http://www.tcl.tk/community/tcl2007/proceedings/databases/speedtables-paper-2.pdf
Speed tables provides an interface for defining tables containing zero or more rows, with each row containing one or more fields. The speed table compiler reads a table definition (similar to a C struct definition) and generates C code to create and manage tables where the rows are such structures, producing a set of C access routines and a C language extension for Tcl to create, access and manipulate those tables. It then compiles the extension, links it as a shared library, and makes it loadable on demand via Tcl's "package require" mechanism.
Speed tables are well-suited for applications for which this table/row/field abstraction is useful, with row counts from the dozens to the tens of millions, for which the performance requirements for access, search and/or update frequency exceed those of the available SQL database, and the application does not require “no transaction loss” behavior in the event of a crash.
Project link: http://sourceforge.net/projects/speedtables