[Libpqxx-general] cancellation of synchronous sql statements

[Madden, Don (DCOR)]

Hi ,

 

If you execute commands (asynchronously) in a "pipeline", there is a
public method to "cancel()" an ongoing query.

 

 If you execute the SQL commands in a blocking call, you could the
cancel the ongoing command via a signal handler (e.g SIGALRM). lIbpq
supports this via PQcancel(). "libpqxx" doesn't seem to have any
equivalent public method. In the connection_base, the wrapper method,
"cancel_query()" is private.  Likewise I couldn't find any public method
to get a raw libpq connection, PGConn in libpqxx's connection_base
classes?

 

Is there some other way to cancel blocking queries via libpqxx, instead
of using pipelines, e.g a timeout associated with a transaction or the
sql statement? I am limited from using pipelines as I plan to use
cursors through the "stateless_cursor" class whose retrieve() method
executes blocking SQL commands. As a result, I cannot find a way to
cancel a stateless cursor retrieve that may take too long.

 

Thanks,

Don



 
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