Hey Jim, 2012/8/8 Jim Vanns <james.va...@framestore.com>
> Hello PG hackers. Yesterday I began diagnosing a peculiar bug in some > production code that has been happily running for months. I finally got > to the bottom of it despite the rather misleading error message. Anyway, > within a section of code we are making a DELETE call to the database via > the libpq call PQexecParams(). It failed with this message: > > 'ERROR: bind message has 32015 parameter formats but 1 parameters' > > This was just plain wrong. In fact, the # of parameters was more like > 80,000. The area of code is quite clear. Despite this being a > particularly large number of parameters (as you can imagine this query > is built dynamically based on arbitrarily sized input) the data type for > nParams for is a plain old 4-byte int. Upon further and deeper > inspection I find that this 4 byte int is truncated to two bytes just > before going down the wire. > > There is no mention of any restriction in the 9.1.4 documentation: > > http://www.postgresql.org/docs/9.1/static/libpq-exec.html > > And the interface quite clearly accepts a 4 byte int however, the > PQsendQueryGuts() > function on line 1240 of src/interfaces/libpq/fq-exec.c just blatantly > truncates the > integer - it's calls pqPutInt() for nParams with a literal 2 rather than > 4. It does this > several times, in fact. > > Unless I'm barking mad, surely this should either > > a) Be fixed and send 4 with nParams for pqPutInt() rather than 2 > b) Documented (and the type changed) as only being a 2 byte int > and therefore having a restriction on the number of parameters > permitted in PQexecParams(). > > Could someone either verify or correct me before I submit an official bug > report!? > > Regards, > > Jim Vanns > AFAIK, this is a limitation of the frontend/backend protocol which allows you to bind no more than 2^16 parameters. See the description of the Bind (F) message here http://www.postgresql.org/docs/9.2/static/protocol-message-formats.html -- // Dmitriy.
