                                    | Sets the current transaction's synchronization level.
     synchronous_standby_names              |                                       | Number of synchronous standbys and list of names of potential synchronous ones.
     syslog_facility                        | local0                                | Sets the syslog "facility" to be used when syslog enabled.
     syslog_ident                           | postgres                              | Sets the program name used to identify PostgreSQL messages in syslog.
     syslog_sequence_numbers                | on                                    | Add sequence number to syslog messages to avoid duplicate suppression.
     syslog_split_messages                  | on                                    | Split messages sent to syslog by lines and to fit into 1024 bytes.
     tcp_keepalives_count                   | 0                                     | Maximum number of TCP keepalive retransmits.
     tcp_keepalives_idle                    | 0                                     | Time between issuing TCP keepalives.
     tcp_keepalives_interval                | 0                                     | Time between TCP keepalive retransmits.
     temp_buffers                           | 8MB                                   | Sets the maximum number of temporary buffers used by each session.
     temp_file_limit                        | -1                                    | Limits the total size of all temporary files used by each process.
     temp_tablespaces                       |                                       | Sets the tablespace(s) to use for temporary tables and sort files.
     TimeZone                               | PRC                                   | Sets the time zone for displaying and interpreting time stamps.
     timezone_abbreviations                 | Default                               | Selects a file of time zone abbreviations.
     trace_notify                           | off                                   | Generates debugging output for LISTEN and NOTIFY.
     trace_recovery_messages                | log                                   | Enables logging of recovery-related debugging information.
     trace_sort                             | off                                   | Emit information about resource usage in sorting.
     track_activities                       | on                                    | Collects information about executing commands.
     track_activity_query_size              | 1kB                                   | Sets the size reserved for pg_stat_activity.query, in bytes.
     track_commit_timestamp                 | off                                   | Collects transaction commit time.
     track_counts                           | on                                    | Collects statistics on database activity.
     track_functions                        | none                                  | Collects function-level statistics on database activity.
     track_io_timing                        | off                                   | Collects timing statistics for database I/O activity.
     transaction_deferrable                 | off                                   | Whether to defer a read-only serializable transaction until it can be executed with no possible serialization failures.
     transaction_isolation                  | read committed                        | Sets the current transaction's isolation level.
     transaction_read_only                  | off                                   | Sets the current transaction's read-only status.
     transform_null_equals                  | off                                   | Treats "expr=NULL" as "expr IS NULL".
     unix_socket_directories                | /var/run/postgresql, /tmp             | Sets the directories where Unix-domain sockets will be created.
     unix_socket_group                      |                                       | Sets the owning group of the Unix-domain socket.
     unix_socket_permissions                | 0777                                  | Sets the access permissions of the Unix-domain socket.
     update_process_title                   | on                                    | Updates the process title to show the active SQL command.
     vacuum_cleanup_index_scale_factor      | 0.1                                   | Number of tuple inserts prior to index cleanup as a fraction of reltuples.
     vacuum_cost_delay                      | 0                                     | Vacuum cost delay in milliseconds.
     vacuum_cost_limit                      | 200                                   | Vacuum cost amount available before napping.
     vacuum_cost_page_dirty                 | 20                                    | Vacuum cost for a page dirtied by vacuum.
     vacuum_cost_page_hit                   | 1                                     | Vacuum cost for a page found in the buffer cache.
     vacuum_cost_page_miss                  | 10                                    | Vacuum cost for a page not found in the buffer cache.
     vacuum_defer_cleanup_age               | 0                                     | Number of transactions by which VACUUM and HOT cleanup should be deferred, if any.
     vacuum_freeze_min_age                  | 50000000                              | Minimum age at which VACUUM should freeze a table row.
     vacuum_freeze_table_age                | 150000000                             | Age at which VACUUM should scan whole table to freeze tuples.
     vacuum_multixact_freeze_min_age        | 5000000                               | Minimum age at which VACUUM should freeze a MultiXactId in a table row.
     vacuum_multixact_freeze_table_age      | 150000000                             | Multixact age at which VACUUM should scan whole table to freeze tuples.
     wal_block_size                         | 8192                                  | Shows the block size in the write ahead log.
     wal_buffers                            | 4MB                                   | Sets the number of disk-page buffers in shared memory for WAL.
     wal_compression                        | off                                   | Compresses full-page writes written in WAL file.
     wal_consistency_checking               |                                       | Sets the WAL resource managers for which WAL consistency checks are done.
     wal_keep_segments                      | 0                                     | Sets the number of WAL files held for standby servers.
     wal_level                              | replica                               | Set the level of information written to the WAL.
     wal_log_hints                          | off                                   | Writes full pages to WAL when first modified after a checkpoint, even for a non-critical modifications.
     wal_receiver_status_interval           | 10s                                   | Sets the maximum interval between WAL receiver status reports to the primary.
     wal_receiver_timeout                   | 1min                                  | Sets the maximum wait time to receive data from the primary.
     wal_retrieve_retry_interval            | 5s                                    | Sets the time to wait before retrying to retrieve WAL after a failed attempt.
     wal_segment_size                       | 16MB                                  | Shows the size of write ahead log segments.
     wal_sender_timeout                     | 1min                                  | Sets the maximum time to wait for WAL replication.
     wal_sync_method                        | fdatasync                             | Selects the method used for forcing WAL updates to disk.
     wal_writer_delay                       | 200ms                                 | Time between WAL flushes performed in the WAL writer.
     wal_writer_flush_after                 | 1MB                                   | Amount of WAL written out by WAL writer that triggers a flush.
     work_mem                               | 4MB                                   | Sets the maximum memory to be used for query workspaces.
     xmlbinary                              | base64                                | Sets how binary values are to be encoded in XML.
     xmloption                              | content                               | Sets whether XML data in implicit parsing and serialization operations is to be considered as documents or content fragments.
     zero_damaged_pages                     | off                                   | Continues processing past damaged page headers.