1. 配置文件所在路径：
[postgres@kevin data]$ pwd /opt/postgresql/data [postgres@kevin data]$ ll 总用量 1332 drwx------ 8 postgres dba 4096 7月 13 10:50 base drwx------ 2 postgres dba 4096 7月 19 03:42 global -rw------- 1 postgres dba 1181357 7月 17 16:17 gmon.out drwx------ 159 postgres dba 4096 7月 19 03:44 gprof drwx------ 2 postgres dba 4096 7月 9 09:42 pg_clog -rw------- 1 postgres dba 3755 7月 9 14:54 pg_hba.conf -rw------- 1 postgres dba 1631 7月 9 09:42 pg_ident.conf drwx------ 4 postgres dba 4096 7月 9 09:42 pg_multixact drwx------ 2 postgres dba 4096 7月 19 05:57 pg_stat_tmp drwx------ 2 postgres dba 4096 7月 9 09:42 pg_subtrans drwx------ 2 postgres dba 4096 7月 13 10:54 pg_tblspc drwx------ 2 postgres dba 4096 7月 9 09:42 pg_twophase -rw------- 1 postgres dba 4 7月 9 09:42 PG_VERSION drwx------ 3 postgres dba 4096 7月 9 09:42 pg_xlog -rw------- 1 postgres dba 16837 7月 9 14:52 postgresql.conf -rw------- 1 postgres dba 16815 7月 9 14:51 postgresql.conf_duanyx_bak -rw------- 1 postgres dba 29 7月 19 03:42 postmaster.opts -rw------- 1 postgres dba 46 7月 19 03:42 postmaster.pid [postgres@kevin data]$
2. sql方式修改，可以在运行时设置，当然只有于部分选项，使用方法如下：
kevin_test=# SET work_mem = '16MB'; SET kevin_test=# kevin_test=# SELECT * FROM pg_settings WHERE source = 'session'; -[ RECORD 1 ]------------------------------------------------------------------- -------------------------------------------------- name | work_mem setting | 16384 unit | kB category | Resource Usage / Memory short_desc | Sets the maximum memory to be used for query workspaces. extra_desc | This much memory can be used by each internal sort operation and ha sh table before switching to temporary disk files. context | user vartype | integer source | session min_val | 64 max_val | 2097151 enumvals | boot_val | 1024 reset_val | 1024 sourcefile | sourceline | kevin_test=#
恢复默认设置的方法：
kevin_test=# RESET work_mem; RESET kevin_test=# SELECT * FROM pg_settings WHERE name = 'work_mem'; -[ RECORD 1 ]--------------------------------------------------------------------------------------------------------------------- name | work_mem setting | 1024 unit | kB category | Resource Usage / Memory short_desc | Sets the maximum memory to be used for query workspaces. extra_desc | This much memory can be used by each internal sort operation and hash table before switching to temporary disk files. context | user vartype | integer source | default min_val | 64 max_val | 2097151 enumvals | boot_val | 1024 reset_val | 1024 sourcefile | sourceline | kevin_test=#
3.查看配置项的值，当然你可以看接查看postgre.conf文件的内容，不过最好使用sql方法查看和修改，更为快速，当然你要先知道要查看的选项的名称。
kevin_test=# SHOW work_mem; work_mem ---------- 1MB (1 row) kevin_test=#
补充一下，如果确实不知道选项的名了，可以先查一下，这些均存储在pg_settings表中，呵呵，Postgresql的一个特点就在这，所有数据均由数据库自己维护。
kevin_test=# SELECT name,short_desc FROM pg_settings;
name | short_desc
---------------------------------+----------------------------------------------------------------------------------------------------------------------------
---
add_missing_from | Automatically adds missing table references to FROM clauses.
allow_system_table_mods | Allows modifications of the structure of system tables.
archive_command | Sets the shell command that will be called to archive a WAL file.
archive_mode | Allows archiving of WAL files using archive_command.
archive_timeout | Forces a switch to the next xlog file if a new file has not been started within N seconds.
array_nulls | Enable input of NULL elements in arrays.
authentication_timeout | Sets the maximum allowed time to complete client authentication.
autovacuum | Starts the autovacuum subprocess.
autovacuum_analyze_scale_factor | Number of tuple inserts,updates or deletes prior to analyze as a fraction of reltuples.
autovacuum_analyze_threshold | Minimum number of tuple inserts,updates or deletes prior to analyze.
autovacuum_freeze_max_age | Age at which to autovacuum a table to prevent transaction ID wraparound.
autovacuum_max_workers | Sets the maximum number of simultaneously running autovacuum worker processes.
autovacuum_naptime | Time to sleep between autovacuum runs.
autovacuum_vacuum_cost_delay | Vacuum cost delay in milliseconds,for autovacuum.
autovacuum_vacuum_cost_limit | Vacuum cost amount available before napping,for autovacuum.
autovacuum_vacuum_scale_factor | Number of tuple updates or deletes prior to vacuum as a fraction of reltuples.
autovacuum_vacuum_threshold | Minimum number of tuple updates or deletes prior to vacuum.
backslash_quote | Sets whether "\'" is allowed in string literals.
bgwriter_delay | Background writer sleep time between rounds.
bgwriter_lru_maxpages | Background writer maximum number of LRU pages to flush per round.
bgwriter_lru_multiplier | Multiple of the average buffer usage to free per round.
block_size | Shows the size of a disk block.
bonjour_name | Sets the Bonjour broadcast service name.
check_function_bodies | Check function bodies during CREATE FUNCTION.
checkpoint_completion_target | Time spent flushing dirty buffers during checkpoint,as fraction of checkpoint interval.
checkpoint_segments | Sets the maximum distance in log segments between automatic WAL checkpoints.
checkpoint_timeout | Sets the maximum time between automatic WAL checkpoints.
checkpoint_warning | Enables warnings if checkpoint segments are filled more frequently than this.
client_encoding | Sets the client's character set encoding.
client_min_messages | Sets the message levels that are sent to the client.
commit_delay | Sets the delay in microseconds between transaction commit and flushing WAL to disk.
commit_siblings | Sets the minimum concurrent open transactions before performing commit_delay.
config_file | Sets the server's main configuration file.
constraint_exclusion | Enables the planner to use constraints to optimize queries.
cpu_index_tuple_cost | Sets the planner's estimate of the cost of processing each index entry during an index scan.
cpu_operator_cost | Sets the planner's estimate of the cost of processing each operator or function call.
cpu_tuple_cost | Sets the planner's estimate of the cost of processing each tuple (row).
cursor_tuple_fraction | Sets the planner's estimate of the fraction of a cursor's rows that will be retrieved.
custom_variable_classes | Sets the list of known custom variable classes.
data_directory | Sets the server's data directory.
DateStyle | Sets the display format for date and time values.
db_user_namespace | Enables per-database user names.
deadlock_timeout | Sets the time to wait on a lock before checking for deadlock.
debug_assertions | Turns on varIoUs assertion checks.
debug_pretty_print | Indents parse and plan tree displays.
debug_print_parse | Logs each query's parse tree.
debug_print_plan | Logs each query's execution plan.
debug_print_rewritten | Logs each query's rewritten parse tree.
default_statistics_target | Sets the default statistics target.
default_tablespace | Sets the default tablespace to create tables and indexes in.
default_text_search_config | Sets default text search configuration.
default_transaction_isolation | Sets the transaction isolation level of each new transaction.
default_transaction_read_only | Sets the default read-only status of new transactions.
default_with_oids | Create new tables with OIDs by default.
dynamic_library_path | Sets the path for dynamically loadable modules.
effective_cache_size | Sets the planner's assumption about the size of the disk cache.
effective_io_concurrency | Number of simultaneous requests that can be handled efficiently by the disk subsystem.
enable_bitmapscan | Enables the planner's use of bitmap-scan plans.
enable_hashagg | Enables the planner's use of hashed aggregation plans.
enable_hashjoin | Enables the planner's use of hash join plans.
enable_indexscan | Enables the planner's use of index-scan plans.
enable_mergejoin | Enables the planner's use of merge join plans.
enable_nestloop | Enables the planner's use of nested-loop join plans.
enable_seqscan | Enables the planner's use of sequential-scan plans.
enable_sort | Enables the planner's use of explicit sort steps.
enable_tidscan | Enables the planner's use of TID scan plans.
escape_string_warning | Warn about backslash escapes in ordinary string literals.
external_pid_file | Writes the postmaster PID to the specified file.
extra_float_digits | Sets the number of digits displayed for floating-point values.
from_collapse_limit | Sets the FROM-list size beyond which subqueries are not collapsed.
fsync | Forces synchronization of updates to disk.
full_page_writes | Writes full pages to WAL when first modified after a checkpoint.
geqo | Enables genetic query optimization.
geqo_effort | GEQO: effort is used to set the default for other GEQO parameters.
geqo_generations | GEQO: number of iterations of the algorithm.
geqo_pool_size | GEQO: number of individuals in the population.
geqo_selection_bias | GEQO: selective pressure within the population.
geqo_threshold | Sets the threshold of FROM items beyond which GEQO is used.
gin_fuzzy_search_limit | Sets the maximum allowed result for exact search by GIN.
hba_file | Sets the server's "hba" configuration file.
ident_file | Sets the server's "ident" configuration file.
ignore_system_indexes | Disables reading from system indexes.
integer_datetimes | Datetimes are integer based.
IntervalStyle | Sets the display format for interval values.
join_collapse_limit | Sets the FROM-list size beyond which JOIN constructs are not flattened.
krb_caseins_users | Sets whether Kerberos and GSSAPI user names should be treated as case-insensitive.
krb_server_keyfile | Sets the location of the Kerberos server key file.
krb_srvname | Sets the name of the Kerberos service.
lc_collate | Shows the collation order locale.
lc_ctype | Shows the character classification and case conversion locale.
lc_messages | Sets the language in which messages are displayed.
lc_monetary | Sets the locale for formatting monetary amounts.
lc_numeric | Sets the locale for formatting numbers.
lc_time | Sets the locale for formatting date and time values.
listen_addresses | Sets the host name or IP address(es) to listen to.
local_preload_libraries | Lists shared libraries to preload into each backend.
log_autovacuum_min_duration | Sets the minimum execution time above which autovacuum actions will be logged.
log_checkpoints | Logs each checkpoint.
log_connections | Logs each successful connection.
log_destination | Sets the destination for server log output.
log_directory | Sets the destination directory for log files.
log_disconnections | Logs end of a session,including duration.
log_duration | Logs the duration of each completed sql statement.
log_error_verbosity | Sets the verbosity of logged messages.
log_executor_stats | Writes executor performance statistics to the server log.
log_filename | Sets the file name pattern for log files.
log_hostname | Logs the host name in the connection logs.
log_line_prefix | Controls information prefixed to each log line.
log_lock_waits | Logs long lock waits.
log_min_duration_statement | Sets the minimum execution time above which statements will be logged.
log_min_error_statement | Causes all statements generating error at or above this level to be logged.
log_min_messages | Sets the message levels that are logged.
log_parser_stats | Writes parser performance statistics to the server log.
log_planner_stats | Writes planner performance statistics to the server log.
log_rotation_age | Automatic log file rotation will occur after N minutes.
log_rotation_size | Automatic log file rotation will occur after N kilobytes.
log_statement | Sets the type of statements logged.
log_statement_stats | Writes cumulative performance statistics to the server log.
log_temp_files | Log the use of temporary files larger than this number of kilobytes.
log_timezone | Sets the time zone to use in log messages.
log_truncate_on_rotation | Truncate existing log files of same name during log rotation.
logging_collector | Start a subprocess to capture stderr output and/or csvlogs into log files.
maintenance_work_mem | Sets the maximum memory to be used for maintenance operations.
max_connections | Sets the maximum number of concurrent connections.
max_files_per_process | Sets the maximum number of simultaneously open files for each server process.
max_function_args | Shows the maximum number of function arguments.
max_identifier_length | Shows the maximum identifier length.
max_index_keys | Shows the maximum number of index keys.
max_locks_per_transaction | Sets the maximum number of locks per transaction.
max_prepared_transactions | Sets the maximum number of simultaneously prepared transactions.
max_stack_depth | Sets the maximum stack depth,in kilobytes.
password_encryption | Encrypt passwords.
port | Sets the TCP port the server listens on.
post_auth_delay | Waits N seconds on connection startup after authentication.
pre_auth_delay | Waits N seconds on connection startup before authentication.
random_page_cost | Sets the planner's estimate of the cost of a nonsequentially fetched disk page.
regex_flavor | Sets the regular expression "flavor".
search_path | Sets the schema search order for names that are not schema-qualified.
segment_size | Shows the number of pages per disk file.
seq_page_cost | Sets the planner's estimate of the cost of a sequentially fetched disk page.
server_encoding | Sets the server (database) character set encoding.
server_version | Shows the server version.
server_version_num | Shows the server version as an integer.
session_replication_role | Sets the session's behavior for triggers and rewrite rules.
shared_buffers | Sets the number of shared memory buffers used by the server.
shared_preload_libraries | Lists shared libraries to preload into server.
silent_mode | Runs the server silently.
sql_inheritance | Causes subtables to be included by default in varIoUs commands.
ssl | Enables SSL connections.
standard_conforming_strings | Causes '...' strings to treat backslashes literally.
statement_timeout | Sets the maximum allowed duration of any statement.
stats_temp_directory | Writes temporary statistics files to the specified directory.
superuser_reserved_connections | Sets the number of connection slots reserved for superusers.
synchronize_seqscans | Enable synchronized sequential scans.
synchronous_commit | Sets immediate fsync at commit.
syslog_facility | Sets the syslog "facility" to be used when syslog enabled.
syslog_ident | Sets the program name used to identify Postgresql messages in syslog.
tcp_keepalives_count | Maximum number of TCP keepalive retransmits.
tcp_keepalives_idle | Time between issuing TCP keepalives.
tcp_keepalives_interval | Time between TCP keepalive retransmits.
temp_buffers | Sets the maximum number of temporary buffers used by each session.
temp_tablespaces | Sets the tablespace(s) to use for temporary tables and sort files.
TimeZone | Sets the time zone for displaying and interpreting time stamps.
timezone_abbreviations | Selects a file of time zone abbreviations.
trace_notify | Generates debugging output for LISTEN and NOTIFY.
trace_sort | Emit information about resource usage in sorting.
track_activities | Collects information about executing commands.
track_activity_query_size | Sets the size reserved for pg_stat_activity.current_query,in bytes.
track_counts | Collects statistics on database activity.
track_functions | Collects function-level statistics on database activity.
transaction_isolation | Sets the current transaction's isolation level.
transaction_read_only | Sets the current transaction's read-only status.
transform_null_equals | Treats "expr=NULL" as "expr IS NULL".
unix_socket_directory | Sets the directory where the Unix-domain socket will be created.
unix_socket_group | Sets the owning group of the Unix-domain socket.
unix_socket_permissions | Sets the access permissions of the Unix-domain socket.
update_process_title | Updates the process title to show the active sql command.
vacuum_cost_delay | Vacuum cost delay in milliseconds.
vacuum_cost_limit | Vacuum cost amount available before napping.
vacuum_cost_page_dirty | Vacuum cost for a page dirtied by vacuum.
vacuum_cost_page_hit | Vacuum cost for a page found in the buffer cache.
vacuum_cost_page_miss | Vacuum cost for a page not found in the buffer cache.
vacuum_freeze_min_age | Minimum age at which VACUUM should freeze a table row.
vacuum_freeze_table_age | Age at which VACUUM should scan whole table to freeze tuples.
wal_block_size | Shows the block size in the write ahead log.
wal_buffers | Sets the number of disk-page buffers in shared memory for WAL.
wal_segment_size | Shows the number of pages per write ahead log segment.
wal_sync_method | Selects the method used for forcing WAL updates to disk.
wal_writer_delay | WAL writer sleep time between WAL flushes.
work_mem | Sets the maximum memory to be used for query workspaces.
xmlbinary | Sets how binary values are to be encoded in XML.
xmloption | Sets whether XML data in implicit parsing and serialization operations is to be considered as documents or content fragment
s.
zero_damaged_pages | Continues processing past damaged page headers.
(193 rows)
kevin_test=#
4.记住选项值的改动并不一定对整个数据库生效，有时仅对当前session在效，在执行SET语句时，可通过LOCAL选项明确指定。
kevin_test=# SET LOCAL work_mem='16MB'; SET kevin_test=#
5.查看系统中哪些选项被修改过。
kevin_test=# SELECT name,source,setting FROM pg_settings
WHERE source != 'default'
AND source != 'override'
ORDER BY 2,1;
name | source | setting
----------------------------+----------------------+-------------------
log_timezone | command line | PRC
TimeZone | command line | PRC
timezone_abbreviations | command line | Default
DateStyle | configuration file | ISO,YMD
default_text_search_config | configuration file | pg_catalog.simple
lc_messages | configuration file | zh_CN.UTF-8
lc_monetary | configuration file | zh_CN.UTF-8
lc_numeric | configuration file | zh_CN.UTF-8
lc_time | configuration file | zh_CN.UTF-8
listen_addresses | configuration file | *
max_connections | configuration file | 100
shared_buffers | configuration file | 3584
max_stack_depth | environment variable | 2048
(13 rows)
kevin_test=#
