I find [SQLTap](http://sqltap.inconshreveable.com/) invaluable for
profiling SQLAlchemy queries. Currently, I've reduced one operation in our
system from nearly 12,000 queries to 800, and I'm not finished yet.
SQLTap listens for the before_execute and after_execute events. In
after_execute, it captures the query time, the text of the query, and the
parameters. These are aggregated into a profiling report.
For some queries, it fails to capture the actual parameter(s), instead
reporting param_1 as None. The queries work, of course, and do have a
non-None parameter. Typically these queries boil down to
query(class).get(id).
Here's what the after_execute listener in SQLTap looks like (simplified):
def _after_execute(self, conn, clause, multiparams, params, results):
duration = time.time() - conn._sqltap_query_start_time
try:
text = clause.compile(dialect=conn.engine.dialect)
except AttributeError:
text = clause
query_params = getattr(text, 'params', {})
I've set a breakpoint in _after_execute and examined the multiparams and
params arguments. The results typically look like
multiparams ({'%(4480418320 param)s': 37},)
params {}
query_params {u'param_1': None}
I've put some sample code up at
https://gist.github.com/georgevreilly/11f87d1d2f4664206df2
I'm using SQLAlchemy 0.9.9.
Is there a reliable way of capturing the actual query parameters?
--
/George V. Reilly [email protected] Twitter: @georgevreilly
<https://twitter.com/georgevreilly>
*www.GeorgeVReilly.com <http://www.GeorgeVReilly.com>*
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