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From André Cruz <andre.c...@co.sapo.pt>
Subject Re: Strange delay in query
Date Thu, 08 Nov 2012 12:01:23 GMT
On Nov 7, 2012, at 12:15 PM, André Cruz <andre.cruz@co.sapo.pt> wrote:

> This error also happens on my application that uses pycassa, so I don't think this is
the same bug.

I have narrowed it down to a slice between two consecutive columns. Observe this behaviour
using pycassa:

>>> DISCO_CASS.col_fam_nsrev.get(uuid.UUID('3cd88d97-ffde-44ca-8ae9-5336caaebc4e'),
column_count=2, column_start=uuid.UUID('13957152-234b-11e2-92bc-e0db550199f4')).keys()
DEBUG 2012-11-08 11:55:51,170 pycassa_library.pool:30 6849 139928791262976 Connection 52905488
(xxx:9160) was checked out from pool 51715344
DEBUG 2012-11-08 11:55:53,415 pycassa_library.pool:37 6849 139928791262976 Connection 52905488
(xxx:9160) was checked in to pool 51715344
[UUID('13957152-234b-11e2-92bc-e0db550199f4'), UUID('40b7ae4e-2449-11e2-8610-e0db550199f4')]

A two column slice took more than 2s to return. If I request the next 2 column slice:

>>> DISCO_CASS.col_fam_nsrev.get(uuid.UUID('3cd88d97-ffde-44ca-8ae9-5336caaebc4e'),
column_count=2, column_start=uuid.UUID('40b7ae4e-2449-11e2-8610-e0db550199f4')).keys()
DEBUG 2012-11-08 11:57:32,750 pycassa_library.pool:30 6849 139928791262976 Connection 52904912
(xxx:9160) was checked out from pool 51715344
DEBUG 2012-11-08 11:57:32,774 pycassa_library.pool:37 6849 139928791262976 Connection 52904912
(xxx:9160) was checked in to pool 51715344
[UUID('40b7ae4e-2449-11e2-8610-e0db550199f4'), UUID('a364b028-2449-11e2-8882-e0db550199f4')]

This takes 20msec... Is there a rational explanation for this different behaviour? Is there
some threshold that I'm running into? Is there any way to obtain more debugging information
about this problem?

Thanks,
André
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