On Wed, 29 Apr 2009 00:05:33 +0200 Markus Hoenicka <markus.hoeni...@mhoenicka.de> wrote:
> Hi Chuck, > > Chuck Hemker writes: > > When you get a lock timeout on a select, it is reported by mysql by > returning > > a null from mysql_store_result. This currently isn't noticed by the > driver. > > > > In dbd_query (and dbd_query_null) in dbd_mysql.c there should be 3 cases: > > > > mysql_store_result() != null good select > > mysql_store_result() = null & mysql_field_count() = 0 good insert ... > > mysql_store_result() = null & mysql_field_count() > 0 error on select > > > > thanks for reporting this problem and for suggesting a fix. Is this > MySQL behaviour documented somewhere, or did you just observe this? Is > your fix supposed to work with all MySQL releases since, say, 4.0? If > both answers are yes, your suggested fix is likely to make its way > into the driver. I haven't used the mysql api that much because I like libdbi. :) However, take a look a these pages that I found with a little bit of digging: In the mysql 5.0 manual: http://dev.mysql.com/doc/refman/5.0/en/null-mysql-store-result.html Why mysql_store_result() Sometimes Returns NULL After mysql_query() Returns Success ... You can always check whether the statement should have produced a non-empty result by calling mysql_field_count(). --- http://dev.mysql.com/doc/refman/5.0/en/mysql-field-count.html The normal use of this function is when mysql_store_result() returned NULL (and thus you have no result set pointer). In this case, you can call mysql_field_count() to determine whether mysql_store_result() should have produced a non-empty result. This allows the client program to take proper action without knowing whether the query was a SELECT (or SELECT-like) statement. Also has a bit of example code. --- These seem to be similar pages in the 3.23/4.0/4.1 manual: http://dev.mysql.com/doc/refman/4.1/en/null-mysql-store-result.html http://dev.mysql.com/doc/refman/4.1/en/mysql-field-count.html This one says: If you are using a version of MySQL earlier than 3.22.24, you should use unsigned int mysql_num_fields(MYSQL *mysql) instead. --- So it looks like it should work with mysql 3.22.24 or later. ------------------------------------------------------------------------------ Register Now & Save for Velocity, the Web Performance & Operations Conference from O'Reilly Media. Velocity features a full day of expert-led, hands-on workshops and two days of sessions from industry leaders in dedicated Performance & Operations tracks. Use code vel09scf and Save an extra 15% before 5/3. http://p.sf.net/sfu/velocityconf _______________________________________________ Libdbi-drivers-devel mailing list Libdbi-drivers-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libdbi-drivers-devel
