\&.../src/backend/obj/{local,dbdb}.bki\(em template scripts

*.bki

Backend Interface (BKI) files are scripts that describe the contents

of the initial Postgres database. This database is constructed during

system installation, by the

.IR initdb

command.

.IR Initdb

executes the Postgres backend with a special set of flags, that cause it

to consume the BKI scripts and bootstrap a database.

Backend Interface (BKI) files are scripts that are input to the postgres

backend running in the special "bootstrap" mode that allows it to perform

database functions without a database system already existing. BKI files

can therefore be used to create the database system in the first place.

.PP

These files are automatically generated from system header files

during installation. They are not intended for use by humans, and you

do not need to understand their contents in order to use Postgres. These

files are copied to

.nf

\&.../files/{global1,local1_XXX}.bki

.fi

during system installation.

.PP

All new user databases will be created by copying the template

database that Postgres constructs from the BKI files. Thus, a simple way

to customize the template database is to let the Postgres initialization

script create it for you, and then to run the terminal monitor to make

the changes you want.

.IR Initdb

uses BKI files to do just that -- create a database system. However,

.IR initdb's

BKI files are generated internally. It generates them using the files

global1.bki.source and local1.template1.bki.source, which it finds in the

Postgres "library" directory. They get installed there as part of installing

Postgres. These .source files get build as part of the Postgres build

process, by a build program called

.IR genbki.Genbki

takes as input Postgres source files that double as

.IR genbki

input that builds tables and C header files that describe those

tables.

.PP

The Postgres backend interprets BKI files as described below. This

description will be easier to understand if the example in

\*(lq.../files/global1.bki\*(rq is at hand.

description will be easier to understand if the global1.bki.source file is

at hand as an example. (As explained above, this .source file isn't quite

a BKI file, but you'll be able to guess what the resulting BKI file would be

anyway).

.PP

Commands are composed of a command name followed by space separated

arguments. Arguments to a command which begin with a\*(lq$\*(rq are

initdb(1),

createdb(1),

createdb(l),

template(files).

create_database(l).

$PGDATA/pg_hba.conf

"Host-based access control" is the name for the basic controls Postgres

exercises on what clients are allowed to access a database system.

It is called that because one of the factors that can control access is

from what host the client is connecting.

.PP

Each database system contains a file named "pg_hba.conf", in its PGDATA

directory, that controls who can connect to that database system.

.PP

The exact format of the pg_hba.conf file is described in the comments at

the top of the sample file pg_hba.conf.sample, which resides in the

Postgres "library" directory.

introduction(1).