Usage instructions

Single-threaded vs multi-threaded operation

Users may execute PiCO_QL in the same thread as the application (single-threaded) or in a separate thread. In the former case, PiCO_QL has to be compiled with PICO_QL_SINGLE_THREADED flag enabled and pico_ql_serve() may be called from within a loop as in Quickstart if returning is a problem. In the latter case, a normal call to pico_ql_serve() is enough. When everything goes as planned pico_ql_serve() returns 1.

Using PiCO QL

In production (non-test) mode PICO QL opens port 8080 at localhost where the local server is listening for query requests. Opening a browser at this address reveals the query interface.

Updating virtual table definitions

Users may update table definitions in the DSL, execute the generator, re-compile and execute the application. One further action is required, to drop the previous virtual table definition from the database either by executing a standard

 DROP TABLE table_name;

from PiCO QL's web interface or by removing the database file, which lies in the directory where the application is run. When PiCO QL starts it will reinstate all missing virtual table definitions but will not overwrite existing definitions.