18.15. Preset Options#
18.15. Preset Options #
The following “parameters” are read-only.
As such, they have been excluded from the sample
postgresql.conf file. These options report
various aspects of Tantor SE-1C behavior
that might be of interest to certain applications, particularly
administrative front-ends.
Most of them are determined when Tantor SE-1C
is compiled or when it is installed.
block_size(integer) #Reports the size of a disk block. It is determined by the value of
BLCKSZwhen building the server. The default value is 8192 bytes. The meaning of some configuration variables (such as shared_buffers) is influenced byblock_size. See Section 18.4 for information.data_checksums(boolean) #Reports whether data checksums are enabled for this cluster. See data checksums for more information.
data_directory_mode(integer) #On Unix systems this parameter reports the permissions the data directory (defined by data_directory) had at server startup. (On Microsoft Windows this parameter will always display
0700.) See group access for more information.debug_assertions(boolean) #Reports whether Tantor SE-1C has been built with assertions enabled. That is the case if the macro
USE_ASSERT_CHECKINGis defined when Tantor SE-1C is built (accomplished e.g., by theconfigureoption--enable-cassert). By default Tantor SE-1C is built without assertions.integer_datetimes(boolean) #Reports whether Tantor SE-1C was built with support for 64-bit-integer dates and times. As of PostgreSQL 10, this is always
on.in_hot_standby(boolean) #Reports whether the server is currently in hot standby mode. When this is
on, all transactions are forced to be read-only. Within a session, this can change only if the server is promoted to be primary. See Section 25.4 for more information.max_function_args(integer) #Reports the maximum number of function arguments. It is determined by the value of
FUNC_MAX_ARGSwhen building the server. The default value is 100 arguments.max_identifier_length(integer) #Reports the maximum identifier length. It is determined as one less than the value of
NAMEDATALENwhen building the server. The default value ofNAMEDATALENis 64; therefore the defaultmax_identifier_lengthis 63 bytes, which can be less than 63 characters when using multibyte encodings.max_index_keys(integer) #Reports the maximum number of index keys. It is determined by the value of
INDEX_MAX_KEYSwhen building the server. The default value is 32 keys.segment_size(integer) #Reports the number of blocks (pages) that can be stored within a file segment. It is determined by the value of
RELSEG_SIZEwhen building the server. The maximum size of a segment file in bytes is equal tosegment_sizemultiplied byblock_size; by default this is 1GB.server_encoding(string) #Reports the database encoding (character set). It is determined when the database is created. Ordinarily, clients need only be concerned with the value of client_encoding.
server_version(string) #Reports the version number of the server. It is determined by the value of
PG_VERSIONwhen building the server.server_version_num(integer) #Reports the version number of the server as an integer. It is determined by the value of
PG_VERSION_NUMwhen building the server.shared_memory_size(integer) #Reports the size of the main shared memory area, rounded up to the nearest megabyte.
shared_memory_size_in_huge_pages(integer) #Reports the number of huge pages that are needed for the main shared memory area based on the specified huge_page_size. If huge pages are not supported, this will be
-1.This setting is supported only on Linux. It is always set to
-1on other platforms. For more details about using huge pages on Linux, see Section 17.4.5.ssl_library(string) #Reports the name of the SSL library that this Tantor SE-1C server was built with (even if SSL is not currently configured or in use on this instance), for example
OpenSSL, or an empty string if none.wal_block_size(integer) #Reports the size of a WAL disk block. It is determined by the value of
XLOG_BLCKSZwhen building the server. The default value is 8192 bytes.wal_segment_size(integer) #Reports the size of write ahead log segments. The default value is 16MB. See Section 28.5 for more information.