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: to 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. Related information may be found in documentation for initdb, createdb, and the SQL command CREATE DATABASE. 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 "$" are treated specially. If "$$" are the first two characters, then the first "$" is ignored and the argument is then processed normally. If the "$" is followed by space, then it is treated as a NULL value. Otherwise, the characters following the "$" 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. 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 zero (0), 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 indexname ON class_name USING amname (opclass attr | (function(attr)) Create an index named indexname 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. This last sentence doesn't reference anything in the example. Should be changed to make sense. - Thomas 1998-08-04 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 macro_name which has its value read from the file called filename. This section on debugging commands was commented-out in the original documentation. Thomas 1998-08-05 r Randomly print the open class. m -1 Toggle display of time information. m 0 Set retrievals to now. m 1 Jan 1 01:00:00 1988 Set retrievals to snapshots of the specfied time. m 2 Jan 1 01:00:00 1988, Feb 1 01:00:00 1988 Set retrievals to ranges of the specified times. Either time may be replaced with space if an unbounded time range is desired. &A classname natts name1 type1 name2 type2 ... Add natts attributes named name1, name2, etc. of types type1, type2, etc. to the class classname. &RR oldclassname newclassname Rename the oldclassname class to newclassname. &RA classname oldattname newattname classname oldattname newattname Rename the oldattname attribute in the class named classname to newattname. The following set of commands will create the pg_opclass class containing the int_ops collection as an object with an OID of 421, print out the class, and then close it. create pg_opclass (opcname=name) open pg_opclass insert oid=421 (int_ops) print close pg_opclass