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[openstack-dev] [mistral] Pike limit of 100 results makes debugging much harder

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The Pike release of python-mistralclient added a default limit of 100
results returned to ease the burden on the database, which makes sense
because it's rare that anyone actually needs all of the results that are
returned.

Unfortunately with the default sort order of "asc" this means that only
the first 100 results are returned, so when debugging workflows and
running task-list, execution-list, and action-execution-list, the data
needed is not returned by default once there are more than 100
tasks/executions/action-executions in the database.

It's possible to work around this by specifying --limit assuming that the number you specify is greater than the number
of tuples in the database. The help text says that --limit -1 will
result in no limit but there is a bug [0] that results in an error from
the API instead. It's also possible to specify the execution id (when
listing tasks) or the task id (when listing action-executions) but this
adds additional steps to the process to find these IDs, when really all
you want is the last 100 results.

Even if the --limit -1 worked it's still not optimal to hit the database
that hard while debugging just so you can see the latest results of your
workflow/task/action executions.

Ideally the default would return the last 100 results, (limit = -100)
which is more likely to contain the information needed for debugging a
workflow.

We could add a --sort-dir option to the task/execution/action-execution
list commands to allow for descending sort order, which combined with
the default limit would return the last 100 results but in descending
order instead of ascending order, which means the latest results would
likely scroll off the screen. A second sort would be required to put
them in ascending order.

Is there a way to "retrieve the last results in ascending order"
from SQLAlchemy without doing a second sort in the client?

Thanks

Bob

[0] https://bugs.launchpad.net/python-mistralclient/+bug/1730755


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asked Nov 9, 2017 in openstack-dev by HADDLETON,_Robert_W_ (700 points)  
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