Thank you to all!
It is what I'm looking for!

> A flat file database that has been around a long time is Berkeley
> database. You can select between a C\C++ or Java driven database. For
> years it was the product of Sleepycat but Big Brother owns it now at Oracle.
>
> http://www.oracle.com/database/berkeley-db/index.html
>
> Another one that that is newer is a C based DB called SQLite.
> http://pecl.php.net/package/SQLite
>
> You will not have any problems searching these database because they
> support SQL.