BKI (5)

DESCRIPTION

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.

Initdb uses BKI files to do just that -- create a database system. However, 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 genbki. Genbki takes as input Postgres source files that double as genbki input that builds tables and C header files that describe those tables.

The Postgres backend interprets BKI files as described below. This 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).

Commands are composed of a command name followed by space separated arguments. Arguments to a command which begin with a \*(lq$\*(rq are treated specially. If \*(lq$$\*(rq are the first two characters, then the first \*(lq$\*(rq is ignored and the argument is then processed normally. If the \*(lq$\*(rq is followed by space, then it is treated as a value. Otherwise, the characters following the \*(lq$\*(rq are interpreted as the name of a macro causing the argument to be replaced with the macro's value. It is an error for this macro to be undefined.

Macros are defined using

define macro macro_name = macro_value

and are undefined using

undefine macro macro_name

and redefined using the same syntax as define.

Lists of general commands and macro commands follow.

GENERAL COMMANDS

open classname

Open the class called classname for further manipulation.

close [classname]

Close the open class called classname. It is an error if classname is not already opened. If no classname is given, then the currently open class is closed.

print

Print the currently open class.

insert [oid=oid_value] ( value1 value2 ... )

Insert a new instance to the open class using value1 , value2 , etc., for its attribute values and oid_value for its OID. If oid_value is not \*(lq0\*(rq, then this value will be used as the instance's object identifier. Otherwise, it is an error.

insert ( value1 value2 ... )

As above, but the system generates a unique object identifier.

create classname ( name1 = type1, name2 = type2, ... )

Create a class named classname with the attributes given in parentheses.

open ( name1 = type1, name2 = type2,... ) as classname

Open a class named classname for writing but do not record its existence in the system catalogs. (This is primarily to aid in bootstrapping.)

destroy classname

Destroy the class named classname .

define index index-name on class-name using amname

( opclass attr | function({attr}) ) Create an index named index_name on the class named classname using the amname access method. The fields to index are called name1 , name2 , etc., and the operator collections to use are collection_1 , collection_2 , etc., respectively.

MACRO COMMANDS

define function macro_name as rettype function_name ( args )

Define a function prototype for a function named macro_name which has its value of type rettype computed from the execution function_name with the arguments args declared in a C-like manner.

define macro macro_name from file filename

Define a macro named macname which has its value read from the file called filename .