The following “parameters” are read-only.
As such, they have been excluded from the sample
postgresql.conf file. These options report
various aspects of PostgreSQL behavior
that might be of interest to certain applications, particularly
administrative front-ends.
Most of them are determined when PostgreSQL
is compiled or when it is installed.
block_size (integer)
#
Reports 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 19.4 for information.
data_checksums (boolean)
#Reports whether data checksums are enabled for this cluster. See data checksums for more information.
data_encryption (boolean)
#Reports whether data encryption is enabled for this cluster. See Chapter 31 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 PostgreSQL has been built
with assertions enabled. That is the case if the
macro USE_ASSERT_CHECKING is defined
when PostgreSQL is built (accomplished
e.g., by the configure option
--enable-cassert). By
default PostgreSQL is built without
assertions.
huge_pages_status (enum)
#
Reports the state of huge pages in the current instance:
on, off, or
unknown (if displayed with
postgres -C).
This parameter is useful to determine whether allocation of huge pages
was successful under huge_pages=try.
See huge_pages for more information.
integer_datetimes (boolean)
#
Reports whether PostgreSQL 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 26.4 for more
information.
max_function_args (integer)
#
Reports the maximum number of function arguments. It is determined by
the value of FUNC_MAX_ARGS when 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 NAMEDATALEN when building
the server. The default value of NAMEDATALEN is
64; therefore the default
max_identifier_length is 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_KEYS when 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_SIZE
when building the server. The maximum size of a segment file in bytes
is equal to segment_size multiplied by
block_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_VERSION when 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_NUM when 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 -1 on other platforms. For more
details about using huge pages on Linux, see
Section 18.4.5.
ssl_library (string)
#
Reports the name of the SSL library that this
PostgreSQL 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_BLCKSZ when 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.