20.2. File Locations

20.2. File Locations
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+ In addition to the postgresql.conf file + already mentioned, PostgreSQL uses + two other manually-edited configuration files, which control + client authentication (their use is discussed in Chapter 21). By default, all three + configuration files are stored in the database cluster's data + directory. The parameters described in this section allow the + configuration files to be placed elsewhere. (Doing so can ease + administration. In particular it is often easier to ensure that + the configuration files are properly backed-up when they are + kept separate.) +

data_directory (string) + +: + Specifies the directory to use for data storage. + This parameter can only be set at server start. +
config_file (string) + +: + Specifies the main server configuration file + (customarily called postgresql.conf). + This parameter can only be set on the postgres command line. +
hba_file (string) + +: + Specifies the configuration file for host-based authentication + (customarily called pg_hba.conf). + This parameter can only be set at server start. +
ident_file (string) + +: + Specifies the configuration file for user name mapping + (customarily called pg_ident.conf). + This parameter can only be set at server start. + See also Section 21.2. +
external_pid_file (string) + +: + Specifies the name of an additional process-ID (PID) file that the + server should create for use by server administration programs. + This parameter can only be set at server start. +

+ In a default installation, none of the above parameters are set + explicitly. Instead, the + data directory is specified by the -D command-line + option or the PGDATA environment variable, and the + configuration files are all found within the data directory. +

+ If you wish to keep the configuration files elsewhere than the + data directory, the postgres -D + command-line option or PGDATA environment variable + must point to the directory containing the configuration files, + and the data_directory parameter must be set in + postgresql.conf (or on the command line) to show + where the data directory is actually located. Notice that + data_directory overrides -D and + PGDATA for the location + of the data directory, but not for the location of the configuration + files. +

+ If you wish, you can specify the configuration file names and locations + individually using the parameters config_file, + hba_file and/or ident_file. + config_file can only be specified on the + postgres command line, but the others can be + set within the main configuration file. If all three parameters plus + data_directory are explicitly set, then it is not necessary + to specify -D or PGDATA. +

+ When setting any of these parameters, a relative path will be interpreted + with respect to the directory in which postgres + is started. +

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