add support for deduplication on varstring column types

[bovine]

Boost supports a "flyweight" template that would allow easily implementation of deduplication of string values, which could provide a significant memory size reduction if values tend to be repeated a lot. (Basically allowing your tables to be denormalized but without the full storage overhead.)

http://www.boost.org/doc/libs/1_51_0/libs/flyweight/doc/tutorial/basics.html

The column could be defined as something like:
varstring filename notnull 1 default "" dedupe 1

[resuna]

Speedtables is not in C++, so this would be kind of tricky.

[bovine]

My new "cpp" branch of speedtables is C++ and uses boost :)

[resuna]

That sounds... exciting? Adventurous? :)

[apnadkarni]

Please please please keep C as an option if you move to C++. Deployment is much simpler, at least for binary distributions on Windows platforms.

As an aside, when working from Tcl, deduplication should be easy enough for the application by defining field as tclobj