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6.2.1 Base Table

A base-table is the primitive database layer upon which SLIB relational databases are built. At the minimum, it must support the types integer, symbol, string, and boolean. The base-table may restrict the size of integers, symbols, and strings it supports.

A base table implementation is available as the value of the identifier naming it (eg. alist-table) after requiring the symbol of that name.

— Feature: alist-table

(require 'alist-table) Association-list base tables support all Scheme types and are suitable for small databases. In order to be retrieved after being written to a file, the data stored should include only objects which are readable and writeable in the Scheme implementation.

The alist-table base-table implementation is included in the SLIB distribution.

WB is a B-tree database package with SCM interfaces. Being disk-based, WB databases readily store and access hundreds of megabytes of data. WB comes with two base-table embeddings.

— Feature: wb-table

(require 'wb-table) wb-table supports scheme expressions for keys and values whose text representations are less than 255 characters in length. See wb-table.

— Feature: rwb-isam

(require 'rwb-isam) rwb-isam is a sophisticated base-table implementation built on WB and SCM which uses binary numerical formats for key and non-key fields. It supports IEEE floating-point and fixed-precision integer keys with the correct numerical collation order.

This rest of this section documents the interface for a base table implementation from which the Relational Database package constructs a Relational system. It will be of interest primarily to those wishing to port or write new base-table implementations.

— Variable: *base-table-implementations*

To support automatic dispatch for open-database, each base-table module adds an association to *base-table-implementations* when loaded. This association is the list of the base-table symbol and the value returned by (make-relational-system base-table).