What changed?

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 (ISO, Postgres, SQL, or German) and the date field order specification (DMY, MDY, or YMD). 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 8.5 for more information. The default is ISO, MDY.
+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 (ISO, Postgres, SQL, or German) and the input/output specification for year/month/day ordering (DMY, MDY, or YMD). 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 8.5 for more information. The default is ISO, MDY.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 8.5 for more information.
+Sets the time zone for displaying and interpreting time stamps. The default is 'unknown', which means to use whatever the system environment specifies as the time zone. See Section 8.5 for more information.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-When true, tables that are referenced by a query will be automatically added to the FROM clause if not already present. The default is true for compatibility with previous releases of PostgreSQL. However, this behavior is not SQL-standard, and many people dislike it because it can mask mistakes. Set to false for the SQL-standard behavior of rejecting references to tables that are not listed in FROM.
+When true, tables that are referenced by a query will be automatically added to the FROM clause if not already present. The default is true for compatibility with previous releases of PostgreSQL. However, this behavior is not SQL-standard, and many people dislike it because it can mask mistakes (such as referencing a table where you should have referenced its alias). Set to false for the SQL-standard behavior of rejecting references to tables that are not listed in FROM.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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 22.3.1. 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 if and only if it succeeds. Examples: archive_command = 'cp "%p" /mnt/server/archivedir/"%f"' archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Windows

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+In each round, no more than this many dirty buffers will be written. The default value is 100. This option can only be set at server start or in the postgresql.conf file.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+In each round, no more than this percentage of the currently dirty buffers will be written (rounding up any fraction to the next whole number of buffers). The default value is 1. This option can only be set at server start or in the postgresql.conf file.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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 16.4.3 for information.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-This parameter is normally true. When set 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.
+This parameter is normally true. When set to false, it disables validation of the function body string during CREATE FUNCTION. Disabling validation is occasionally useful to avoid problems such as forward references when restoring function definitions from a dump.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Write a message to the server logs if checkpoints caused by the filling of checkpoint segment files happens more frequently than this number of seconds. The default is 30 seconds. Zero turns off the warning.
+Write a message to the server log 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 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 server process has written its commit record. The default is zero (no delay).
+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).

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Specifies the main server configuration file (customarily called postgresql.conf). This option can only be set on the postmaster command line.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Sets the query 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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Sets the query 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.
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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 PostgreSQL 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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Specifies the directory to use for data storage. This option can only be set at server start.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 (accomplished by the configure option --enable-cassert). Note that DEBUG_ASSERTIONS defaults to on if PostgreSQL has been built with assertions enabled.
+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 (accomplished by the configure option --enable-cassert). Note that debug_assertions defaults to on if PostgreSQL has been built with assertions enabled.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 output to the client or server logs. These options are off by default.
+These options enable various debugging output to be emitted. 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 actually send this output to the client or the server log, respectively. These options are off by default.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 output to the client or server logs. These options are off by default.
+These options enable various debugging output to be emitted. 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 actually send this output to the client or the server log, respectively. These options are off by default.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 output to the client or server logs. These options are off by default.
+These options enable various debugging output to be emitted. 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 actually send this output to the client or the server log, respectively. These options are off by default.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 output to the client or server logs. These options are off by default.
+These options enable various debugging output to be emitted. 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 actually send this output to the client or the server log, respectively. These options are off by default.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Number of seconds between buffer freelist reports. If set greater than zero, emit freelist statistics to the log every so many seconds. Zero (the default) disables reporting.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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 PostgreSQL query planner, refer to Section 13.2.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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, PostgreSQL will automatically use the default tablespace of the current database. For more information on tablespaces, see Section 18.6.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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". Consult Chapter 12 and SET TRANSACTION for more information.
+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 Chapter 12 and SET TRANSACTION for more information.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+This controls whether CREATE TABLE and CREATE TABLE AS include an OID column in newly-created tables, if neither WITH OIDS nor WITHOUT OIDS is specified. It also determines whether OIDs will be included in tables created by SELECT INTO. In PostgreSQL 8.0.26 default_with_oids defaults to true. This is also the behavior of previous versions of PostgreSQL. However, assuming that tables will contain OIDs by default is not encouraged. This option will probably default to false in a future release of PostgreSQL. To ease compatibility with applications that make use of OIDs, this option should left enabled. To ease compatibility with future versions of PostgreSQL, this option should be disabled, and applications that require OIDs on certain tables should explicitly specify WITH OIDS when those tables are created.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-If a dynamically loadable module needs to be opened and 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 LOAD command.) The value for dynamic_library_path has to be a colon-separated list of absolute directory names. If a directory name starts with the special value $libdir, the compiled-in PostgreSQL package library directory is substituted. This where the modules provided by the PostgreSQL distribution are installed. (Use pg_config --pkglibdir to print the name of this directory.) For example: dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' 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.
+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 PostgreSQL package library directory is substituted for $libdir. This is where the modules provided by the standard PostgreSQL distribution are installed. (Use pg_config --pkglibdir to find out the name of this directory.) For example: dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir' or, in a Windows environment: dynamic_library_path = 'C:\tools\postgresql;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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Sets the planner'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 8192 bytes each. The default is 1000.
+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 PostgreSQL's shared buffers and the portion of the kernel's disk cache that will be used for PostgreSQL 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 PostgreSQL, 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+Enables or disables the query planner's use of hashed aggregation plan types. The default is on.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+Enables or disables the query planner's use of hash-join plan types. The default is on.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+Enables or disables the query planner's use of index-scan plan types. The default is on.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+Enables or disables the query planner's use of merge-join plan types. The default is on.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+Enables or disables the query planner's use of TID scan plan types. The default is on.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Specifies the name of an additional process-id (PID) file that the postmaster should create for use by server administration programs. This option can only be set at server start.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-If this option is on, the PostgreSQL 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. (Crashes of the database server itself are not related to this.) However, using fsync() results in a performance penalty: when a transaction is committed, PostgreSQL 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. 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.
+If this option is on, the PostgreSQL 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, PostgreSQL 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Enables or disables genetic query optimization, which is an algorithm that attempts to do query planning without exhaustive searching. This is on by default. See also the various other geqo_ settings.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+Controls the trade off 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 likelihood 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 11. 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.
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Specifies the configuration file for host-based authentication (customarily called pg_hba.conf). This option can only be set at server start.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Specifies the configuration file for ident authentication (customarily called pg_ident.conf). This option can only be set at server start.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Shows whether PostgreSQL was built with support for 64-bit-integer dates and times. It is set by configuring with --enable-integer-datetimes when building PostgreSQL. The default value is off.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-The planner will flatten explicit inner JOIN constructs into lists of FROM items whenever a list of no more than this many items would result. Usually this is set the same as from_collapse_limit. Setting it to 1 prevents any flattening of inner JOINs, allowing explicit JOIN syntax to be used to control the join order. Intermediate values might be useful to trade off planning time against quality of plan.
+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. Prior to PostgreSQL 7.4, joins specified via the JOIN construct would never be reordered by the query planner. The query planner has subsequently been improved so that inner joins written in this form can be reordered; 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 PostgreSQL. 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. Another consequence of setting this variable to 1 is that the query planner will behave more like the PostgreSQL 7.3 query planner, which some users might find useful for backward compatibility reasons. 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).

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Shows the locale in which sorting of textual data is done. See Section 20.1 for more information. The value is determined when the database cluster is initialized.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Shows the locale that determines character classifications. See Section 20.1 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Sets the locale to use for formatting numbers, for example with the to_char() family of functions. Acceptable values are system-dependent; see Section 20.1 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.
+Sets the locale to use for formatting numbers, for example with the to_char family of functions. Acceptable values are system-dependent; see Section 20.1 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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+This outputs a line to the server log 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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+PostgreSQL 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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+This outputs a line in the server log 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Causes the duration of every completed statement to be logged. To use this option, enable log_statement and log_pid so you can link the statement to the duration using the process ID. The default is off. Only superusers can turn off this option if it is enabled by the administrator.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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. Only superusers can change this setting.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-For each query, write performance statistics of the respective module to the server log. This is a crude profiling instrument. All of these options are disabled by default. Only superusers can turn off any of these options if they have been enabled by the administrator.
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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, PostgreSQL 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+By default, connection log messages only show the IP address of the connecting host. Turning on this option causes logging of the host name as well. Note that depending on your host name resolution setup this might impose a non-negligible performance penalty. This option can only be set at server start or in the postgresql.conf file.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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 postmaster. Syslog produces its own time stamp 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. Escape Effect Session only %u User name yes %d Database name yes %r Remote host name or IP address, and remote port yes %p Process ID no %t Time stamp no %i Command tag: This is the command that generated the log line. yes %c Session ID: A unique identifier for each session. It is 2 4-byte hexadecimal numbers (without leading zeros) separated by a dot. The numbers are the session start time and the process ID, so this can also be used as a space saving way of printing these items. yes %l Number of the log line for each process, starting at 1 no %s Session start time stamp yes %x Transaction ID yes %q Does not produce any output, but tells non-session processes to stop at this point in the string. Ignored by session processes. no %% Literal % no

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Sets a minimum statement execution time (in milliseconds) for statement to be logged. All SQL statements that run in 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 this. 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 increase this or set it to minus-one if this option is set by the administrator.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 a higher level, 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 increase this option.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 increase this option.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-For each query, write performance statistics of the respective module to the server log. This is a crude profiling instrument. All of these options are disabled by default. Only superusers can turn off any of these options if they have been enabled by the administrator.
+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.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-Prefixes each message in the server log file with the process ID of the server process. This is useful to sort out which messages pertain to which connection. The default is off. This parameter does not affect messages logged via syslog, which always contain the process ID.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-For each query, write performance statistics of the respective module to the server log. This is a crude profiling instrument. All of these options are disabled by default. Only superusers can turn off any of these options if they have been enabled by the administrator.
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-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 option can only be set at server start.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Causes each SQL statement to be logged. The default is off. Only superusers can turn off this option if it is enabled by the administrator.
+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 PL/pgSQLserver-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 PL/pgSQL keeps a cache of the query plans produced for the SQL statements in the function.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-For each query, write performance statistics of the respective module to the server log. This is a crude profiling instrument. All of these options are disabled by default. Only superusers can turn off any of these options if they have been enabled by the administrator.
+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.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-Prefixes each server log message with a time stamp. The default is off.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+When redirect_stderr is enabled, this option will cause PostgreSQL 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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 PostgreSQL to request more System V shared memory or semaphores than your operating system's default configuration allows. See Section 16.5.1 for information on how to adjust these parameters, if necessary.
+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 PostgreSQL to request more System V shared memory or semaphores than your operating system's default configuration allows. See Section 16.5.1 for information on how to adjust those parameters, if necessary.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-Sets the maximum expression nesting depth of the parser. The default value of 10000 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 server crashes due to stack overflow.)

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 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. (Thus, this parameter's name may be confusing: it is not a hard limit on the number of locks taken by any one transaction, but rather a maximum average value.) 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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-The TCP port the server listens on; 5432 by default. This option can only be set at server start.
+The TCP port the server listens on; 5432 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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 '$libdir/mylib:mylib_init' would cause mylib to be preloaded and mylib_init to be executed. If more than one library is to be loaded, separate their names with commas. If mylib or mylib_init are not found, the server will fail to start. PostgreSQL procedural language libraries may be preloaded in this way, typically by using the syntax '$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.
+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 '$libdir/mylib:mylib_init' would cause mylib to be preloaded and mylib_init to be executed. If more than one library is to be loaded, separate their names with commas. If a specified library or initialization function is not found, the server will fail to start. PostgreSQL procedural language libraries may be preloaded in this way, typically by using the syntax '$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 slightly, even if that process never uses the library. So this option is recommended only for libraries that will be used in most sessions.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Sets the query 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.
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-The regular expression "flavor" can be set to advanced, extended, or basic. The default is advanced. The extended setting may be useful for exact backwards compatibility with pre-7.4 releases of PostgreSQL.
+The regular expression "flavor" can be set to advanced, extended, or basic. The default is advanced. The extended setting may be useful for exact backwards compatibility with pre-7.4 releases of PostgreSQL. See Section 9.7.3.1 for details.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Specifies the Rendezvous broadcast name. By default, the computer name is used, specified as ''.
+Specifies the Rendezvous broadcast name. By default, the computer name is used, specified as an empty string ''. This option is ignored if the server was not compiled with Rendezvous support. This option can only be set at server start.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+Shows the version number of the server. It is determined by the value of PG_VERSION when building the server.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 PostgreSQL to request more System V shared memory than your operating system's default configuration allows. See Section 16.5.1 for information on how to adjust these parameters, if necessary.
+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 PostgreSQL to request more System V shared memory than your operating system's default configuration allows. See Section 16.5.1 for information on how to adjust those parameters, if necessary.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Runs the server silently. If this option is set, the server will automatically run in background and any controlling terminals are disassociated. Thus, no messages are written to standard output or standard error (same effect as postmaster's -S option). Unless syslog logging is enabled, using this option is discouraged since it makes it impossible to see error messages.
+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 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.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-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 sort operations simultaneously. So the total memory used could be many times the value of sort_mem. Sort operations are used by ORDER BY, merge joins, and CREATE INDEX. Hash tables are used in hash joins, hash-based aggregation, and hash-based processing of IN subqueries. Because CREATE INDEX is used when restoring a database, increasing sort_mem before doing a large restore operation can improve performance.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Enables SSL connections. Please read Section 16.7 before using this. The default is off.
+Enables SSL connections. Please read Section 16.8 before using this. The default is off. This parameter can only be set at server start.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Aborts any statement that takes over the specified number of milliseconds. A value of zero turns off the timer, which is the default value.
+Abort any statement that takes over the specified number of milliseconds. A value of zero (the default) turns off the limitation.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-These enable the collection of block-level and row-level statistics on database activity, respectively. These options are off by default. This data can be accessed via the pg_stat and pg_statio family of system views; refer to Chapter 23 for more information.
+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 23 for more information.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-These enable the collection of block-level and row-level statistics on database activity, respectively. These options are off by default. This data can be accessed via the pg_stat and pg_statio family of system views; refer to Chapter 23 for more information.
+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 23 for more information.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Determines the number of "connection slots" that are reserved for connections by PostgreSQL superusers. At most max_connections connections can ever be active simultaneously. Whenever the number of active concurrent connections is at least max_connections minus superuser_reserved_connections, new connections will be accepted only for superusers. The default value is 2. The value must be less than the value of max_connections. This parameter can only be set at server start.
+Determines the number of connection "slots" that are reserved for connections by PostgreSQL superusers. At most max_connections connections can ever be active simultaneously. Whenever the number of active concurrent connections is at least max_connections minus superuser_reserved_connections, new connections will be accepted only for superusers. The default value is 2. The value must be less than the value of max_connections. This parameter can only be set at server start.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-This option determines the syslog "facility" to be used when logging via 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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+When logging to syslog is enabled, this option determines the program name used to identify PostgreSQL messages in syslog logs. The default is postgres. This option can only be set at server start.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-When turned on, expressions of the form 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 expr = NULL is to always return null (unknown). Therefore this option defaults to off. However, filtered forms in Microsoft Access generate queries that appear to use expr = NULL to test for null values, so if you use that interface to access the database you might want to turn this option on. Since expressions of the form expr = NULL always return the null value (using the correct interpretation) they are not 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 values, so this option is not on by default. Note that this option only affects the literal = operator, not other comparison operators or other expressions that are computationally equivalent to some expression involving the equals operator (such as IN). Thus, this option is not a general fix for bad programming. Refer to Section 9.2 for related information.
+When turned on, expressions of the form 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 SQL-spec-compliant behavior of expr = NULL is to always return null (unknown). Therefore this option defaults to off. However, filtered forms in Microsoft Access generate queries that appear to use expr = NULL to test for null values, so if you use that interface to access the database you might want to turn this option on. Since expressions of the form expr = NULL always return the null value (using the correct interpretation) they are not 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 values, so this option is not on by default. Note that this option only affects the exact form = NULL, not other comparison operators or other expressions that are computationally equivalent to some expression involving the equals operator (such as IN). Thus, this option is not a general fix for bad programming. Refer to Section 9.2 for related information.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Sets the group owner 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 this socket type. 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.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-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 an 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 under 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 19. This option can only be set at server start.
+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 for a Unix-domain socket, only write permission matters and so there is no point in setting or revoking read or execute permissions.) This access control mechanism is independent of the one described in Chapter 19. This option can only be set at server start.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+The accumulated cost that will cause the vacuuming process to sleep. The default value is 200.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-Specifies the maximum amount of memory to be used by VACUUM to keep track of to-be-reclaimed rows. The value is specified in kilobytes, and defaults to 8192 kB. Larger settings may improve the speed of vacuuming large tables that have many deleted rows.

--- 7.4
+++ 8.0
@@ -1,3 +0,0 @@
-
-
-Specifies the host name or IP address on which the server is to listen for connections from client applications. The default is to listen on all configured addresses (including localhost).

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Number of disk-page buffers in shared memory for WAL logging. The default is 8. This option can only be set at server start.
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-If nonzero, turn on WAL-related debugging output.
+If true, emit WAL-related debugging output. This option is only available if the WAL_DEBUG macro was defined when PostgreSQL was compiled.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Method used for forcing WAL updates out to disk. Possible values are fsync (call fsync() at each commit), fdatasync (call fdatasync() at each commit), open_sync (write WAL files with open() option O_SYNC), and open_datasync (write WAL files with open() option O_DSYNC). Not all of these choices are available on all platforms. This option can only be set at server start or in the postgresql.conf file.
+Method used for forcing WAL updates out to disk. Possible values are fsync (call fsync() at each commit), fdatasync (call fdatasync() at each commit), fsync_writethrough (call _commit() at each commit on Windows), open_sync (write WAL files with open() option O_SYNC), and open_datasync (write WAL files with open() option O_DSYNC). 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.

--- 7.4
+++ 8.0
@@ -0,0 +1,3 @@
+
+
+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.

--- 7.4
+++ 8.0
@@ -1 +1 @@
-Detection of a damaged page header normally causes PostgreSQL to report an error, aborting the current transaction. Setting zero_damaged_pages to true causes the system to instead report a warning, zero out the damaged page, and continue processing. This behavior will destroy data, namely all the rows on the damaged page. But it allows you to get past the error and retrieve rows from any undamaged pages that may be present in the table. So it is useful for recovering data if corruption has occurred due to hardware or software error. You should generally not set this true until you have given up hope of recovering data from the damaged page(s) of a table. The default setting is off, and it can only be changed by a superuser.
+Detection of a damaged page header normally causes PostgreSQL to report an error, aborting the current command. Setting zero_damaged_pages to true causes the system to instead report a warning, zero out the damaged page, and continue processing. This behavior will destroy data, namely all the rows on the damaged page. But it allows you to get past the error and retrieve rows from any undamaged pages that may be present in the table. So it is useful for recovering data if corruption has occurred due to hardware or software error. You should generally not set this true until you have given up hope of recovering data from the damaged page(s) of a table. The default setting is off, and it can only be changed by a superuser.