| There are a lot of configuration parameters that affect the
behavior of the database system. In this subsection, we describe
how to set configuration parameters; the following subsections
discuss each parameter in detail.
All parameter names are case-insensitive. Every parameter takes a
value of one of the four types: boolean, integer, floating point,
and string. Boolean values are ON,
OFF, TRUE,
FALSE, YES,
NO, 1, 0
(case-insensitive) or any non-ambiguous prefix of these.
One way to set these parameters is to edit the file
postgresql.conf
in the data directory. (A default file is installed there.) An
example of what this file might look like is:
# This is a comment
log_connections = yes
log_destination = 'syslog'
search_path = '$user, public'
One parameter is specified per line. The equal sign between name and
value is optional. Whitespace is insignificant and blank lines are
ignored. Hash marks (#) introduce comments
anywhere. Parameter values that are not simple identifiers or
numbers should be single-quoted.
The configuration file is reread whenever the
edb-postmaster process receives a
SIGHUP signal (which is most easily sent by means
of pg_ctl reload). The edb-postmaster
also propagates this signal to all currently running server
processes so that existing sessions also get the new
value. Alternatively, you can send the signal to a single server
process directly. Some parameters can only be set at server start;
any changes to their entries in the configuration file will be ignored
until the server is restarted.
A second way to set these configuration parameters is to give them
as a command line option to the edb-postmaster, such as:
edb-postmaster -c log_connections=yes -c log_destination='syslog'
Command-line options override any conflicting settings in
postgresql.conf.
Occasionally it is also useful to give a command line option to
one particular session only. The environment variable
PGOPTIONS can be used for this purpose on the
client side:
env PGOPTIONS='-c geqo=off' edb-psql
Note that this won't work for
parameters that are fixed when the server is started, nor for
parameters that require superuser permissions to change (not even
if you are logging in as superuser).
Furthermore, it is possible to assign a set of option settings to
a user or a database. Whenever a session is started, the default
settings for the user and database involved are loaded. The
commands ALTER DATABASE and ALTER USER,
respectively, are used to configure these settings. Per-database
settings override anything received from the
edb-postmaster command-line or the configuration
file, and in turn are overridden by per-user settings; both are
overridden by per-session options.
Some parameters can be changed in individual SQL
sessions with the SET
command, for example:
SET ENABLE_SEQSCAN TO OFF;
If SET is allowed, it overrides all other sources of
values for the parameter. Some parameters cannot be changed via
SET: for example, if they control behavior that
cannot reasonably be changed without restarting
EnterpriseDB. Also, some parameters can
be modified via SET by superusers, but not by
ordinary users.
- data_directory (string)
Specifies the directory to use for data storage.
This option can only be set at server start.
- config_file (string)
Specifies the main server configuration file
(customarily called postgresql.conf).
This option can only be set on the edb-postmaster command line.
- hba_file (string)
Specifies the configuration file for host-based authentication.
This option can only be set at server start.
- ident_file (string)
Specifies the configuration file for
ident authentication.
This option can only be set at server start.
- external_pid_file (string)
Specifies that the edb-postmaster should create an
additional process-id (PID) file for use by server administration
programs.
This option can only be set at server start.
In a default installation, none of the above options is set explicitly
in the postgresql.conf file. Instead, the
data directory is specified by the -D command-line
option or the PGDATA environment variable, and the
configuration files are all placed within the data directory.
It is also possible to separate the configuration files from the data
directory, which can ease administration. (In particular it is often
easier to ensure that the configuration files are properly backed-up
when they are kept separate.) To do this, the -D
command-line option or PGDATA environment variable
must point to the directory containing the configuration files,
and the data_directory option is set in
postgresql.conf (or on the command line) to show
where the data directory is actually located. Notice that
data_directory overrides -D for the location
of the data directory, but not for the location of the configuration
files.
If you wish, you can specify the configuration file names and locations
individually using the options config_file,
hba_file and/or ident_file.
config_file can only be specified on the
edb-postmaster command line, but the others can be
set within the main configuration file. If all three options plus
data_directory are explicitly set, then it is not necessary
to specify -D or PGDATA .
When setting any of these options, a relative path will be interpreted
with respect to the directory in which the edb-postmaster
is started.
- listen_addresses (string)
Specifies the TCP/IP address(es) on which the server is
to listen for connections from client applications.
The value takes the form of a comma-separated list of host names
and/or numeric IP addresses. The special entry *
corresponds to all available IP interfaces.
If the list is empty, the server does not listen on any IP interface
at all, in which case only Unix-domain sockets can be used to connect
to it.
The default value is localhost,
which allows only local "loopback" connections to be made.
This parameter can only be set at server start.
- port (integer)
The TCP port the server listens on; 5444 by default. Note that the
same port number is used for all IP addresses the server listens on.
This parameter can only be set at server start.
- max_connections (integer)
Determines the maximum number of concurrent connections to the
database server. The default is typically 100, but may be less
if your kernel settings will not support it (as determined
during initdb). This parameter can only be
set at server start.
Increasing this parameter may cause EnterpriseDB
to request more System V shared
memory or semaphores than your operating system's default configuration
allows. See Section 30.5.1 for information on how to
adjust those parameters, if necessary.
- superuser_reserved_connections
(integer)
Determines the number of "connection slots" that
are reserved for connections by EnterpriseDB
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 default value is 2. The value must be less than the value of
max_connections. This parameter can only be
set at server start.
- unix_socket_directory (string)
Specifies the directory of the Unix-domain socket on which the
server is to listen for
connections from client applications. The default is normally
/tmp, but can be changed at build time.
This parameter can only be set at server start.
- unix_socket_group (string)
Sets the owning group of the Unix-domain socket. (The owning
user of the socket is always the user that starts the
server.) In combination with the option
unix_socket_permissions this can be used as
an additional access control mechanism for Unix-domain connections.
By default this is the empty string, which uses the default
group for the current user. This option can only be set at
server start.
- unix_socket_permissions (integer)
Sets the access permissions of the Unix-domain socket. Unix
domain sockets use the usual Unix file system permission set.
The option value is expected to be a numeric mode
specification in the form accepted by the
chmod and umask
system calls. (To use the customary octal format the number
must start with a 0 (zero).)
The default permissions are 0777, meaning
anyone can connect. Reasonable alternatives are
0770 (only user and group, see also
unix_socket_group) and 0700
(only user). (Note that actually for a Unix domain socket, only write
permission matters and there is no point in setting or revoking
read or execute permissions.)
This access control mechanism is independent of the one
described in Chapter 33.
This option can only be set at server start.
- bonjour_name (string)
Specifies the bonjour broadcast
name. By default, the computer name is used, specified as an
empty string ''. This option is only meaningful on platforms
that support bonjour. This
option can only be set at server start.
- tcp_keepalives_idle (integer)
On systems that support the TCP_KEEPIDLE socket option, specifies the
number of seconds between sending keepalives on an otherwise idle
connection. A value of 0 uses the system default. If TCP_KEEPIDLE is
not supported, this parameter must be 0. This option is ignored for
connections made via a Unix-domain socket.
- tcp_keepalives_interval (integer)
On systems that support the TCP_KEEPINTVL socket option, specifies how
long, in seconds, to wait for a response to a keepalive before
retransmitting. A value of 0 uses the system default. If TCP_KEEPINTVL
is not supported, this parameter must be 0. This option is ignored
for connections made via a Unix-domain socket.
- tcp_keepalives_count (integer)
On systems that support the TCP_KEEPCNT socket option, specifies how
many keepalives may be lost before the connection is considered dead.
A value of 0 uses the system default. If TCP_KEEPCNT is not
supported, this parameter must be 0. This option is ignored
for connections made via a Unix-domain socket.
- authentication_timeout (integer)
Maximum time to complete client authentication, in seconds. If a
would-be client has not completed the authentication protocol in
this much time, the server breaks the connection. This prevents
hung clients from occupying a connection indefinitely. This
option can only be set at server start or in the
postgresql.conf file. The default is 60.
- ssl (boolean)
Enables SSL connections. The default
is off. This parameter can only be set at server start.
- password_encryption (boolean)
When a password is specified in CREATE USER or
ALTER USER
without writing either ENCRYPTED or
UNENCRYPTED, this option determines whether the
password is to be encrypted. The default is on (encrypt the
password).
- krb_server_keyfile (string)
Sets the location of the Kerberos server key file. See
Section 33.2.3 for details. This parameter can only
be set at server start time.
- krb_srvname (string)
Sets the Kerberos service name. See Section 33.2.3
for details. This parameter can only be set at server start.
- krb_server_hostname (string)
Sets the host name part of the service principal.
This, combined with krb_srvname, is used to generate
the complete service principal, that is
krb_srvname/krb_server_hostname@REALM.
If not set, the default is the server host name. See Section 33.2.3
for details. This parameter can only be set at server start.
- krb_caseins_users (boolean)
Sets whether Kerberos user names should be treated case-insensitively.
The default is off (case sensitive). This parameter
can only be set at server start.
- db_user_namespace (boolean)
This allows per-database user names. It is off by default.
If this is on, you should create users as username@dbname.
When username is passed by a connecting client,
@ and the database name is appended to the user
name and that database-specific user name is looked up by the
server. Note that when you create users with names containing
@ within the SQL environment, you will need to
quote the user name.
With this option enabled, you can still create ordinary global
users. Simply append @ when specifying the user
name in the client. The @ will be stripped off
before the user name is looked up by the server.
Note: This feature is intended as a temporary measure until a
complete solution is found. At that time, this option will
be removed.
EnterpriseDB provides a single configuration parameter than can be set
in accordance with the intended use of the host system in order to provide the maximum performance out of
EnterpriseDB on that particular machine.
The description of this configuration parameter follows.
- edb_dynatune (integer)
Sets the resources used by EnterpriseDB in accordance with the intended purpose
and capacity of the host machine on which the EnterpriseDB database server is installed.
An integer value is specified in the range of 1 thru 100 that describes
on a relative basis, the amount of resources to be dedicated to the EnterpriseDB
database server. The smaller the value, the smaller the amount of the
host system's resources will be dedicated to EnterpriseDB allowing more applications
to share the same machine. The larger the value, the larger the amount of
the host machine's resources will be dedicated to EnterpriseDB providing for best
database performance.
- shared_buffers (integer)
Sets the number of shared memory buffers used by the database
server. The default is typically 1000, but may be less if your
kernel settings will not support it (as determined during
initdb). Each buffer is 8192 bytes, unless a
different value of BLCKSZ was chosen when building
the server. This setting must be at least 16, as well as at
least twice the value of max_connections;
however, settings significantly higher than the minimum are
usually needed for good performance. Values of a few thousand
are recommended for production installations. This option can
only be set at server start.
Increasing this parameter may cause EnterpriseDB
to request more System V shared
memory than your operating system's default configuration
allows. See Section 30.5.1 for information on how to
adjust those parameters, if necessary.
- temp_buffers (integer)
Sets the maximum number of temporary buffers used by each database
session. These are session-local buffers used only for access
to temporary tables. The default is 1000. The setting can
be changed within individual sessions, but only up until the
first use of temporary tables within a session; subsequent
attempts to change the value will have no effect on that session.
A session will allocate temporary buffers as needed up to the limit
given by temp_buffers. The cost of setting a large
value in sessions that do not actually need a lot of temporary
buffers is only a buffer descriptor, or about 64 bytes, per
increment in temp_buffers. However if a buffer is
actually used an additional 8192 bytes will be consumed for it
(or in general, BLCKSZ bytes).
- max_prepared_transactions (integer)
Sets the maximum number of transactions that can be in the
"prepared" state simultaneously (see PREPARE TRANSACTION).
Setting this parameter to zero disables the prepared-transaction
feature.
The default is 5.
This option can only be set at server start.
If you are not using prepared transactions, this parameter may as
well be set to zero. If you are using them, you will probably
want max_prepared_transactions to be at least
as large as max_connections, to avoid unwanted
failures at the prepare step.
Increasing this parameter may cause EnterpriseDB
to request more System V shared
memory than your operating system's default configuration
allows. See Section 30.5.1 for information on how to
adjust those parameters, if necessary.
- work_mem (integer)
Specifies the amount of memory to be used by internal sort operations
and hash tables before switching to temporary disk files. The value is
specified in kilobytes, and defaults to 1024 kilobytes (1 MB).
Note that for a complex query, several sort or hash operations might be
running in parallel; each one will be allowed to use as much memory
as this value specifies before it starts to put data into temporary
files. Also, several running sessions could be doing such operations
concurrently. So the total memory used could be many
times the value of work_mem; it is necessary to
keep this fact in mind when choosing the value. Sort operations are
used for ORDER BY, DISTINCT, and
merge joins.
Hash tables are used in hash joins, hash-based aggregation, and
hash-based processing of IN subqueries.
- maintenance_work_mem (integer)
Specifies the maximum amount of memory to be used in maintenance
operations, such as VACUUM, CREATE
INDEX, and ALTER TABLE ADD FOREIGN KEY.
The value is specified in kilobytes, and defaults to 16384 kilobytes
(16 MB). Since only one of these operations can be executed at
a time by a database session, and an installation normally doesn't
have very many of them happening concurrently, it's safe to set this
value significantly larger than work_mem. Larger
settings may improve performance for vacuuming and for restoring
database dumps.
- max_stack_depth (integer)
Specifies the maximum safe depth of the server's execution stack.
The ideal setting for this parameter is the actual stack size limit
enforced by the kernel (as set by ulimit -s or local
equivalent), less a safety margin of a megabyte or so. The safety
margin is needed because the stack depth is not checked in every
routine in the server, but only in key potentially-recursive routines
such as expression evaluation. Setting the parameter higher than
the actual kernel limit will mean that a runaway recursive function
can crash an individual backend process. The default setting is
2048 KB (two megabytes), which is conservatively small and unlikely
to risk crashes. However, it may be too small to allow execution
of complex functions.
These parameters control the size of the shared free space
map, which
tracks the location of unused space in the database. An undersized free
space map may cause the database to consume increasing amounts of disk
space over time, because the free space that is not in the map cannot be
re-used;instead EnterpriseDB will request
more disk space from the operating system when it needs to store new
data. The last few lines displayed by a database-wise
VACUUM VERBOSE command can help in determining if the
current settings are adequate. A NOTICE message is
also printed during such an operation if the current settings are too
low.
Increasing these parameters may cause
EnterpriseDB to request more System V shared
memory than your operating system's default configuration allows.
- max_fsm_pages (integer)
Sets the maximum number of disk pages for which free space will
be tracked in the shared free-space map. Six bytes of shared memory
are consumed for each page slot. This setting must be more than
16 * max_fsm_relations. The default is 20000.
This option can only be set at server start.
- max_fsm_relations (integer)
Sets the maximum number of relations (tables and indexes) for which
free space will be tracked in the shared free-space map. Roughly
fifty bytes of shared memory are consumed for each slot.
The default is 1000.
This option can only be set at server start.
- max_files_per_process (integer)
Sets the maximum number of simultaneously open files allowed to each
server subprocess. The default is 1000. If the kernel is enforcing
a safe per-process limit, you don't need to worry about this setting.
But on some platforms (notably, most BSD systems), the kernel will
allow individual processes to open many more files than the system
can really support when a large number of processes all try to open
that many files. If you find yourself seeing "Too many open
files" failures, try reducing this setting.
This option can only be set at server start.
- preload_libraries (string)
This variable specifies one or more shared libraries that are
to be preloaded at server start. A parameterless
initialization function can optionally be called for each
library. To specify that, add a colon and the name of the
initialization function after the library name. For example
'$libdir/mylib:mylib_init' would cause
mylib to be preloaded and mylib_init
to be executed. If more than one library is to be loaded,
separate their names with commas.
If mylib or mylib_init are not found, the
server will fail to start.
EnterpriseDB procedural language
libraries may be preloaded in this way, typically by using the
syntax '$libdir/plXXX:plXXX_init' where
XXX is pgsql, perl,
tcl, or python.
By preloading a shared library (and initializing it if
applicable), the library startup time is avoided when the
library is first used. However, the time to start each new
server process may increase, even if that process never
uses the library.
During the execution of VACUUM and ANALYZE commands, the system maintains an
internal counter that keeps track of the estimated cost of the
various I/O operations that are performed. When the accumulated
cost reaches a limit (specified by
vacuum_cost_limit), the process performing
the operation will sleep for a while (specified by
vacuum_cost_delay). Then it will reset the
counter and continue execution.
The intent of this feature is to allow administrators to reduce
the I/O impact of these commands on concurrent database
activity. There are many situations in which it is not very
important that maintenance commands like
VACUUM and ANALYZE finish
quickly; however, it is usually very important that these
commands do not significantly interfere with the ability of the
system to perform other database operations. Cost-based vacuum
delay provides a way for administrators to achieve this.
This feature is disabled by default. To enable it, set the
vacuum_cost_delay variable to a nonzero
value.
- vacuum_cost_delay (integer)
The length of time, in milliseconds, that the process will sleep
when the cost limit has been exceeded.
The default value is 0, which disables the cost-based vacuum
delay feature. Positive values enable cost-based vacuuming.
Note that on many systems, the effective resolution
of sleep delays is 10 milliseconds; setting
vacuum_cost_delay to a value that is
not a multiple of 10 may have the same results as setting it
to the next higher multiple of 10.
- vacuum_cost_page_hit (integer)
The estimated cost for vacuuming a buffer found in the shared buffer
cache. It represents the cost to lock the buffer pool, lookup
the shared hash table and scan the content of the page. The
default value is 1.
- vacuum_cost_page_miss (integer)
The estimated cost for vacuuming a buffer that has to be read from
disk. This represents the effort to lock the buffer pool,
lookup the shared hash table, read the desired block in from
the disk and scan its content. The default value is 10.
- vacuum_cost_page_dirty (integer)
The estimated cost charged when vacuum modifies a block that was
previously clean. It represents the extra I/O required to
flush the dirty block out to disk again. The default value is
20.
- vacuum_cost_limit (integer)
The accumulated cost that will cause the vacuuming process to sleep.
The default value is 200.
Note: There are certain operations that hold critical locks and should
therefore complete as quickly as possible. Cost-based vacuum
delays do not occur during such operations. Therefore it is
possible that the cost accumulates far higher than the specified
limit. To avoid uselessly long delays in such cases, the actual
delay is calculated as vacuum_cost_delay *
accumulated_balance /
vacuum_cost_limit with a maximum of
vacuum_cost_delay * 4.
EnterpriseDB has a separate server process called the background writer,
whose sole function
is to issue writes of "dirty" shared buffers. The intent is
that server processes handling user queries should seldom or never have
to wait for a write to occur, because the background writer will do it.
This arrangement also reduces the performance penalty associated with
checkpoints. The background writer will continuously trickle out dirty
pages to disk, so that only a few pages will need to be forced out when
checkpoint time arrives, instead of the storm of dirty-buffer writes that
formerly occurred at each checkpoint. However there is a net overall
increase in I/O load, because where a repeatedly-dirtied page might
before have been written only once per checkpoint interval, the
background writer might write it several times in the same interval.
In most situations a continuous low load is preferable to periodic
spikes, but the parameters discussed in this section can be used to tune
the behavior for local needs.
- bgwriter_delay (integer)
Specifies the delay between activity rounds for the
background writer. In each round the writer issues writes
for some number of dirty buffers (controllable by the
following parameters). The selected buffers will always be
the least recently used ones among the currently dirty
buffers. It then sleeps for bgwriter_delay
milliseconds, and repeats. The default value is 200. Note
that on many systems, the effective resolution of sleep
delays is 10 milliseconds; setting bgwriter_delay
to a value that is not a multiple of 10 may have the same
results as setting it to the next higher multiple of 10.
This option can only be set at server start or in the
postgresql.conf file.
- bgwriter_lru_percent (floating point)
To reduce the probability that server processes will need to issue
their own writes, the background writer tries to write buffers that
are likely to be recycled soon. In each round, it examines up to
bgwriter_lru_percent of the buffers that are nearest to
being recycled, and writes any that are dirty.
The default value is 1.0 (this is a percentage of the total number
of shared buffers).
This option can only be set at server start or in the
postgresql.conf file.
- bgwriter_lru_maxpages (integer)
In each round, no more than this many buffers will be written
as a result of scanning soon-to-be-recycled buffers.
The default value is 5.
This option can only be set at server start or in the
postgresql.conf file.
- bgwriter_all_percent (floating point)
To reduce the amount of work that will be needed at checkpoint time,
the background writer also does a circular scan through the entire
buffer pool, writing buffers that are found to be dirty.
In each round, it examines up to
bgwriter_all_percent of the buffers for this purpose.
The default value is 0.333 (this is a percentage of the total number
of shared buffers). With the default bgwriter_delay
setting, this will allow the entire shared buffer pool to be scanned
about once per minute.
This option can only be set at server start or in the
postgresql.conf file.
- bgwriter_all_maxpages (integer)
In each round, no more than this many buffers will be written
as a result of the scan of the entire buffer pool. (If this
limit is reached, the scan stops, and resumes at the next buffer
during the next round.)
The default value is 5.
This option can only be set at server start or in the
postgresql.conf file.
Smaller values of bgwriter_all_percent and
bgwriter_all_maxpages reduce the extra I/O load
caused by the background writer, but leave more work to be done
at checkpoint time. To reduce load spikes at checkpoints,
increase these two values.
Similarly, smaller values of bgwriter_lru_percent and
bgwriter_lru_maxpages reduce the extra I/O load
caused by the background writer, but make it more likely that server
processes will have to issue writes for themselves, delaying interactive
queries.
To disable background writing entirely,
set both maxpages values and/or both
percent values to zero.
See also Section 39.2 for details on WAL
tuning.
- fsync (boolean)
If this option is on, the EnterpriseDB server
will use the fsync() system call in several places
to make sure that updates are physically written to disk. This
insures that a database cluster will recover to a
consistent state after an operating system or hardware crash.
However, using fsync() results in a
performance penalty: when a transaction is committed,
EnterpriseDB must wait for the
operating system to flush the write-ahead log to disk. When
fsync is disabled, the operating system is
allowed to do its best in buffering, ordering, and delaying
writes. This can result in significantly improved performance.
However, if the system crashes, the results of the last few
committed transactions may be lost in part or whole. In the
worst case, unrecoverable data corruption may occur.
(Crashes of the database server itself are not
a risk factor here. Only an operating-system-level crash
creates a risk of corruption.)
Due to the risks involved, there is no universally correct
setting for fsync. Some administrators
always disable fsync, while others only
turn it off for bulk loads, where there is a clear restart
point if something goes wrong, whereas some administrators
always leave fsync enabled. The default is
to enable fsync, for maximum reliability.
If you trust your operating system, your hardware, and your
utility company (or your battery backup), you can consider
disabling fsync.
This option can only be set at server start or in the
postgresql.conf file.
- wal_sync_method (string)
Method used for forcing WAL updates out to disk. Possible
values are:
open_datasync (write WAL files with open() option O_DSYNC).
fdatasync (call fdatasync() at each
commit).
fsync_writethrough (call fsync() at
each commit, forcing write-through of any disk write cache).
fsync (call fsync() at each commit).
open_sync (write WAL files with
open() option O_SYNC).
Not all of these choices are available on all platforms.
If fsync is off then this setting is irrelevant.
This option can only be set at server start or in the
postgresql.conf file.
- full_page_writes (boolean)
When this option is on, the EnterpriseDB server
writes the entire content of each disk page to WAL during the
first modification of that page after a checkpoint.
This is needed because
a page write that is in process during an operating system crash might
be only partially completed, leading to an on-disk page
that contains a mix of old and new data. The row-level change data
normally stored in WAL will not be enough to completely restore
such a page during post-crash recovery. Storing the full page image
guarantees that the page can be correctly restored, but at a price
in increasing the amount of data that must be written to WAL.
(Because WAL replay always starts from a checkpoint, it is sufficient
to do this during the first change of each page after a checkpoint.
Therefore, one way to reduce the cost of full-page writes is to
increase the checkpoint interval parameters.)
Turning this option off speeds normal operation, but
might lead to a corrupt database after an operating system crash
or power failure. The risks are similar to turning off
fsync, though smaller. It may be safe to turn off
this option if you have hardware (such as a battery-backed disk
controller) or filesystem software (e.g., Reiser4) that reduces
the risk of partial page writes to an acceptably low level.
Turning off this option does not affect use of
WAL archiving for point-in-time recovery (PITR)
(see Section 36.3).
This option can only be set at server start or in the
postgresql.conf file. The default is
on.
- wal_buffers (integer)
Number of disk-page buffers allocated in shared memory for WAL data.
The default is 8. The setting need only be large enough to hold
the amount of WAL data generated by one typical transaction.
This option can only be set at server start.
- commit_delay (integer)
Time delay between writing a commit record to the WAL buffer
and flushing the buffer out to disk, in microseconds. A
nonzero delay can allow multiple transactions to be committed
with only one fsync() system call, if
system load is high enough that additional transactions become
ready to commit within the given interval. But the delay is
just wasted if no other transactions become ready to
commit. Therefore, the delay is only performed if at least
commit_siblings other transactions are
active at the instant that a server process has written its
commit record. The default is zero (no delay).
- commit_siblings (integer)
Minimum number of concurrent open transactions to require
before performing the commit_delay delay. A larger
value makes it more probable that at least one other
transaction will become ready to commit during the delay
interval. The default is five.
- checkpoint_segments (integer)
Maximum distance between automatic WAL checkpoints, in log
file segments (each segment is normally 16 megabytes). The
default is three. This option can only be set at server start
or in the postgresql.conf file.
- checkpoint_timeout (integer)
Maximum time between automatic WAL checkpoints, in
seconds. The default is 300 seconds. This option can only be
set at server start or in the postgresql.conf
file.
- checkpoint_warning (integer)
Write a message to the server logs if checkpoints caused by
the filling of checkpoint segment files happen closer together
than this many seconds. The default is 30 seconds.
Zero turns off the warning.
- archive_command (string)
The shell command to execute to archive a completed segment of
the WAL file series. If this is an empty string (the default),
WAL archiving is disabled. Any %p in the string is
replaced by the absolute path of the file to archive, and any
%f is replaced by the file name only. Use
%% to embed an actual % character in the
command. For more information see Section 36.3.1. This option can only be set at
server start or in the postgresql.conf
file.
It is important for the command to return a zero exit status only if
it succeeds. Examples:
archive_command = 'cp "%p" /mnt/server/archivedir/"%f"'
archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Windows
These configuration parameters provide a crude method for
influencing the query plans chosen by the query optimizer. If
the default plan chosen by the optimizer for a particular query
is not optimal, a temporary solution may be found by using one
of these configuration parameters to force the optimizer to
choose a better plan. Other ways to improve the quality of the
plans chosen by the optimizer include configuring the Planner Cost Constants, running ANALYZE more
frequently, increasing the value of the default_statistics_target configuration parameter,
and increasing the amount of statistics collected for a
particular column using ALTER TABLE SET
STATISTICS.
- enable_bitmapscan (boolean)
Enables or disables the query planner's use of bitmap-scan plan
types. The default is on.
- enable_hashagg (boolean)
Enables or disables the query planner's use of hashed
aggregation plan types. The default is on. This is used for
debugging the query planner.
- enable_hashjoin (boolean)
Enables or disables the query planner's use of hash-join plan
types. The default is on. This is used for debugging the query
planner.
- enable_indexscan (boolean)
Enables or disables the query planner's use of index-scan plan
types. The default is on. This is used for debugging the query
planner.
- enable_mergejoin (boolean)
Enables or disables the query planner's use of merge-join plan
types. The default is on. This is used for debugging the query
planner.
- enable_nestloop (boolean)
Enables or disables the query planner's use of nested-loop join
plans. It's not possible to suppress nested-loop joins entirely,
but turning this variable off discourages the planner from using
one if there are other methods available. The default is
on. This is used for debugging the query planner.
- enable_seqscan (boolean)
Enables or disables the query planner's use of sequential scan
plan types. It's not possible to suppress sequential scans
entirely, but turning this variable off discourages the planner
from using one if there are other methods available. The
default is on. This is used for debugging the query planner.
- enable_sort (boolean)
Enables or disables the query planner's use of explicit sort
steps. It's not possible to suppress explicit sorts entirely,
but turning this variable off discourages the planner from
using one if there are other methods available. The default
is on. This is used for debugging the query planner.
- enable_tidscan (boolean)
Enables or disables the query planner's use of TID
scan plan types. The default is on. This is used for debugging
the query planner.
Note: Unfortunately, there is no well-defined method for determining
ideal values for the family of "cost" variables that
appear below. You are encouraged to experiment and share
your findings.
- effective_cache_size (floating point)
Sets the planner's assumption about the effective size of the
disk cache that is available to a single index scan. This is
factored into estimates of the cost of using an index; a higher
value makes it more likely index scans will be used, a lower
value makes it more likely sequential scans will be used. When
setting this parameter you should consider both
EnterpriseDB's shared buffers and the
portion of the kernel's disk cache that will be used for
EnterpriseDB data files. Also, take into
account the expected number of concurrent queries using different
indexes, since they will have to share the available space.
This parameter has no effect on the size of shared memory
allocated by EnterpriseDB, nor does it reserve kernel disk cache;
it is used only for estimation purposes.
The value is measured in disk pages, which are
normally 8192 bytes each. The default is 1000.
- random_page_cost (floating point)
Sets the planner's estimate of the cost of a
nonsequentially fetched disk page. This is measured as a
multiple of the cost of a sequential page fetch. A higher
value makes it more likely a sequential scan will be used, a
lower value makes it more likely an index scan will be
used. The default is four.
- cpu_tuple_cost (floating point)
Sets the planner's estimate of the cost of processing
each row during a query. This is measured as a fraction of
the cost of a sequential page fetch. The default is 0.01.
- cpu_index_tuple_cost (floating point)
Sets the planner's estimate of the cost of processing
each index row during an index scan. This is measured as a
fraction of the cost of a sequential page fetch. The default
is 0.001.
- cpu_operator_cost (floating point)
Sets the planner's estimate of the cost of processing each
operator in a WHERE clause. This is measured as a fraction of
the cost of a sequential page fetch. The default is 0.0025.
- geqo (boolean)
Enables or disables genetic query optimization, which is an
algorithm that attempts to do query planning without
exhaustive searching. This is on by default. The
geqo_threshold variable provides a more
granular way to disable GEQO for certain classes of queries.
- geqo_threshold (integer)
Use genetic query optimization to plan queries with at least
this many FROM items involved. (Note that an outer
JOIN construct counts as only one FROM
item.) The default is 12. For simpler queries it is usually best
to use the deterministic, exhaustive planner, but for queries with
many tables the deterministic planner takes too long.
- geqo_effort
(integer)
Controls the tradeoff between planning time and query plan
efficiency in GEQO. This variable must be an integer in the
range from 1 to 10. The default value is 5. Larger values
increase the time spent doing query planning, but also
increase the likelyhood that an efficient query plan will be
chosen.
geqo_effort doesn't actually do anything
directly; it is only used to compute the default values for
the other variables that influence GEQO behavior (described
below). If you prefer, you can set the other parameters by
hand instead.
- geqo_pool_size (integer)
Controls the pool size used by GEQO. The pool size is the
number of individuals in the genetic population. It must be
at least two, and useful values are typically 100 to 1000. If
it is set to zero (the default setting) then a suitable
default is chosen based on geqo_effort and
the number of tables in the query.
- geqo_generations (integer)
Controls the number of generations used by GEQO. Generations
specifies the number of iterations of the algorithm. It must
be at least one, and useful values are in the same range as
the pool size. If it is set to zero (the default setting)
then a suitable default is chosen based on
geqo_pool_size.
- geqo_selection_bias (floating point)
Controls the selection bias used by GEQO. The selection bias
is the selective pressure within the population. Values can be
from 1.50 to 2.00; the latter is the default.
- default_statistics_target (integer)
Sets the default statistics target for table columns that have
not had a column-specific target set via ALTER TABLE
SET STATISTICS. Larger values increase the time needed to
do ANALYZE, but may improve the quality of the
planner's estimates. The default is 10. For more information
on the use of statistics by the EnterpriseDB
query planner, refer to Section 13.3.
- constraint_exclusion (boolean)
Enables or disables the query planner's use of table constraints to
optimize queries. The default is off.
When this parameter is on, the planner compares
query conditions with table CHECK constraints, and
omits scanning tables for which the conditions contradict the
constraints. (Presently this is done only for child tables of
inheritance scans.) For example:
CREATE TABLE parent(key integer, ...);
CREATE TABLE child1000(check (key between 1000 and 1999)) INHERITS(parent);
CREATE TABLE child2000(check (key between 2000 and 2999)) INHERITS(parent);
...
SELECT * FROM parent WHERE key = 2400;
With constraint exclusion enabled, this SELECT
will not scan child1000 at all. This can
improve performance when inheritance is used to build
partitioned tables.
Currently, constraint_exclusion is disabled by
default because it risks incorrect results if query plans are
cached - if a table constraint is changed or dropped,
the previously generated plan might now be wrong, and there is
no built-in mechanism to force re-planning. (This deficiency
will probably be addressed in a future
EnterpriseDB release.) Another reason for
keeping it off is that the constraint checks are relatively
expensive, and in many circumstances will yield no savings.
It is recommended to turn this on only if you are actually
using partitioned tables designed to take advantage of the
feature.
Refer to partitioning for more information
on using constraint exclusion and partitioning.
- from_collapse_limit (integer)
The planner will merge sub-queries into upper queries if the
resulting FROM list would have no more than
this many items. Smaller values reduce planning time but may
yield inferior query plans. The default is 8. It is usually
wise to keep this less than geqo_threshold.
- join_collapse_limit (integer)
The planner will rewrite explicit inner JOIN
constructs into lists of FROM items whenever a
list of no more than this many items in total would
result.
The query planner reorders inner joins written in this manner, hence
significantly improving performance, and this configuration parameter controls
the extent to which this reordering is performed.
Note: At present, the order of outer joins specified via the
JOIN construct is never adjusted by the query
planner; therefore, join_collapse_limit has no
effect on this behavior. The planner may be improved to
reorder some classes of outer joins in a future release of
EnterpriseDB.
By default, this variable is set the same as
from_collapse_limit, which is appropriate
for most uses. Setting it to 1 prevents any reordering of
inner JOINs. Thus, the explicit join order
specified in the query will be the actual order in which the
relations are joined. The query planner does not always choose
the optimal join order; advanced users may elect to
temporarily set this variable to 1, and then specify the join
order they desire explicitly.
Setting this variable to a value between 1 and
from_collapse_limit might be useful to
trade off planning time against the quality of the chosen plan
(higher values produce better plans).
- log_destination (string)
EnterpriseDB supports several methods
for logging server messages, including
stderr and
syslog. On Windows,
eventlog is also supported. Set this
option to a list of desired log destinations separated by
commas. The default is to log to stderr
only.
This option can only be set at server start or in the
postgresql.conf configuration file.
- redirect_stderr (boolean)
This option allows messages sent to stderr to be
captured and redirected into log files.
This option, in combination with logging to stderr,
is often more useful than
logging to syslog, since some types of messages
may not appear in syslog output (a common example
is dynamic-linker failure messages).
This option can only be set at server start.
- log_directory (string)
When redirect_stderr is enabled, this option
determines the directory in which log files will be created.
It may be specified as an absolute path, or relative to the
cluster data directory.
This option can only be set at server start or in the
postgresql.conf configuration file.
- log_filename (string)
When redirect_stderr is enabled, this option
sets the file names of the created log files. The value
is treated as a strftime pattern,
so %-escapes
can be used to specify time-varying file names.
If no %-escapes are present,
EnterpriseDB will
append the epoch of the new log file's open time. For example,
if log_filename were server_log, then the
chosen file name would be server_log.1093827753
for a log starting at Sun Aug 29 19:02:33 2004 MST.
This option can only be set at server start or in the
postgresql.conf configuration file.
- log_rotation_age (integer)
When redirect_stderr is enabled, this option
determines the maximum lifetime of an individual log file.
After this many minutes have elapsed, a new log file will
be created. Set to zero to disable time-based creation of
new log files.
This option can only be set at server start or in the
postgresql.conf configuration file.
- log_rotation_size (integer)
When redirect_stderr is enabled, this option
determines the maximum size of an individual log file.
After this many kilobytes have been emitted into a log file,
a new log file will be created. Set to zero to disable size-based
creation of new log files.
This option can only be set at server start or in the
postgresql.conf configuration file.
- log_truncate_on_rotation (boolean)
When redirect_stderr is enabled, this option will cause
EnterpriseDB to truncate (overwrite),
rather than append to, any existing log file of the same name.
However, truncation will occur only when a new file is being opened
due to time-based rotation, not during server startup or size-based
rotation. When false, pre-existing files will be appended to in
all cases. For example, using this option in combination with
a log_filename like postgresql-%H.log
would result in generating twenty-four hourly log files and then
cyclically overwriting them.
This option can only be set at server start or in the
postgresql.conf configuration file.
Example: To keep 7 days of logs, one log file per day named
server_log.Mon, server_log.Tue,
etc, and automatically overwrite last week's log with this week's log,
set log_filename to server_log.%a,
log_truncate_on_rotation to true, and
log_rotation_age to 1440.
Example: To keep 24 hours of logs, one log file per hour, but
also rotate sooner if the log file size exceeds 1GB, set
log_filename to server_log.%H%M,
log_truncate_on_rotation to true,
log_rotation_age to 60, and
log_rotation_size to 1000000.
Including %M in log_filename allows
any size-driven rotations that may occur to select a filename
different from the hour's initial filename.
- syslog_facility (string)
When logging to syslog is enabled, this option
determines the syslog
"facility" to be used. You may choose
from LOCAL0, LOCAL1,
LOCAL2, LOCAL3, LOCAL4,
LOCAL5, LOCAL6, LOCAL7;
the default is LOCAL0. See also the
documentation of your system's
syslog daemon.
This option can only be set at server start.
- syslog_ident (string)
When logging to syslog is enabled, this option
determines the program name used to identify
EnterpriseDB messages in
syslog logs. The default is
enterprisedb.
This option can only be set at server start.
- client_min_messages (string)
Controls which message levels are sent to the client.
Valid values are DEBUG5,
DEBUG4, DEBUG3, DEBUG2,
DEBUG1, LOG, NOTICE,
WARNING, and ERROR. Each level
includes all the levels that follow it. The later the level,
the fewer messages are sent. The default is
NOTICE. Note that LOG has a different
rank here than in log_min_messages.
- log_min_messages (string)
Controls which message levels are written to the server log.
Valid values are DEBUG5, DEBUG4,
DEBUG3, DEBUG2, DEBUG1,
INFO, NOTICE, WARNING,
ERROR, LOG, FATAL, and
PANIC. Each level includes all the levels that
follow it. The later the level, the fewer messages are sent
to the log. The default is NOTICE. Note that
LOG has a different rank here than in
client_min_messages.
Only superusers can change this setting.
- log_error_verbosity (string)
Controls the amount of detail written in the server log for each
message that is logged. Valid values are TERSE,
DEFAULT, and VERBOSE, each adding more
fields to displayed messages.
- log_min_error_statement (string)
Controls whether or not the SQL statement that causes an error
condition will also be recorded in the server log. All SQL
statements that cause an error of the specified level or
higher are logged. The default is
PANIC (effectively turning this feature
off for normal use). Valid values are DEBUG5,
DEBUG4, DEBUG3,
DEBUG2, DEBUG1,
INFO, NOTICE,
WARNING, ERROR,
FATAL, and PANIC. For
example, if you set this to ERROR then all
SQL statements causing errors, fatal errors, or panics will be
logged. Enabling this option can be helpful in tracking down
the source of any errors that appear in the server log.
Only superusers can change this setting.
- log_min_duration_statement (integer)
Sets a minimum statement execution time (in milliseconds)
that causes a statement to be logged. All SQL statements
that run for the time specified or longer will be logged with
their duration. Setting this to zero will print
all queries and their durations. Minus-one (the default)
disables the feature. For example, if you set it to
250 then all SQL statements that run 250ms
or longer will be logged. Enabling this option can be
useful in tracking down unoptimized queries in your applications.
Only superusers can change this setting.
- silent_mode (boolean)
Runs the server silently. If this option is set, the server
will automatically run in background and any controlling
terminals are disassociated (same effect as
edb-postmaster's -S option).
The server's standard output and standard error are redirected
to /dev/null, so any messages sent to them will be lost.
Unless syslog logging is selected or
redirect_stderr is enabled, using this option
is discouraged because it makes it impossible to see error messages.
Here is a list of the various message severity levels used in
these settings:
- DEBUG[1-5]
Provides information for use by developers.
- INFO
Provides information implicitly requested by the user,
e.g., during VACUUM VERBOSE.
- NOTICE
Provides information that may be helpful to users, e.g.,
truncation of long identifiers and the creation of indexes as part
of primary keys.
- WARNING
Provides warnings to the user, e.g., COMMIT
outside a transaction block.
- ERROR
Reports an error that caused the current transaction to abort.
- LOG
Reports information of interest to administrators, e.g.,
checkpoint activity.
- FATAL
Reports an error that caused the current session to abort.
- PANIC
Reports an error that caused all sessions to abort.
- debug_print_parse (boolean)
debug_print_rewritten (boolean) debug_print_plan (boolean) debug_pretty_print (boolean) These options enable various debugging output to be sent to
the client or server log. For each executed query, they print
the resulting parse tree, the query rewriter output, or the
execution plan. debug_pretty_print indents
these displays to produce a more readable but much longer
output format. client_min_messages or
log_min_messages must be
DEBUG1 or lower to send the output to the
client or server logs. These options are off by default.
- log_connections (boolean)
This outputs a line to the server logs detailing each successful
connection. This is off by default, although it is probably very
useful. This option can only be set at server start or in the
postgresql.conf configuration file.
- log_disconnections (boolean)
This outputs a line in the server logs similar to
log_connections but at session termination,
and includes the duration of the session. This is off by
default. This option can only be set at server start or in the
postgresql.conf configuration file.
- log_duration (boolean)
Causes the duration of every completed statement which satisfies
log_statement to be logged. When using this option,
if you are not using syslog, it is recommended
that you log the PID or session ID using log_line_prefix
so that you can link the statement to the
duration using the process ID or session ID. The default is off.
Only superusers can change this setting.
- log_line_prefix (string)
This is a printf -style string that is output at the
beginning of each log line. The default is an empty string.
Each recognized escape is replaced as outlined
below - anything else that looks like an escape is ignored. Other
characters are copied straight to the log line. Some escapes are
only recognised by session processes, and do not apply to
background processes such as the edb-postmaster. Syslog
produces its own
timestamp and process ID information, so you probably do not want to
use those escapes if you are using syslog.
This option can only be set at server start or in the
postgresql.conf configuration file.
- log_statement (string)
Controls which SQL statements are logged. Valid values are
none, ddl, mod, and
all. ddl logs all data definition
commands like CREATE, ALTER, and
DROP commands. mod logs all
ddl statements, plus INSERT,
UPDATE, DELETE, TRUNCATE,
and COPY FROM. PREPARE and
EXPLAIN ANALYZE statements are also logged if their
contained command is of an appropriate type.
The default is none. Only superusers can change this
setting.
Note: The EXECUTE statement is not considered a
ddl or mod statement. When it is logged,
only the name of the prepared statement is reported, not the
actual prepared statement.
When a function is defined in the
SPLserver-side language, any queries
executed by the function will only be logged the first time that the
function is invoked in a particular session. This is because
SPL keeps a cache of the
query plans produced for the SQL statements in the function.
- log_hostname (boolean)
By default, connection logs only show the IP address of the
connecting host. If you want it to show the host name you can
turn this on, but depending on your host name resolution setup
it might impose a non-negligible performance penalty. This
option can only be set at server start.
EnterpriseDB database auditing allows database and system administrators, security administrators, auditors
and operators to track and analyze database activities. These activities include database access and usage along with data
creation, change or deletion.
The auditing system is based on the configuration parameters defined in the postgresql.conf file. The following
is the syntax and the possible values of the database auditing parameters.
- edb_audit
Enables or disables database auditing. The values xml or
csv will enable database auditing. These values represent the file format in
which auditing information will be captured. none will disable database auditing and is also
the default value. This option can only be set at server start or in the postgresql.conf.
- edb_audit_directory
Specifies the directory where the log files will be created. The path of the directory can be relative or absolute
to the data folder. This option can only be set at server start or in the postgresql.conf configuration file.
- edb_audit_filename
Specifies the file name of the audit file where the auditing information will be stored. The default file name will be
'audit-%Y-%m-%d_%H%M%S'. The escape sequences, %Y, %m etc., will be replaced by the appropriate current
values according to system date and time. This option can only be set at server start or in the
postgresql.conf configuration file.
- edb_audit_rotation_day
Specifies the day of the week on which to rotate the audit files. Valid values are sun,
mon, tue, wed, thu,
fri, sat, every and none.
To disable rotation, set the value none. To rotate the file every day, set the
edb_audit_rotation_day value to every. To rotate the file on a specific day of a
week, set the value of any day of the week. none is the default value. This option can only be set
at server start or in the postgresql.conf configuration file.
- edb_audit_rotation_size
Specifies a file size threshold in megabytes when file rotation will be forced to occur. The default value is
0 MB. If the parameter is commented out or set to 0, rotation of the file on size basis will not
occur. This option can only be set at server start or in the postgresql.conf configuration file.
- edb_audit_rotation_seconds
Specifies the rotation time in seconds when a new log file should be created. To disable this feature, set this parameter
to 0. This option can only be set at server start or in the postgresql.conf configuration file.
- edb_audit_connect
Enables auditing of database connection attempts by users. To disable auditing of all connection attempts, set
edb_audit_connect set to none. To audit all failed connection attempts, set the
value to failed. To audit all connection attempts, set the value to all.
This option can only be set at server start or in the postgresql.conf configuration file.
- edb_audit_disconnect
Enables auditing of database disconnections by connected users. To enable auditing of disconnections, set the value
to all. To disable, set the value to none. This option can only be set
at server start or in the postgresql.conf configuration file.
- edb_audit_statement
This configuration parameter is used to specify auditing of different categories of SQL statements.
To audit statements resulting in error, set the parameter value to error. To audit DDL
statements such as CREATE TABLE, ALTER TABLE, etc., set the parameter value to ddl.
Modification statements such as INSERT, UPDATE, DELETE etc., can be audited by setting
edb_audit_statement to dml. Setting the value to all
will audit every statement while none disables this feature. This option can only be set at server
start or in the postgresql.conf configuration file.
Suppose we need to audit all connections, disconnections, DDL statements and statements resulting in an error.
The audit file is to be rotated every Sunday.
Enable auditing by the setting the edb_audit parameter to xml or
csv. Set the file rotation day when the new file will be created by setting the parameter edb_audit_rotation_day
to sun. To audit all connections, set the parameter, edb_audit_connect, to all. To audit all disconnections, set the parameter, edb_audit_disconnect, to all. To audit all DDL statements and error statements, set the parameter, edb_audit_statement,
to dll, error.
Each audit line is preceded with a fixed prefix that cannot be changed. The prefix consists of user name, database name,
remote host and port, process id, session id, transaction id, timestamp, and event type.
The following is the CVS and XML output when auditing is enabled: CSV output:
,,,17544,,,2006-05-12 18:27:37 PKT ,startup,"AUDIT: database system is ready"
edb,edb,[local],17551,44648d4d.448f,0,2006-05-12 18:27:41 PKT ,connect,"AUDIT: connection authorized: user=edb database=edb"
edb,edb,[local],17551,44648d4d.448f,661,2006-05-12 18:27:43 PKT ,ddl,"AUDIT: statement: create table testing(a integer);"
edb,edb,[local],17551,44648d4d.448f,663,2006-05-12 18:27:46 PKT ,ddl,"AUDIT: statement: drop table testing;"
edb,edb,[local],17551,44648d4d.448f,0,2006-05-12 18:27:47 PKT ,disconnect,"AUDIT: disconnection: session time: 0:00:06.43
user=edb database=edb host=[local]"
,,,17545,,,2006-05-12 18:27:50 PKT ,shutdown,"AUDIT: database system is shut down"
XML output:
<?xml version="1.0" encoding="ISO-8859-1"?>
<EnterpriseDBAuditReports>
<event process_id="16863" time="2006-05-12 18:14:23 PKT " type="startup">
<message>AUDIT: database system is ready</message>
</event>
<event user="edb" database="edb" remote_host_and_port="[local]" process_id="16906" session_id="44648a46.420a"
transaction="0" time="2006-05-12 18:14:46 PKT " type="connect">
<message>AUDIT: connection authorized: user=edb database=edb</message>
</event>
<event user="edb" database="edb" remote_host_and_port="[local]" process_id="16906" session_id="44648a46.420a"
transaction="655" time="2006-05-12 18:14:55 PKT " type="ddl">
<command>AUDIT: statement: create table testing(a integer);</command>
</event>
<event user="edb" database="edb" remote_host_and_port="[local]" process_id="16906" session_id="44648a46.420a"
transaction="657" time="2006-05-12 18:15:11 PKT " type="ddl">
<command>AUDIT: statement: drop table testing;</command>
</event>
<event user="edb" database="edb" remote_host_and_port="[local]" process_id="16906" session_id="44648a46.420a"
transaction="0" time="2006-05-12 18:15:13 PKT " type="disconnect">
<message>AUDIT: disconnection: session time: 0:00:27.13 user=edb database=edb host=[local]</message>
</event>
<event process_id="16864" time="2006-05-12 18:15:18 PKT " type="shutdown">
<message>AUDIT: database system is shut down</message>
</event>
</EnterpriseDBAuditReports>
- log_statement_stats (boolean)
log_parser_stats (boolean) log_planner_stats (boolean) log_executor_stats (boolean) For each query, write performance statistics of the respective
module to the server log. This is a crude profiling
instrument. log_statement_stats reports total
statement statistics, while the others report per-module statistics.
log_statement_stats cannot be enabled together with
any of the per-module options. All of these options are disabled by
default. Only superusers can change these settings.
- stats_start_collector (boolean)
Controls whether the server should start the
statistics-collection subprocess. This is on by default, but
may be turned off if you know you have no interest in
collecting statistics. This option can only be set at server
start.
- stats_command_string (boolean)
Enables the collection of statistics on the currently
executing command of each session, along with the time at
which that command began execution. This option is off by
default. Note that even when enabled, this information is not
visible to all users, only to superusers and the user owning
the session being reported on; so it should not represent a
security risk. This data can be accessed via the
pg_stat_activity system view; refer
to Chapter 37 for more information.
- stats_block_level (boolean)
Enables the collection of block-level statistics on database
activity. This option is disabled by default. If this option
is enabled, the data that is produced can be accessed via the
pg_stat and
pg_statio family of system views;
refer to Chapter 37 for more information.
- stats_row_level (boolean)
Enables the collection of row-level statistics on database
activity. This option is disabled by default. If this option
is enabled, the data that is produced can be accessed via the
pg_stat and
pg_statio family of system views;
refer to Chapter 37 for more information.
- stats_reset_on_server_start (boolean)
If on, collected statistics are zeroed out whenever the server
is restarted. If off, statistics are accumulated across server
restarts. The default is on. This option can only be set at
server start.
These settings control the default behavior for the autovacuum
daemon.
- autovacuum (boolean)
Controls whether the server should start the
autovacuum subprocess. This is off by default.
stats_start_collector and stats_row_level
must also be on for this to start.
This option can only be set at server start or in the
postgresql.conf file.
- autovacuum_naptime (integer)
Specifies the delay between activity rounds for the autovacuum
subprocess. In each round the subprocess examines one database
and issues VACUUM and ANALYZE commands
as needed for tables in that database. The delay is measured
in seconds, and the default is 60.
This option can only be set at server start or in the
postgresql.conf file.
- autovacuum_vacuum_threshold (integer)
Specifies the minimum number of updated or deleted tuples needed
to trigger a VACUUM in any one table.
The default is 1000.
This option can only be set at server start or in the
postgresql.conf file.
This setting can be overridden for individual tables by entries in
pg_autovacuum.
- autovacuum_analyze_threshold (integer)
Specifies the minimum number of inserted, updated or deleted tuples
needed to trigger an ANALYZE in any one table.
The default is 500.
This option can only be set at server start or in the
postgresql.conf file.
This setting can be overridden for individual tables by entries in
pg_autovacuum.
- autovacuum_vacuum_scale_factor (floating point)
Specifies a fraction of the table size to add to
autovacuum_vacuum_threshold
when deciding whether to trigger a VACUUM.
The default is 0.4.
This option can only be set at server start or in the
postgresql.conf file.
This setting can be overridden for individual tables by entries in
pg_autovacuum.
- autovacuum_analyze_scale_factor (floating point)
Specifies a fraction of the table size to add to
autovacuum_analyze_threshold
when deciding whether to trigger an ANALYZE.
The default is 0.2.
This option can only be set at server start or in the
postgresql.conf file.
This setting can be overridden for individual tables by entries in
pg_autovacuum.
- autovacuum_vacuum_cost_delay (integer)
Specifies the cost delay value that will be used in automatic
VACUUM operations. If -1 is specified (which is the
default), the regular
vacuum_cost_delay value will be used.
This setting can be overridden for individual tables by entries in
pg_autovacuum.
- autovacuum_vacuum_cost_limit (integer)
Specifies the cost limit value that will be used in automatic
VACUUM operations. If -1 is specified (which is the
default), the regular
vacuum_cost_limit value will be used.
This setting can be overridden for individual tables by entries in
pg_autovacuum.
- search_path (string)
This variable specifies the order in which schemas are searched
when an object (table, data type, function, etc.) is referenced by a
simple name with no schema component. When there are objects of
identical names in different schemas, the one found first
in the search path is used. An object that is not in any of the
schemas in the search path can only be referenced by specifying
its containing schema with a qualified (dotted) name.
The value for search_path has to be a comma-separated
list of schema names. If one of the list items is
the special value $user, then the schema
having the name returned by SESSION_USER is substituted, if there
is such a schema. (If not, $user is ignored.)
The system catalog schema, pg_catalog, is always
searched, whether it is mentioned in the path or not. If it is
mentioned in the path then it will be searched in the specified
order. If pg_catalog is not in the path then it will
be searched before searching any of the path items.
It should also be noted that the temporary-table schema,
pg_temp_nnn, is implicitly searched before any of
these.
When objects are created without specifying a particular target
schema, they will be placed in the first schema listed
in the search path. An error is reported if the search path is
empty.
The default value for this parameter is
'$user, public' (where the second part will be
ignored if there is no schema named public).
This supports shared use of a database (where no users
have private schemas, and all share use of public),
private per-user schemas, and combinations of these. Other
effects can be obtained by altering the default search path
setting, either globally or per-user.
The current effective value of the search path can be examined
via the SQL function
current_schemas() . This is not quite the same as
examining the value of search_path, since
current_schemas() shows how the requests
appearing in search_path were resolved.
For more information on schema handling, see Section 4.7.
- default_tablespace (string)
This variable specifies the default tablespace in which to create
objects (tables and indexes) when a CREATE command does
not explicitly specify a tablespace.
The value is either the name of a tablespace, or an empty string
to specify using the default tablespace of the current database.
If the value does not match the name of any existing tablespace,
EnterpriseDB will automatically use the default
tablespace of the current database.
For more information on tablespaces,
see Section 32.6.
- check_function_bodies (boolean)
This parameter is normally true. When set to false, it disables
validation of the function body string in CREATE FUNCTION. Disabling validation is
occasionally useful to avoid problems such as forward
references when restoring function definitions from a dump.
- default_transaction_isolation (string)
Each SQL transaction has an isolation level, which can be
either "read uncommitted", "read
committed", "repeatable read", or
"serializable". This parameter controls the
default isolation level of each new transaction. The default
is "read committed".
Consult MVCC and SET TRANSACTION for more
information.
- default_transaction_read_only (boolean)
A read-only SQL transaction cannot alter non-temporary tables.
This parameter controls the default read-only status of each new
transaction. The default is false (read/write).
Consult SET TRANSACTION for more information.
- statement_timeout (integer)
Aborts any statement that takes over the specified number of
milliseconds. A value of zero (the default) turns off the limitation.
- DateStyle (string)
Sets the display format for date and time values, as well as the
rules for interpreting ambiguous date input values. For historical reasons,
this variable contains two independent components:
the output format specification (Redwood, ISO, SQL, or German) and the
input/output specification for year/month/day ordering (DMY, MDY, or YMD)
for all the DateStyles except for Redwood which does not have an ordering
component, but instead takes a parameter (hide_time, show_time) to either
suppress or show the time component of a TIMESTAMP(0) value upon display.
The default DateStyle is set to "redwood,show_time".
These can be set separately or together. The keywords Euro
and European are synonyms for DMY; the
keywords US, NonEuro, and
NonEuropean are synonyms for MDY. See
Section 7.4 for more information.
- edb_redwood_date (boolean)
Sets whether or not a column with the DATE data type also
stores a time component when a table is created or the column is altered.
If set to true, the DATE data type in a CREATE TABLE
or ALTER TABLE command is translated to TIMESTAMP(0)
when the table is defined or the column is altered.
If set to false, the DATE data type in a CREATE
TABLE or ALTER TABLE command remains as the DATE
data type.
Note that this configuration parameter has no effect on the
DATE data type when used in any other context such as the data
type of a variable in an SPL declaration section, or the
data type of a formal parameter in an SPL procedure or
an SPL function, or the return type of an
SPL function. In these
cases DATE is always translated to TIMESTAMP(0). See Section 7.4 for more information.
- timezone (string)
Sets the time zone for displaying and interpreting time
stamps. The default is to use whatever the system environment
specifies as the time zone. See Section 7.4 for more information.
- australian_timezones (boolean)
If set to true, ACST,
CST, EST, and
SAT are interpreted as Australian time
zones rather than as North/South American time zones and
Saturday. The default is false.
- extra_float_digits (integer)
This parameter adjusts the number of digits displayed for
floating-point values, including float4, float8,
and geometric data types. The parameter value is added to the
standard number of digits (FLT_DIG or DBL_DIG
as appropriate). The value can be set as high as 2, to include
partially-significant digits; this is especially useful for dumping
float data that needs to be restored exactly. Or it can be set
negative to suppress unwanted digits.
- client_encoding (string)
Sets the client-side encoding (character set).
The default is to use the database encoding.
- lc_messages (string)
Sets the language in which messages are displayed. Acceptable
values are system-dependent; see Section 34.1 for
more information. If this variable is set to the empty string
(which is the default) then the value is inherited from the
execution environment of the server in a system-dependent way.
On some systems, this locale category does not exist. Setting
this variable will still work, but there will be no effect.
Also, there is a chance that no translated messages for the
desired language exist. In that case you will continue to see
the English messages.
- lc_monetary (string)
Sets the locale to use for formatting monetary amounts, for
example with the to_char family of
functions. Acceptable values are system-dependent; see Section 34.1 for more information. If this variable is
set to the empty string (which is the default) then the value
is inherited from the execution environment of the server in a
system-dependent way.
- lc_numeric (string)
Sets the locale to use for formatting numbers, for example
with the to_char family of
functions. Acceptable values are system-dependent; see Section 34.1 for more information. If this variable is
set to the empty string (which is the default) then the value
is inherited from the execution environment of the server in a
system-dependent way.
- lc_time (string)
Sets the locale to use for formatting date and time values.
(Currently, this setting does nothing, but it may in the
future.) Acceptable values are system-dependent; see Section 34.1 for more information. If this variable is
set to the empty string (which is the default) then the value
is inherited from the execution environment of the server in a
system-dependent way.
- explain_pretty_print (boolean)
Determines whether EXPLAIN VERBOSE uses the
indented or non-indented format for displaying detailed
query-tree dumps. The default is on.
- dynamic_library_path (string)
If a dynamically loadable module needs to be opened and the
file name specified in the CREATE FUNCTION or
LOAD command
does not have a directory component (i.e. the
name does not contain a slash), the system will search this
path for the required file.
The value for dynamic_library_path has to be a
list of absolute directory paths separated by colons (or semi-colons
on Windows). If a list element starts
with the special string $libdir, the
compiled-in EnterpriseDB package
library directory is substituted for $libdir. This
is where the modules provided by the standard
EnterpriseDB distribution are installed.
(Use pg_config --pkglibdir to find out the name of
this directory.) For example:
dynamic_library_path = '/usr/local/lib/enterprisedb:/home/my_project/lib:$libdir'
or, in a Windows environment:
dynamic_library_path = 'C:\tools\enterprisedb;H:\my_project\lib;$libdir'
The default value for this parameter is
'$libdir'. If the value is set to an empty
string, the automatic path search is turned off.
This parameter can be changed at run time by superusers, but a
setting done that way will only persist until the end of the
client connection, so this method should be reserved for
development purposes. The recommended way to set this parameter
is in the postgresql.conf configuration
file.
- escape_string_warning (boolean)
When on, a warning is issued if a backslash (\)
appears in an ordinary string literal ('...'
syntax). The default is off.
Escape string syntax (E'...') should be used for
escapes, because in future versions of
EnterpriseDB ordinary strings will have
the standard-conforming behavior of treating backslashes
literally.
- custom_variable_classes (string)
This variable specifies one or several class names to be used for
custom variables, in the form of a comma-separated list. A custom
variable is a variable not normally known
to EnterpriseDB proper but used by some
add-on module. Such variables must have names consisting of a class
name, a dot, and a variable name. custom_variable_classes
specifies all the class names in use in a particular installation.
This option can only be set at server start or in the
postgresql.conf configuration file.
The difficulty with setting custom variables in
postgresql.conf is that the file must be read before add-on
modules have been loaded, and so custom variables would ordinarily be
rejected as unknown. When custom_variable_classes is set,
the server will accept definitions of arbitrary variables within each
specified class. These variables will be treated as placeholders and
will have no function until the module that defines them is loaded. When a
module for a specific class is loaded, it will add the proper variable
definitions for its class name, convert any placeholder
values according to those definitions, and issue warnings for any
placeholders of its class that remain (which presumably would be
misspelled configuration variables).
Here is an example of what postgresql.conf might contain
when using custom variables:
custom_variable_classes = 'plr,plperl'
plr.path = '/usr/lib/R'
plperl.use_strict = true
plruby.use_strict = true # generates error: unknown class name
- deadlock_timeout (integer)
This is the amount of time, in milliseconds, to wait on a lock
before checking to see if there is a deadlock condition. The
check for deadlock is relatively slow, so the server doesn't run
it every time it waits for a lock. We (optimistically?) assume
that deadlocks are not common in production applications and
just wait on the lock for a while before starting the check for a
deadlock. Increasing this value reduces the amount of time
wasted in needless deadlock checks, but slows down reporting of
real deadlock errors. The default is 1000 (i.e., one second),
which is probably about the smallest value you would want in
practice. On a heavily loaded server you might want to raise it.
Ideally the setting should exceed your typical transaction time,
so as to improve the odds that a lock will be released before
the waiter decides to check for deadlock.
- max_locks_per_transaction (integer)
The shared lock table is sized on the assumption that at most
max_locks_per_transaction *
max_connections distinct objects will need to
be locked at any one time. 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
transaction. This option can only be set at server start.
The following "parameters" are read-only, and are determined
when EnterpriseDB is compiled or when it is
installed. As such, they have been excluded from the sample
postgresql.conf file. These options determine
various aspects of EnterpriseDB behavior
that may be of interest to certain applications, particularly
administrative front-ends.
- block_size (integer)
Shows the size of a disk block. It is determined by the value
of BLCKSZ when building the server. The default
value is 8192 bytes. The meaning of some configuration
variables (such as shared_buffers) is
influenced by block_size. See Section 30.4.4 for information.
- integer_datetimes (boolean)
Shows whether EnterpriseDB was built
with support for 64-bit-integer dates and times. It is set by
configuring with --enable-integer-datetimes
when building EnterpriseDB. The
default value is off.
- lc_collate (string)
Shows the locale in which sorting of textual data is done.
See Section 34.1 for more information.
The value is determined when the database cluster is initialized.
- lc_ctype (string)
Shows the locale that determines character classifications.
See Section 34.1 for more information.
The value is determined when the database cluster is initialized.
Ordinarily this will be the same as lc_collate,
but for special applications it might be set differently.
- max_function_args (integer)
Shows the maximum number of function arguments. It is determined by
the value of FUNC_MAX_ARGS when building the server. The
default value is 32.
- max_identifier_length (integer)
Shows the maximum identifier length. It is determined as one
less than the value of NAMEDATALEN when building
the server. The default value of NAMEDATALEN is
64; therefore the default
max_identifier_length is 63.
- max_index_keys (integer)
Shows the maximum number of index keys. It is determined by
the value of INDEX_MAX_KEYS when building the server. The
default value is 32.
- server_encoding (string)
Shows the database encoding (character set).
It is determined when the database is created. Ordinarily,
clients need only be concerned with the value of client_encoding.
- server_version (string)
Shows the version number of the server. It is determined by the
value of PG_VERSION when building the server.
For convenience there are also single letter command-line option switches
available for some parameters. They are described in Table 30-1.
Table 30-1. Short option key Short option | Equivalent |
---|
-B x | shared_buffers = x | -d x | log_min_messages = DEBUGx | -F | fsync = off | -h x | listen_addresses = x | -i | listen_addresses = '*' | -k x | unix_socket_directory = x | -N x | max_connections = x | -p x | port = x | -fi, -fh,
-fm, -fn,
-fs, -ft
| enable_indexscan = off,
enable_hashjoin = off,
enable_mergejoin = off,
enable_nestloop = off,
enable_seqscan = off,
enable_tidscan = off
| -s | log_statement_stats = on | -S x
| work_mem = x | -tpa, -tpl, -te | log_parser_stats = on,
log_planner_stats = on,
log_executor_stats = on | Notes: a. For historical reasons, these options must be passed to
the individual server process via the -o
edb-postmaster option, for example,
$ edb-postmaster -o '-S 1024 -s'
or via PGOPTIONS from the client side, as
explained above.
|
| |
---|