diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml index 7e17a28d51..c43af2ec9b 100644 --- a/doc/src/sgml/runtime.sgml +++ b/doc/src/sgml/runtime.sgml @@ -1,5 +1,5 @@ @@ -18,22 +18,21 @@ $Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.106 2002/03/06 06:44:32 mo - As with any other server daemon that is connected to the world at - large, it is advisable to run PostgreSQL under a separate user - account. This user account should only own the data itself that is - being managed by the server, and should not be shared with other - daemons. (Thus, using the user nobody is a bad - idea.) It is not advisable to install the executables as owned by - this user account because that runs the risk of user-defined - functions gone astray or any other exploits compromising the - executable programs. + As with any other server daemon that is connected to outside world, + it is advisable to run PostgreSQL under a + separate user account. This user account should only own the data + that is managed by the server, and should not be shared with other + daemons. (For example, using the user nobody is a bad + idea.) It is not advisable to install executables owned by + this user because compromised systems could then modify their own + binaries. - To add a user account to your system, look for a command + To add a Unix user account to your system, look for a command useradd or adduser. The user - name postgres is often used but by no means - required. + name postgres is often used but is by no + means required. @@ -52,10 +51,10 @@ $Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.106 2002/03/06 06:44:32 mo Before you can do anything, you must initialize a database storage area on disk. We call this a database cluster. - (SQL speaks of a catalog cluster instead.) A - database cluster is a collection of databases that will be accessible - through a single instance of a running database server. After - initialization, a database cluster will contain one database named + (SQL uses the term catalog cluster instead.) A + database cluster is a collection of databases is accessible by a + single instance of a running database server. After initialization, a + database cluster will contain a database named template1. As the name suggests, this will be used as a template for subsequently created databases; it should not be used for actual work. @@ -76,9 +75,9 @@ $Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.106 2002/03/06 06:44:32 mo $ initdb -D /usr/local/pgsql/data - Note that you must execute this command while being logged into - the PostgreSQL user account, which is described in the previous - section. + Note that you must execute this command while logged into the + PostgreSQL user account, which is + described in the previous section. @@ -93,11 +92,12 @@ $Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.106 2002/03/06 06:44:32 mo initdb will attempt to create the directory you - specify if it does not already exist. It is likely that it won't - have the permission to do so (if you followed our advice and - created an unprivileged account). In that case you should create the - directory yourself (as root) and transfer ownership of it to the - PostgreSQL user account. Here is how this might work: + specify if it does not already exist. It is likely that it will not + have the permission to do so (if you followed our advice and created + an unprivileged account). In that case you should create the + directory yourself (as root) and change the owner to be the + PostgreSQL user. Here is how this might + be done: root# mkdir /usr/local/pgsql/data root# chown postgres /usr/local/pgsql/data @@ -108,36 +108,36 @@ postgres$ initdb -D /usr/local/pgsql/data initdb will refuse to run if the data directory - looks like it belongs to an already initialized installation. - + looks like it it has already been initialized. Because the data directory contains all the data stored in the - database, it is essential that it be well secured from unauthorized + database, it is essential that it be secured from unauthorized access. initdb therefore revokes access - permissions from everyone but the PostgreSQL user account. + permissions from everyone but the + PostgreSQL user. However, while the directory contents are secure, the default pg_hba.conf authentication method of - trust allows any local user to connect to the database - and even become the database superuser. If you don't trust other local - users, we recommend you use initdb's option - or to assign a - password to the database superuser. After initdb, + trust allows any local user to connect to the + database and even become the database superuser. If you don't trust + other local users, we recommend you use initdb's + or option to assign a + password to the database superuser. After initdb, modify pg_hba.conf to use md5 or - password, instead of trust, authentication - before you start the server for the first time. (Other, possibly - more convenient approaches include using ident - authentication or file system permissions to restrict connections. See - for more information.) + password instead of trust authentication + before you start the server for the first time. (Other, + approaches include using ident authentication or + file system permissions to restrict connections. See for more information. LC_COLLATE - One surprise you might encounter while running initdb is - a notice similar to this one: + One surprise you might encounter while running + initdb is a notice similar to this: WARNING: Initializing database with en_US collation order. This locale setting will prevent use of index optimization for @@ -145,16 +145,18 @@ WARNING: Initializing database with en_US collation order. such queries, you may wish to set LC_COLLATE to "C" and re-initdb. For more information see the Administrator's Guide. - This is intended to warn you that the currently selected locale - will cause indexes to be sorted in an order that prevents them from - being used for LIKE and regular-expression searches. If you need - good performance of such searches, you should set your current locale - to C and re-run initdb. On most systems, setting the - current locale is done by changing the value of the environment variable - LC_ALL or LANG. The sort order used - within a particular database cluster is set by initdb - and cannot be changed later, short of dumping all data, rerunning initdb, - and reloading the data. So it's important to make this choice correctly now. + This is intended to warn you that the currently selected locale will + cause indexes to be sorted in an order that prevents them from being + used for LIKE and regular-expression searches. If you need good + performance in such searches, you should set your current locale to + C and re-run initdb. On most systems, + setting the current locale is done by changing the value of the + environment variable LC_ALL or + LANG. The sort order used within a particular + database cluster is set by initdb and cannot be + changed later, short of dumping all data, rerunning + initdb, and reloading the data. So it's important + to make this choice correctly the first time. @@ -165,20 +167,20 @@ WARNING: Initializing database with en_US collation order. postmaster - Before anyone can access the database you must start the database + Before anyone can access the database, you must start the database server. The database server is called - postmaster. - The postmaster must know where to find the data it is supposed - to work on. This is done with the option. Thus, - the simplest way to start the server is, for example, + postmaster. The postmaster must know where to + find the data it is supposed to use. This is done with the + option. Thus, the simplest way to start the + server is: $ postmaster -D /usr/local/pgsql/data - which will leave the server running in the foreground. This must - again be done while logged into the PostgreSQL user account. Without - a , the server will try to use the data - directory in the environment variable PGDATA; if - neither of these works it will fail. + which will leave the server running in the foreground. This must be + done while logged into the PostgreSQL user + account. Without , the server will try to use + the data directory in the environment variable PGDATA. + If neither of these succeed, it will fail. @@ -187,22 +189,22 @@ $ postmaster -D /usr/local/pgsql/data $ postmaster -D /usr/local/pgsql/data > logfile 2>&1 & - It is an extremely good idea to keep the server's stdout and stderr - output around somewhere, as suggested here. It will help both for auditing - purposes and to diagnose problems. - (See for a more thorough discussion - of log file handling.) + It is an important to store the server's stdout and + stderr output somewhere, as shown above. It will help + for auditing purposes and to diagnose problems. (See for a more thorough discussion of log + file handling.) TCP/IP - The postmaster also takes a number of other command line options. - For more information see the reference page and below. - In particular, in order for the server to accept - TCP/IP connections (rather than just Unix domain socket ones), you - must also specify the option. + The postmaster also takes a number of other command line options. For + more information, see the reference page and below. In particular, in order for the + server to accept TCP/IP connections (rather than just Unix domain + socket ones), you must specify the option. @@ -210,51 +212,50 @@ $ postmaster -D /usr/local/pgsql/data > logfile 2>&1 &< pg_ctl This shell syntax can get tedious quickly. Therefore the shell - script wrapper pg_ctl is provided that - encapsulates some of the tasks. E.g., + script wrapper pg_ctl is provided to + simplify some tasks. For example: pg_ctl start -l logfile will start the server in the background and put the output into the - named log file. The option has the same - meaning as when invoking postmaster directly. - pg_ctl also implements a symmetric - stop operation. + named log file. The option has the same meaning + here as in the postmaster. pg_ctl is also + capable of stopping the server. Normally, you will want to start the database server when the - computer boots up. This is not required; the - PostgreSQL server can be run - successfully from non-privileged accounts without root - intervention. + computer boots. Auto-start scripts are operating-system specific. + There are a few distributed with + PostgreSQL in the + /contrib/start-scripts directory. This may require root + privileges. - Different systems have different conventions for starting up - daemons at boot time, so you are advised to familiarize yourself - with them. Many systems have a file + Different systems have different conventions for starting up daemons + at boot time. Many systems have a file /etc/rc.local or - /etc/rc.d/rc.local which is almost certainly - no bad place to put such a command. Whatever you do, the server - must be run by the PostgreSQL user account - and not by root or any other user. Therefore - you probably always want to form your command lines along the lines - of su -c '...' postgres, for example: + /etc/rc.d/rc.local. Others use + rc.d directories. Whatever you do, the server must be + run by the PostgreSQL user account + and not by root or any other user. Therefore you + probably should form your commands using su -c '...' + postgres. For example: su -c 'pg_ctl start -D /usr/local/pgsql/data -l serverlog' postgres - Here are a few more operating system specific suggestions. (Always - replace the proper installation directory and the user name you - chose.) + Here are a few more operating system specific suggestions. (Always + replace these with the proper installation directory and the user + name.) - For FreeBSD, take a look at the file + For FreeBSD, look at the file contrib/start-scripts/freebsd in the PostgreSQL source distribution. FreeBSD @@ -282,10 +283,9 @@ fi /usr/local/pgsql/bin/pg_ctl start -l logfile -D /usr/local/pgsql/data - to /etc/rc.d/rc.local or look into the file + to /etc/rc.d/rc.local or look at the file contrib/start-scripts/linux in the - PostgreSQL source distribution to - integrate the start and shutdown into the run level system. + PostgreSQL source distribution. @@ -294,17 +294,15 @@ fi On NetBSD, either use the FreeBSD or Linux start scripts, depending on - preference, as an example and place the file at - /usr/local/etc/rc.d/postgresql. - NetBSD + preference. NetBSD On Solaris, create a file called - /etc/init.d/postgresql to contain the following - single line: + /etc/init.d/postgresql which should contain + the following line: Solaris su - postgres -c "/usr/local/pgsql/bin/pg_ctl start -l logfile -D /usr/local/pgsql/data" @@ -319,22 +317,21 @@ su - postgres -c "/usr/local/pgsql/bin/pg_ctl start -l logfile -D /usr/local/pgs While the postmaster is running, its - PID is in the file postmaster.pid in the data - directory. This is used as an interlock against multiple postmasters - running in the same data directory, and can also be used for - shutting down the postmaster. + PID is in the file + postmaster.pid in the data directory. This is + used to prevent multiple postmasters running in the same data + directory, and can also be used for shutting down the postmaster. Server Start-up Failures - There are several common reasons for the postmaster to fail to - start up. Check the postmaster's log file, or start it by hand - (without redirecting standard output or standard error) to see - what complaint messages appear. Some of the possible error - messages are reasonably self-explanatory, but here are some that - are not. + There are several common reasons the postmaster might fail to + start. Check the postmaster's log file, or start it by hand + (without redirecting standard output or standard error) and see + what error messages appear. Some of the error messages are + self-explanatory, but some are not, as shown below: @@ -342,13 +339,12 @@ su - postgres -c "/usr/local/pgsql/bin/pg_ctl start -l logfile -D /usr/local/pgs FATAL: StreamServerPort: bind() failed: Address already in use Is another postmaster already running on that port? - This usually means just what it suggests: you tried to - start a second postmaster on the same port where one is already - running. However, if the kernel error message is not - Address already in use or some - variant of that wording, there may be a different problem. For - example, trying to start a postmaster on a reserved port number - may draw something like + This usually means just what it suggests: you tried to start + another postmaster on the same port where one is already running. + However, if the kernel error message is not Address + already in use or some variant of that, there may + be a different problem. For example, trying to start a postmaster + on a reserved port number may draw something like: $ postmaster -i -p 666 FATAL: StreamServerPort: bind() failed: Permission denied @@ -357,49 +353,48 @@ FATAL: StreamServerPort: bind() failed: Permission denied - A message like + A message like: IpcMemoryCreate: shmget(key=5440001, size=83918612, 01600) failed: Invalid argument FATAL 1: ShmemCreate: cannot create region - probably means that your kernel's limit on the size of shared - memory areas is smaller than the buffer area that PostgreSQL is - trying to create (83918612 bytes in this example). Or it could + probably means your kernel's limit on the size of shared memory is + smaller than the buffer area PostgreSQL + is trying to create (83918612 bytes in this example). Or it could mean that you don't have System-V-style shared memory support - configured into your kernel at all. As a temporary workaround, - you can try starting the postmaster with a smaller-than-normal - number of buffers ( switch). You will - eventually want to reconfigure your kernel to increase the - allowed shared memory size, however. You may see this message - when trying to start multiple postmasters on the same machine, if - their total space requests exceed the kernel limit. + configured into your kernel at all. As a temporary workaround, you + can try starting the postmaster with a smaller-than-normal number + of buffers ( switch). You will eventually want + to reconfigure your kernel to increase the allowed shared memory + size. You may see this message when trying to start multiple + postmasters on the same machine if their total space requested + exceeds the kernel limit. - An error like + An error like: IpcSemaphoreCreate: semget(key=5440026, num=16, 01600) failed: No space left on device - does not mean that you've run out of disk - space; it means that your kernel's limit on the number of System - V semaphores is smaller than the number - PostgreSQL wants to create. As above, - you may be able to work around the problem by starting the - postmaster with a reduced number of backend processes + does not mean you've run out of disk space. It + means your kernel's limit on the number of System V semaphores is + smaller than the number PostgreSQL wants + to create. As above, you may be able to work around the problem by + starting the postmaster with a reduced number of backend processes ( switch), but you'll eventually want to increase the kernel limit. - If you get an illegal system call error, then it is likely that - shared memory or semaphores are not supported at all in your kernel. In - that case your only option is to re-configure the kernel to turn on these - features. + If you get an illegal system call error, it is likely + shared memory or semaphores are not supported in your kernel at + all. In that case your only option is to reconfigure the kernel to + enable these features. - Details about configuring System V IPC facilities are given in - . + Details about configuring System V + IPC facilities are given in . @@ -407,11 +402,11 @@ IpcSemaphoreCreate: semget(key=5440026, num=16, 01600) failed: No space left on Client Connection Problems - Although the possible error conditions on the client side are - both virtually infinite and application-dependent, a few of them - might be directly related to how the server was started up. - Conditions other than those shown below should be documented with - the respective client application. + Although the error conditions possible on the client side are quite + varied and application-dependent, a few of them might be directly + related to how the server was started up. Conditions other than + those shown below should be documented with the respective client + application. @@ -428,8 +423,8 @@ psql: could not connect to server: Connection refused - Alternatively, you'll get this when attempting - Unix-socket communication to a local postmaster: + Alternatively, you'll get this when attempting Unix-socket + communication to a local postmaster: psql: could not connect to server: Connection refused Is the server running locally and accepting @@ -439,15 +434,15 @@ psql: could not connect to server: Connection refused The last line is useful in verifying that the client is trying to - connect where it is supposed to. If there is in fact no - postmaster running there, the kernel error message will typically - be either Connection refused or + connect to the right place. If there is in fact no postmaster + running there, the kernel error message will typically be either + Connection refused or No such file or directory, as - illustrated. (It is particularly important to realize that - Connection refused in this - context does not mean that the postmaster - got your connection request and rejected it -- that case will - produce a different message, as shown in Connection refused in this context + does not mean that the postmaster got your + connection request and rejected it -- that case will produce a + different message, as shown in .) Other error messages such as Connection timed out may indicate more fundamental problems, like lack of network @@ -465,35 +460,33 @@ psql: could not connect to server: Connection refused - There are a lot of configuration parameters that affect the - behavior of the database system in some way or other. Here we - describe how to set them and the following subsections will - discuss each of them. + There are a lot of configuration parameters that affect the behavior + of the database system. Here we describe how to set them and the + following subsections will discuss each in detail. All parameter names are case-insensitive. Every parameter takes a - value of one of the four types Boolean, integer, floating point, - string as described below. Boolean values are - ON, OFF, - TRUE, FALSE, - YES, NO, - 1, 0 (case-insensitive) or - any non-ambiguous prefix of these. + 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 options is to edit the file - postgresql.conf in the data directory. - (A default file is installed there.) An example of what - this file could look like is: + 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 syslog = 2 As you see, options are one per line. The equal sign between name - and value is optional. Whitespace is insignificant, blank lines + and value is optional. Whitespace is insignificant and blank lines are ignored. Hash marks (#) introduce comments anywhere. @@ -502,18 +495,17 @@ syslog = 2 SIGHUP - The configuration file is reread whenever the postmaster receives - a SIGHUP signal (which is most easily sent by means - of pg_ctl reload). The postmaster also propagates - this signal to all already-running backend processes, so that - existing sessions also get the new default. - Alternatively, you can send the signal to only one backend process - directly. + The configuration file is reread whenever the postmaster receives a + SIGHUP signal (which is most easily sent by means of + pg_ctl reload). The postmaster also propagates this + signal to all currently running backend processes so that existing + sessions also get the new value. Alternatively, you can send the + signal to a single backend process directly. A second way to set these configuration parameters is to give them - as a command line option to the postmaster, such as + as a command line option to the postmaster, such as: postmaster -c log_connections=yes -c syslog=2 @@ -532,13 +524,13 @@ env PGOPTIONS='-c geqo=off' psql (This works for any client application, not just psql.) Note that this won't work for - options that are necessarily fixed once the server is started, - such as the port number. + options that are fixed when the server is started, such as the port + number. Some options can be changed in individual SQL sessions with the - SET command, for example + SET command, for example: => SET ENABLE_SEQSCAN TO OFF; @@ -547,7 +539,7 @@ env PGOPTIONS='-c geqo=off' psql 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 set this up. + USER, respectively, are used to configure these. @@ -592,11 +584,11 @@ env PGOPTIONS='-c geqo=off' psql EFFECTIVE_CACHE_SIZE (floating point) - Sets the optimizer's assumption about the effective size of - the disk cache (that is, the portion of the kernel's disk - cache that will be used for - PostgreSQL data files). This is - measured in disk pages, which are normally 8 kB apiece. + Sets the optimizer's assumption about the effective size of the + disk cache (that is, the portion of the kernel's disk cache that + will be used for PostgreSQL data + files). This is measured in disk pages, which are normally 8 kB + each. @@ -606,7 +598,7 @@ env PGOPTIONS='-c geqo=off' psql Enables or disables the query planner's use of hash-join plan - types. The default is on. This is mostly useful to debug the + types. The default is on. This is used for debugging the query planner. @@ -621,7 +613,7 @@ env PGOPTIONS='-c geqo=off' psql Enables or disables the query planner's use of index-scan plan - types. The default is on. This is mostly useful to debug the + types. The default is on. This is used to debugging the query planner. @@ -632,7 +624,7 @@ env PGOPTIONS='-c geqo=off' psql Enables or disables the query planner's use of merge-join plan - types. The default is on. This is mostly useful to debug the + types. The default is on. This is used for debugging the query planner. @@ -642,12 +634,11 @@ env PGOPTIONS='-c geqo=off' psql 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 is any other method available. - The default is on. This is mostly useful to debug the query - planner. + 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. @@ -661,11 +652,10 @@ env PGOPTIONS='-c geqo=off' psql 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 is any other method available. - The default is on. This is mostly useful to debug the query - planner. + 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. @@ -677,8 +667,8 @@ env PGOPTIONS='-c geqo=off' psql 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 is any other method available. The default - is on. This is mostly useful to debug the query planner. + using one if there are other methods available. The default + is on. This is used for debugging the query planner. @@ -688,7 +678,7 @@ env PGOPTIONS='-c geqo=off' psql Enables or disables the query planner's use of TID scan plan - types. The default is on. This is mostly useful to debug the + types. The default is on. This is used for debugging the query planner. @@ -707,9 +697,9 @@ env PGOPTIONS='-c geqo=off' psql Enables or disables genetic query optimization, which is an - algorithm that attempts to do query planning without - exhaustive search. This is on by default. See also the various - other GEQO_ settings. + algorithm that attempts to do query planning without exhaustive + searching. This is on by default. See also the various other + GEQO_ settings. @@ -724,20 +714,20 @@ env PGOPTIONS='-c geqo=off' psql Various tuning parameters for the genetic query optimization algorithm: The pool size is the number of individuals in one - population. Valid values are between 128 and 1024. If it is - set to 0 (the default) a pool size of 2^(QS+1), where QS - is the number of FROM items in the query, is taken. The effort - is used to calculate a default for generations. Valid values - are between 1 and 80, 40 being the default. Generations - specifies the number of iterations in the algorithm. The - number must be a positive integer. If 0 is specified then - Effort * Log2(PoolSize) is used. The run time of the algorithm - is roughly proportional to the sum of pool size and - generations. The selection bias is the selective pressure - within the population. Values can be from 1.50 to 2.00; the - latter is the default. The random seed can be set to get - reproducible results from the algorithm. If it is set to -1 - then the algorithm behaves non-deterministically. + population. Valid values are between 128 and 1024. If it is set + to 0 (the default) a pool size of 2^(QS+1), where QS is the + number of FROM items in the query, is taken. The effort is used + to calculate a default for generations. Valid values are between + 1 and 80, 40 being the default. Generations specifies the number + of iterations in the algorithm. The number must be a positive + integer. If 0 is specified then Effort * + Log2(PoolSize) is used. The run time of the algorithm + is roughly proportional to the sum of pool size and generations. + The selection bias is the selective pressure within the + population. Values can be from 1.50 to 2.00; the latter is the + default. The random seed can be set to get reproducible results + from the algorithm. If it is set to -1 then the algorithm + behaves non-deterministically. @@ -747,11 +737,11 @@ env PGOPTIONS='-c geqo=off' psql Use genetic query optimization to plan queries with at least - this many FROM items involved. (Note that a JOIN construct - counts as only one FROM item.) The default is 11. For simpler - queries it is usually best to use the - deterministic, exhaustive planner. This parameter also controls - how hard the optimizer will try to merge subquery + this many FROM items involved. (Note that a + JOIN construct counts as only one FROM + item.) The default is 11. For simpler queries it is usually best + to use the deterministic, exhaustive planner. This parameter + also controls how hard the optimizer will try to merge subquery FROM clauses into the upper query. @@ -763,22 +753,23 @@ env PGOPTIONS='-c geqo=off' psql The Key Set Query Optimizer (KSQO) causes the query planner to convert - queries whose WHERE clause contains many OR'ed AND clauses - (such as WHERE (a=1 AND b=2) OR (a=2 AND b=3) + queries whose WHERE clause contains many OR'ed AND + clauses (such as WHERE (a=1 AND b=2) OR (a=2 AND b=3) ...) into a union query. This method can be faster - than the default implementation, but it doesn't necessarily - give exactly the same results, since UNION implicitly adds a - SELECT DISTINCT clause to eliminate identical output rows. - KSQO is commonly used when working with products like - Microsoft Access, which tend to - generate queries of this form. + than the default implementation, but it doesn't necessarily give + exactly the same results, since UNION implicitly + adds a SELECT DISTINCT clause to eliminate identical + output rows. KSQO is commonly used when + working with products like Microsoft + Access, which tend to generate queries of this + form. - The KSQO algorithm used to be absolutely essential for queries - with many OR'ed AND clauses, but in + The KSQO algorithm used to be absolutely + essential for queries with many OR'ed AND clauses, but in PostgreSQL 7.0 and later the standard - planner handles these queries fairly successfully. Hence the + planner handles these queries fairly successfully; hence the default is off. @@ -789,8 +780,8 @@ env PGOPTIONS='-c geqo=off' psql Sets the query optimizer'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. + nonsequentially fetched disk page. This is measured as a + multiple of the cost of a sequential page fetch. @@ -799,7 +790,7 @@ env PGOPTIONS='-c geqo=off' psql - Unfortunately, there is no well-defined method of determining + Unfortunately, there is no well-defined method for determining ideal values for the family of COST variables that were just described. You are encouraged to experiment and share your findings. @@ -850,13 +841,14 @@ env PGOPTIONS='-c geqo=off' psql Turns on various assertion checks. This is a debugging aid. If - you are experiencing strange problems or crashes you might - want to turn this on, as it might expose programming mistakes. - To use this option, the macro USE_ASSERT_CHECKING - must be defined when PostgreSQL is built (see the configure option - --enable-cassert). Note that - DEBUG_ASSERTIONS defaults to on if PostgreSQL - has been built this way. + you are experiencing strange problems or crashes you might want + to turn this on, as it might expose programming mistakes. To use + this option, the macro USE_ASSERT_CHECKING + must be defined when PostgreSQL is + built (see the configure option + --enable-cassert). Note that + DEBUG_ASSERTIONS defaults to on if + PostgreSQL has been built this way. @@ -874,8 +866,6 @@ env PGOPTIONS='-c geqo=off' psql the resulting parse tree, the query rewriter output, or the execution plan. indents these displays to produce a more readable but much longer output format. - Setting above zero implicitly turns - on some of these flags. @@ -897,11 +887,10 @@ env PGOPTIONS='-c geqo=off' psql LOG_CONNECTIONS (boolean) - Prints a line informing about each successful connection in - the server log. 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. + 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. @@ -948,7 +937,7 @@ env PGOPTIONS='-c geqo=off' psql Shows the outgoing port number of the connecting host in the connection log messages. You could trace back the port number to find out what user initiated the connection. Other than - that it's pretty useless and therefore off by default. This + that, it's pretty useless and therefore off by default. This option can only be set at server start. @@ -974,9 +963,9 @@ env PGOPTIONS='-c geqo=off' psql 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. + is restarted. If off, statistics are accumulated across server + restarts. The default is on. This option can only be set at + server start. @@ -998,12 +987,13 @@ env PGOPTIONS='-c geqo=off' psql PostgreSQL allows the use of - syslog for logging. If this option - is set to 1, messages go both to syslog and the standard - output. A setting of 2 sends output only to syslog. (Some - messages will still go to the standard output/error.) The - default is 0, which means syslog is off. This option must be - set at server start. + syslog for logging. If this option is + set to 1, messages go both to syslog and the + standard output. A setting of 2 sends output only to + syslog. (Some messages will still go to the + standard output/error.) The default is 0, which means + syslog is off. This option must be set at server + start. To use syslog, the build of @@ -1018,11 +1008,11 @@ env PGOPTIONS='-c geqo=off' psql This option determines the syslog - facility to be used when syslog is enabled. - 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. + facility to be used when + syslog is enabled. 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. @@ -1031,11 +1021,11 @@ env PGOPTIONS='-c geqo=off' psql SYSLOG_IDENT (string) - If logging to syslog is enabled, this option determines the - program name used to identify + If logging to syslog is enabled, this option + determines the program name used to identify PostgreSQL messages in - syslog log messages. The default - is postgres. + syslog log messages. The default is + postgres. @@ -1077,12 +1067,12 @@ env PGOPTIONS='-c geqo=off' psql timeoutauthentication - 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 unceremoniously 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. + 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. @@ -1101,21 +1091,20 @@ env PGOPTIONS='-c geqo=off' psql This is the amount of time, in milliseconds, to wait on a lock - before checking to see if there is a deadlock condition or not. - The check for deadlock is relatively slow, so we don't want to - run it every time we wait for a lock. We (optimistically?) - assume that deadlocks are not common in production applications, - and just wait on the lock for awhile before starting to ask - questions about whether it can ever get unlocked. - 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 the lock will be released before the waiter decides to - check for deadlock. - This option can only be set at server start. + 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 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 the lock will be released before + the waiter decides to check for deadlock. This option can only + be set at server start. @@ -1128,11 +1117,10 @@ env PGOPTIONS='-c geqo=off' psql DEFAULT_TRANSACTION_ISOLATION (string) - Each SQL transaction has an isolation level, which can be - either read committed or - serializable. This parameter controls what the - isolation level of each new transaction is set to. The - default is read committed. + Each SQL transaction has an isolation level, which can be either + read committed or serializable. + This parameter controls the default isolation level of each new + transaction. The default is read committed/quote>. @@ -1150,7 +1138,7 @@ env PGOPTIONS='-c geqo=off' psql If a dynamically loadable module needs to be opened and the - specified name does not have a directory component (i.e., the + specified name does not have a directory component (i.e. the name does not contain a slash), the system will search this path for the specified file. (The name that is used is the name specified in the CREATE FUNCTION or @@ -1159,12 +1147,14 @@ env PGOPTIONS='-c geqo=off' psql The value for dynamic_library_path has to be a colon-separated - list of absolute directory names. If a directory name starts + list of absolute directory names. If a directory name starts with the special value $libdir, the - compiled-in PostgreSQL package library directory, which is where the - modules provided by the PostgreSQL distribution are installed, - is substituted. (Use pg_config --pkglibdir - to print the name of this directory.) An example value: + compiled-in PostgreSQL package + library directory is substituted. This where the modules + provided by the PostgreSQL + distribution are installed. (Use pg_config + --pkglibdir to print the name of this directory.) For + example: dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' @@ -1174,17 +1164,17 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' The default value for this parameter is - $libdir. If the value is set to the empty + $libdir. If the value is set to an empty string, the automatic path search is turned off. - This parameter can be changed at run time by superusers, but - note that a setting done that way will only persist till the - end of the client connection, so this method should be - reserved for development purposes. The recommended way to set - this parameter is in the postgresql.conf - configuration file. + This parameter can be changed at run time by superusers, but a + setting done that way will only persist until the end of the + client connection, so this method should be reserved for + development purposes. The recommended way to set this parameter + is in the postgresql.conf configuration + file. @@ -1198,44 +1188,42 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' If this option is on, the PostgreSQL backend - will use the fsync() system call in several - places to make sure that updates are physically written to - disk and do not hang around in the kernel buffer cache. This - increases the chance by a large amount that a database - installation will still be usable after an operating system or - hardware crash. (Crashes of the database server itself do - not affect this consideration.) + will use the fsync() system call in several places + to make sure that updates are physically written to disk. This + insures that a database installation will recover to a + consistent state after an operating system or hardware crash. + (Crashes of the database server itself are not + related to this.) - However, this operation slows down PostgreSQL, - because at all those points it has - to block and wait for the operating system to flush the - buffers. Without fsync, the operating system is - allowed to do its best in buffering, sorting, and delaying - writes, which can make for a considerable performance - increase. 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. + However, this operation does slow down + PostgreSQL because at transaction commit it has + wait for the operating system to flush the write-ahead log. + Without fsync, the operating system is allowed to + do its best in buffering, sorting, and delaying writes, which + can considerably increase 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. - This option is the subject of an eternal debate in the - PostgreSQL user and developer communities. Some - always leave it off, some turn it off only for bulk loads, - where there is a clear restart point if something goes wrong, - some leave it on just to be on the safe side. Because it is - the safe side, on is also the default. If you trust your - operating system, your hardware, and your utility company (or - better your UPS), you might want to disable fsync. + For the above reasons, some administrators always leave it off, + some turn it off only for bulk loads, where there is a clear + restart point if something goes wrong, and some leave it on just + to be on the safe side. Because it is always safe, the default + is on. If you trust your operating system, your hardware, and + your utility company (or better your UPS), you might want to + disable fsync. - It should be noted that the performance penalty from doing - fsyncs is considerably less in PostgreSQL version - 7.1 than it was in prior releases. If you previously suppressed - fsyncs because of performance problems, you may wish to reconsider - your choice. + It should be noted that the performance penalty of doing + fsyncs is considerably less in + PostgreSQL version 7.1 and later. If you + previously suppressed fsyncs for performance + reasons, you may wish to reconsider your choice. @@ -1259,9 +1247,10 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' MAX_CONNECTIONS (integer) - Determines how many concurrent connections the database server - will allow. The default is 32 (unless altered while building - the server). This parameter can only be set at server start. + Determines the maximum number of concurrent connections to the + database server. The default is 32 (unless altered while + building the server). This parameter can only be set at server + start. @@ -1270,11 +1259,10 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' MAX_EXPR_DEPTH (integer) - Sets the maximum expression nesting depth that the parser will - accept. The default value is high enough for any normal query, - but you can raise it if you need to. (But if you raise it too - high, you run the risk of backend crashes due to stack - overflow.) + Sets the maximum expression nesting depth of the parser. The + default value is high enough for any normal query, but you can + raise it if needed. (But if you raise it too high, you run + the risk of backend crashes due to stack overflow.) @@ -1283,21 +1271,20 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' MAX_FILES_PER_PROCESS (integer) - Sets the maximum number of simultaneously open files in each server - subprocess. The default is 1000. The limit actually used by the code - is the smaller of this setting and the result of - sysconf(_SC_OPEN_MAX). - Therefore, on systems where sysconf returns a reasonable limit, - you don't need to worry about this setting. But on some platforms - (notably, most BSD systems), sysconf returns a value that is much - larger than the system can really support when a large number of - processes all try to open that many files. If you find yourself - seeing Too many open files failures, try reducing this - setting. - This option can only be set at server start or in the - postgresql.conf configuration file; - if changed in the configuration file, it only affects - subsequently-started server subprocesses. + Sets the maximum number of simultaneously open files in each + server subprocess. The default is 1000. The limit actually used + by the code is the smaller of this setting and the result of + sysconf(_SC_OPEN_MAX). Therefore, on systems + where sysconf returns a reasonable limit, you don't + need to worry about this setting. But on some platforms + (notably, most BSD systems), sysconf returns a + value that is much larger than the system can really support + when a large number of processes all try to open that many + files. If you find yourself seeing Too many open files + failures, try reducing this setting. This option can only be set + at server start or in the postgresql.conf + configuration file; if changed in the configuration file, it + only affects subsequently-started server subprocesses. @@ -1306,9 +1293,9 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' MAX_FSM_RELATIONS (integer) - Sets the maximum number of relations (tables) for which free space - will be tracked in the shared free-space map. - The default is 100. This option can only be set at server start. + Sets the maximum number of relations (tables) for which free + space will be tracked in the shared free-space map. The default + is 100. This option can only be set at server start. @@ -1317,9 +1304,9 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' MAX_FSM_PAGES (integer) - Sets the maximum number of disk pages for which free space - will be tracked in the shared free-space map. - The default is 10000. This option can only be set at server start. + Sets the maximum number of disk pages for which free space will + be tracked in the shared free-space map. The default is 10000. + This option can only be set at server start. @@ -1329,11 +1316,12 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' 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. + max_locks_per_transaction * + max_connections distinct objects will need to + be locked at any one time. The default, 64, which 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. @@ -1343,11 +1331,10 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' When a password is specified in CREATE USER or - ALTER USER without writing either ENCRYPTED or - UNENCRYPTED, this flag determines whether the password is to be - encrypted. - The default is off (do not encrypt the password), but this choice - may change in a future release. + ALTER USER without writing either ENCRYPTED or + UNENCRYPTED, this flag determines whether the password is to be + encrypted. The default is off (do not encrypt the password), but + this choice may change in a future release. @@ -1367,9 +1354,9 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' SHARED_BUFFERS (integer) - Sets the number of shared memory buffers the database server - will use. The default is 64. Each buffer is typically 8192 - bytes. This option can only be set at server start. + Sets the number of shared memory buffers used by the database + server. The default is 64. Each buffer is typically 8192 bytes. + This option can only be set at server start. @@ -1378,13 +1365,13 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' SILENT_MODE (bool) - Runs postmaster silently. If this option is set, postmaster + Runs postmaster silently. If this option is set, the postmaster will automatically run in background and any controlling ttys - are disassociated, thus no messages are written to standard output or - standard error (same effect as postmaster's -S option). Unless some - logging system such as syslog is enabled, using this option is - discouraged since it makes it impossible to see error - messages. + are disassociated, thus no messages are written to standard + output or standard error (same effect as postmaster's -S + option). Unless some logging system such as + syslog is enabled, using this option is + discouraged since it makes it impossible to see error messages. @@ -1393,15 +1380,15 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' SORT_MEM (integer) - Specifies the amount of memory to be used by internal sorts - and hashes before switching to temporary disk files. The value - is specified in kilobytes, and defaults to 512 kilobytes. Note - that for a complex query, several sorts and/or hashes might be - running in parallel, and each one will be allowed to use as - much memory as this value specifies before it starts to put - data into temporary files. And don't forget that each running - backend could be doing one or more sorts. So the total memory - space needed could be many times the value of SORT_MEM. + Specifies the amount of memory to be used by internal sorts and + hashes before switching to temporary disk files. The value is + specified in kilobytes, and defaults to 512 kilobytes. Note that + for a complex query, several sorts and/or hashes might be + running in parallel, and each one will be allowed to use as much + memory as this value specifies before it starts to put data into + temporary files. Also, each running backend could be doing one + or more sorts simultaneously, so the total memory used could be + many times the value of SORT_MEM. @@ -1412,14 +1399,13 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' This controls the inheritance semantics, in particular whether - subtables are included into the consideration of various - commands by default. This was not the case in versions prior - to 7.1. If you need the old behavior you can set this - variable to off, but in the long run you are encouraged to - change your applications to use the ONLY - keyword to exclude subtables. See the SQL language reference - and the User's Guide for more - information about inheritance. + subtables are included by various commands by default. They were + not included in versions prior to 7.1. If you need the old + behavior you can set this variable to off, but in the long run + you are encouraged to change your applications to use the + ONLY keyword to exclude subtables. See the + SQL language reference and the User's + Guide for more information about inheritance. @@ -1443,10 +1429,10 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' TCPIP_SOCKET (boolean) - If this is true, then the server will accept TCP/IP - connections. Otherwise only local Unix domain socket - connections are accepted. It is off by default. This option - can only be set at server start. + If this is true, then the server will accept TCP/IP connections. + Otherwise only local Unix domain socket connections are + accepted. It is off by default. This option can only be set at + server start. @@ -1457,13 +1443,13 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' When turned on, expressions of the form - expr = NULL (or - NULL = expr) are treated as + expr = NULL (or NULL + = expr) are treated as expr IS NULL, that is, they - return true if expr evaluates to the NULL - value, and false otherwise. The correct behavior of + return true if expr evaluates to the NULL value, + and false otherwise. The correct behavior of expr = NULL is to always - return NULL (unknown). Therefore this option defaults to off. + return NULL (unknown). Therefore this option defaults to off. @@ -1477,7 +1463,7 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' very useful and do not appear often in normal applications, so this option does little harm in practice. But new users are frequently confused about the semantics of expressions - involving NULL, so we do not turn this option on by default. + involving NULL, so this option is not on by default. @@ -1538,16 +1524,16 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' The default permissions are 0777, meaning - anyone can connect. Reasonable alternatives would be + anyone can connect. Reasonable alternatives are 0770 (only user and group, see also under - ) and - 0700 (only user). (Note that actually for - a Unix socket, only write permission matters and there is no - point in setting or revoking read or execute permissions.) + ) and 0700 + (only user). (Note that actually for a Unix socket, only write + permission matters and there is no point in setting or revoking + read or execute permissions.) - This access control mechanism is independent from the one + This access control mechanism is independent of the one described in . @@ -1562,10 +1548,10 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' Specifies the maximum amount of memory to be used by - VACUUM to keep track of to-be-reclaimed tuples. - The value is specified in kilobytes, and defaults to 8192 kilobytes. - Larger settings may improve the speed of vacuuming large tables - that have many deleted tuples. + VACUUM to keep track of to-be-reclaimed + tuples. The value is specified in kilobytes, and defaults to + 8192 kilobytes. Larger settings may improve the speed of + vacuuming large tables that have many deleted tuples. @@ -1576,8 +1562,9 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' Specifies the TCP/IP host name or address on which the postmaster is to listen for - connections from client applications. Defaults to - listening on all configured addresses (including localhost). + connections from client applications. Defaults to listening on + all configured addresses (including localhost). @@ -1622,14 +1609,15 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' Time delay between writing a commit record to the WAL buffer and - flushing the buffer out to disk, in microseconds. A nonzero delay - allows 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 time 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 backend has - written its commit record. + flushing the buffer out to disk, in microseconds. A nonzero + delay allows multiple transactions to be committed with only one + fsync system call, if system load is high + enough additional transactions may 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 backend has written its commit + record. @@ -1639,9 +1627,9 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' Minimum number of concurrent open transactions to require before - performing the COMMIT_DELAY delay. A larger value makes it more - probable that at least one other transaction will become ready to - commit during the delay interval. + performing the COMMIT_DELAY delay. A larger value + makes it more probable that at least one other transaction will + become ready to commit during the delay interval. @@ -1650,7 +1638,7 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' WAL_BUFFERS (integer) - Number of disk-page buffers in shared memory for WAL log. + Number of disk-page buffers in shared memory for WAL logging. This option can only be set at server start. @@ -1724,7 +1712,7 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' - debug_level = x + server_min_messages = DEBUGx @@ -1806,11 +1794,11 @@ $ postmaster -o '-S 1024 -s' Managing Kernel Resources - A large PostgreSQL installation can quickly hit + A large PostgreSQL installation can quickly exhaust various operating system resource limits. (On some systems, the factory defaults are so low that you don't even need a really large installation.) If you have encountered this kind of - problem then keep reading. + problem, keep reading. @@ -1826,13 +1814,14 @@ $ postmaster -o '-S 1024 -s' Shared memory and semaphores are collectively referred to as - System V IPC (together with message queues, which are - not relevant for PostgreSQL). Almost all modern + System V + IPC (together with message queues, which are not + relevant for PostgreSQL). Almost all modern operating systems provide these features, but not all of them have - them turned on or sufficiently sized by default, especially - systems with BSD heritage. (For the QNX and BeOS ports, - PostgreSQL provides its own replacement - implementation of these facilities.) + them turned on or sufficiently sized by default, especially systems + with BSD heritage. (For the QNX and + BeOS ports, PostgreSQL + provides its own replacement implementation of these facilities.) @@ -1844,17 +1833,15 @@ $ postmaster -o '-S 1024 -s' When PostgreSQL exceeds one of the various hard - limits of the IPC resources then the postmaster will refuse to - start up and should leave a marginally instructive error message - about which problem was encountered and what needs to be done - about it. (See also .) - The relevant kernel parameters are named - consistently across different systems; gives an overview. The methods to - set them, however, vary; suggestions for some platforms are given - below. Be warned that it is often necessary to reboot your - machine at least, possibly even recompile the kernel, to change these - settings. + IPC limits, the postmaster will refuse to start and + should leave an instructive error message describing the problem + encountered and what to do about it. (See also .) The relevant kernel + parameters are named consistently across different systems; gives an overview. The methods to set + them, however, vary. Suggestions for some platforms are given below. + Be warned that it is often necessary to reboot your machine, and + possibly even recompile the kernel, to change these settings. @@ -1937,27 +1924,26 @@ $ postmaster -o '-S 1024 -s' - SHMMAX - The most important shared memory parameter is SHMMAX, - the maximum size, in bytes, that a shared memory segment can have. - If you get an error message from shmget along the - lines of Invalid argument then it is possible that - this limit has been exceeded. The size of the required shared - memory segments varies both with the number of requested buffers - ( Less likely to cause problems is the minimum size for shared memory segments (SHMMIN), which should be at most - somewhere around 256 kB for PostgreSQL (it is + approximately 256 kB for PostgreSQL (it is usually just 1). The maximum number of segments system-wide (SHMMNI) or per-process (SHMSEG) should not cause a problem unless your system has them set to zero. Some @@ -1984,16 +1970,16 @@ $ postmaster -o '-S 1024 -s' - In some cases it might also turn out to be necessary to increase + In some cases it might also be necessary to increase SEMMAP to be at least on the order of - SEMMNS. This parameter defines the size of the - semaphore resource map, in which each contiguous block of available - semaphores needs an entry. When a semaphore set is freed it is - either added to an existing entry that is adjacent to the freed - block or it is registered under a new map entry. If the map is - full, the freed semaphores get lost (until reboot). Fragmentation - of the semaphore space could therefore over time lead to less - available semaphores than there should be. + SEMMNS. This parameter defines the size of the semaphore + resource map, in which each contiguous block of available semaphores + needs an entry. When a semaphore set is freed it is either added to + an existing entry that is adjacent to the freed block or it is + registered under a new map entry. If the map is full, the freed + semaphores get lost (until reboot). Fragmentation of the semaphore + space could over time lead to fewer available semaphores than there + should be. @@ -2021,12 +2007,11 @@ $ postmaster -o '-S 1024 -s' By default, only 4 MB of shared memory is supported. Keep in mind that shared memory is not pageable; it is locked in RAM. - - To increase the number of shared buffers supported by the - postmaster, add the following to your kernel configuration file. A - SHMALL value of 1024 represents 4MB of shared - memory. The following increases the maximum shared memory area - to 32 MB: + To increase the number of shared buffers supported by the + postmaster, add the following to your kernel configuration + file. A SHMALL value of 1024 represents 4MB of + shared memory. The following increases the maximum shared + memory area to 32 MB: options "SHMALL=8192" options "SHMMAX=\(SHMALL*PAGE_SIZE\)" @@ -2057,9 +2042,9 @@ options "SYSPTSIZE=16" Semaphores</> <para> - You may need to increase the number of semaphores. By - default, <productname>PostgreSQL</> allocates 34 semaphores, - which is over half the default system total of 60. + You may need to increase the number of semaphores. By default, + <productname>PostgreSQL</> allocates 34 semaphores, which is + over half the default system total of 60. </para> </formalpara> @@ -2105,6 +2090,10 @@ options SEMMAP=256 class="osname">OpenBSD</> the key word is actually <literal>option</literal> singular.) </para> + <para> + You may also want to use the <application>sysctl</> setting to + lock shared memory into RAM and prevent it from being paged out + to swap. </listitem> </varlistentry> @@ -2123,8 +2112,8 @@ options SEMMAP=256 <acronym>IPC</> parameters can be set in the <application>System Administration Manager</> (<acronym>SAM</>) under <menuchoice><guimenu>Kernel - Configuration</><guimenuitem>Configurable Parameters</></>. - Hit <guibutton>Create A New Kernel</> when you're done. + Configuration</><guimenuitem>Configurable Parameters</></>. Hit + <guibutton>Create A New Kernel</> when you're done. </para> </listitem> </varlistentry> @@ -2164,10 +2153,10 @@ kernel.shmmax = 134217728 </para> <para> - Other parameters are sufficiently sized for any application. - If you want to see for yourself look into - <filename>/usr/src/linux/include/asm-<replaceable>xxx</>/shmparam.h</> - and <filename>/usr/src/linux/include/linux/sem.h</>. + Other parameters are sufficiently sized for any application. If + you want to see for yourself look in + <filename>/usr/src/linux/include/asm-<replaceable>xxx</>/shmpara + m.h</> and <filename>/usr/src/linux/include/linux/sem.h</>. </para> </listitem> </varlistentry> @@ -2180,7 +2169,7 @@ kernel.shmmax = 134217728 <para> In the default configuration, only 512 kB of shared memory per segment is allowed, which is about enough for <option>-B 24 -N - 12</>. To increase the setting, first change the directory to + 12</>. To increase the setting, first change directory to <filename>/etc/conf/cf.d</>. To display the current value of <varname>SHMMAX</>, in bytes, run <programlisting> @@ -2206,8 +2195,8 @@ kernel.shmmax = 134217728 <indexterm><primary>Solaris</></> <listitem> <para> - At least in version 2.6, the maximum size of a shared memory - segment is set too low for <productname>PostgreSQL</>. The + At least in version 2.6, the default maximum size of a shared + memory segments is too low for <productname>PostgreSQL</>. The relevant settings can be changed in <filename>/etc/system</>, for example: <programlisting> @@ -2221,7 +2210,7 @@ set semsys:seminfo_semmni=512 set semsys:seminfo_semmns=512 set semsys:seminfo_semmsl=32 </programlisting> - You need to reboot to make the changes effective. + You need to reboot for the changes to take effect. </para> <para> @@ -2273,27 +2262,26 @@ set semsys:seminfo_semmsl=32 <title>Resource Limits - Unix-like operating systems enforce various kinds of resource - limits that might interfere with the operation of your - PostgreSQL server. Of importance are - especially the limits on the number of processes per user, the - number of open files per process, and the amount of memory - available to a process. Each of these have a hard - and a soft limit. The soft limit is what actually - counts but it can be changed by the user up to the hard limit. - The hard limit can only be changed by the root user. The system - call setrlimit is responsible for setting - these parameters. The shell's built-in command - ulimit (Bourne shells) or - limit (csh) is used to control the resource - limits from the command line. On BSD-derived systems the file - /etc/login.conf controls what values the - various resource limits are set to upon login. See + Unix-like operating systems enforce various kinds of resource limits + that might interfere with the operation of your + PostgreSQL server. Of particular + importance are limits on the number of processes per user, the + number of open files per process, and the amount of memory available + to each process. Each of these have a hard and a + soft limit. The soft limit is what actually counts + but it can be changed by the user up to the hard limit. The hard + limit can only be changed by the root user. The system call + setrlimit is responsible for setting these + parameters. The shell's built-in command ulimit + (Bourne shells) or limit (csh) is + used to control the resource limits from the command line. On + BSD-derived systems the file /etc/login.conf + controls the various resource limits set during login. See login.conf - 5 for details. The relevant + 5 for details. The relevant parameters are maxproc, - openfiles, and datasize. - For example: + openfiles, and datasize. For + example: default:\ ... @@ -2307,8 +2295,7 @@ default:\ - Kernels generally also have an implementation-dependent - system-wide limit on some resources. + Kernels can also have system-wide limits on some resources. @@ -2345,12 +2332,12 @@ default:\ On the other side of the coin, some systems allow individual - processes to open large numbers of files; if more than a few processes - do so then the system-wide limit can easily be exceeded. If you find - this happening, and don't want to alter the system-wide limit, you - can set PostgreSQL's - max_files_per_process configuration parameter - to limit its consumption of open files. + processes to open large numbers of files; if more than a few + processes do so then the system-wide limit can easily be exceeded. + If you find this happening, and don't want to alter the system-wide + limit, you can set PostgreSQL's + max_files_per_process configuration parameter to + limit the consumption of open files. @@ -2361,19 +2348,19 @@ default:\ Shutting down the server - Depending on your needs, there are several ways to shut down the - database server when your work is done. The differentiation is - done by what signal you send to the server process. + There are several ways to shut down the database server. You control + the type of shutdown by sending different signals to the server + process. SIGTERM - After receiving SIGTERM, the postmaster disallows new - connections, but lets existing backends end their work normally. - It shuts down only after all of the backends terminate by client - request. - This is the Smart Shutdown. + After receiving SIGTERM, the postmaster + disallows new connections, but lets existing backends end their + work normally. It shuts down only after all of the backends + terminate normally. This is Smart + Shutdown. @@ -2383,10 +2370,10 @@ default:\ The postmaster disallows new connections and sends all existing - backends SIGTERM, which will cause them to abort their current - transactions and exit promptly. It then waits for the backends to exit - and finally shuts down the data base. - This is the Fast Shutdown. + backends SIGTERM, which will cause them + to abort their current transactions and exit promptly. It then + waits for the backends to exit and finally shuts down. This is + Fast Shutdown. @@ -2394,13 +2381,14 @@ default:\ SIGQUIT - - This is the Immediate Shutdown which - will cause the postmaster to send a SIGQUIT to all backends and - exit immediately (without properly shutting down the database - system). The backends likewise exit immediately upon receiving - SIGQUIT. This will lead to recovery (by replaying the WAL log) - upon next start-up. This is recommended only in emergencies. + This is Immediate Shutdown, which + will cause the postmaster to send a + SIGQUIT to all backends and exit + immediately (without properly shutting itself down). The backends + likewise exit immediately upon receiving + SIGQUIT. This will lead to recovery (by + replaying the WAL log) upon next start-up. This is recommended + only in emergencies. @@ -2408,9 +2396,10 @@ default:\ - It is best not to use SIGKILL to shut down the postmaster. This - will prevent the postmaster from releasing shared memory and - semaphores, which you may then have to do by hand. + It is best not to use SIGKILL to shut down + the postmaster. This will prevent the postmaster from releasing + shared memory and semaphores, which may then have to be done by + manually. @@ -2437,11 +2426,11 @@ $ kill -INT `head -1 /usr/local/pgsql/data/postmaster.pid` - PostgreSQL has native support for connections over - SSL to encrypt - client/server communications for increased security. This requires - OpenSSL to be installed on both client - and server systems and support enabled at build time (see PostgreSQL has native support for using + SSL connections to encrypt client/server communications + for increased security. This requires + OpenSSL be installed on both client and + server systems and support enabled at build time (see ). @@ -2458,30 +2447,30 @@ $ kill -INT `head -1 /usr/local/pgsql/data/postmaster.pid` - The server will listen for both standard and SSL connections - on the same TCP/IP port, and will negotiate with any connecting - client whether or not to use SSL. - See - about how to force on the server side the use of SSL for certain - connections. + The server will listen for both standard and SSL connections on the + same TCP/IP port, and will negotiate with any connecting client on + whether to use SSL. See about + how to force the server to only use of SSL for certain connections. For details on how to create your server private key and certificate, - refer to the OpenSSL documentation. A simple self-signed - certificate can be used to get started for testing, but a certificate signed - by a CA (either one of the global CAs or a local one) should be used in - production so the client can verify the server's identity. To create - a quick self-signed certificate, use the following OpenSSL command: + refer to the OpenSSL documentation. A simple + self-signed certificate can be used to get started for testing, but a + certificate signed by a CA (either one of the global + CAs or a local one) should be used in production so the + client can verify the server's identity. To create a quick + self-signed certificate, use the following + OpenSSL command: openssl req -new -text -out cert.req - Fill out the information that openssl asks for. Make sure that you enter - the local host name as Common Name; the challenge password can be - left blank. The script will generate a key that is passphrase protected; - it will not accept a pass phrase that is less than four characters long. - To remove the passphrase (as you must if you want automatic start-up of - the server), run the commands + Fill out the information that openssl asks for. Make sure + that you enter the local host name as Common Name; the challenge + password can be left blank. The script will generate a key that is + passphrase protected; it will not accept a pass phrase that is less + than four characters long. To remove the passphrase (as you must if + you want automatic start-up of the server), run the commands openssl rsa -in privkey.pem -out cert.pem @@ -2523,8 +2512,8 @@ cp cert.cert $PGDATA/server.crt First make sure that an ssh server is running properly on the same machine as PostgreSQL and that you can log in using - ssh as some user. Then you can establish a secure tunnel with a - command like this from the client machine: + ssh as some user. Then you can establish a secure + tunnel with a command like this from the client machine: $ ssh -L 3333:foo.com:5432 joe@foo.com @@ -2541,8 +2530,9 @@ psql -h localhost -p 3333 template1 To the database server it will then look as though you are really user joe@foo.com and it will use whatever authentication procedure was set up for this user. In order for the - tunnel setup to succeed you must be allowed to connect via ssh as - joe@foo.com, just as if you had attempted to use ssh to set up a + tunnel setup to succeed you must be allowed to connect via + ssh as joe@foo.com, just + as if you had attempted to use ssh to set up a terminal session. diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 3b59cbec63..fa1ca8459e 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -2,19 +2,23 @@ # PostgreSQL configuration file # ----------------------------- # -# This file consists of lines of the form +# This file consists of lines of the form: # # name = value # -# (The `=' is optional.) White space is collapsed, comments are -# introduced by `#' anywhere on a line. The complete list of option -# names and allowed values can be found in the PostgreSQL -# documentation. The commented-out settings shown in this file -# represent the default values. - +# (The '=' is optional.) White space may be used. Comments are introduced +# with '#' anywhere on a line. The complete list of option names and +# allowed values can be found in the PostgreSQL documentation. The +# commented-out settings shown in this file represent the default values. +# # Any option can also be given as a command line switch to the -# postmaster, e.g., 'postmaster -c log_connections=on'. Some options +# postmaster, e.g. 'postmaster -c log_connections=on'. Some options # can be changed at run-time with the 'SET' SQL command. +# +# This file is read on postmaster startup and when the postmaster +# receives a SIGHUP. If you edit the file on a running system, you have +# to SIGHUP the postmaster for the changes to take effect, or use +# "pg_ctl reload". #========================================================================