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From Josep Blanquer <blanq...@rightscale.com>
Subject Re: Strange delay in query
Date Thu, 08 Nov 2012 22:51:31 GMT
Can it be that you have tons and tons of tombstoned columns in the middle
of these two? I've seen plenty of performance issues with wide
rows littered with column tombstones (you could check with dumping the
sstables...)

Just a thought...

Josep M.

On Thu, Nov 8, 2012 at 12:23 PM, André Cruz <andre.cruz@co.sapo.pt> wrote:

> These are the two columns in question:
>
> => (super_column=13957152-234b-11e2-92bc-e0db550199f4,
>      (column=attributes, value=, timestamp=1351681613263657)
>      (column=blocks,
> value=A4edo5MhHvojv3Ihx_JkFMsF3ypthtBvAZkoRHsjulw06pez86OHch3K3OpmISnDjHODPoCf69bKcuAZSJj-4Q,
> timestamp=1351681613263657)
>      (column=hash,
> value=8_p2QaeRaX_QwJbUWQ07ZqlNHei7ixu0MHxgu9oennfYOGfyH6EsEe_LYO8V8EC_1NPL44Gx8B7UhYV9VSb7Lg,
> timestamp=1351681613263657)
>      (column=icon, value=image_jpg, timestamp=1351681613263657)
>      (column=is_deleted, value=true, timestamp=1351681613263657)
>      (column=is_dir, value=false, timestamp=1351681613263657)
>      (column=mime_type, value=image/jpeg, timestamp=1351681613263657)
>      (column=mtime, value=1351646803, timestamp=1351681613263657)
>      (column=name, value=/Mobile Photos/Photo 2012-10-28 17_13_50.jpeg,
> timestamp=1351681613263657)
>      (column=revision, value=13957152-234b-11e2-92bc-e0db550199f4,
> timestamp=1351681613263657)
>      (column=size, value=1379001, timestamp=1351681613263657)
>      (column=thumb_exists, value=true, timestamp=1351681613263657))
> => (super_column=40b7ae4e-2449-11e2-8610-e0db550199f4,
>      (column=attributes, value={"posix": 420}, timestamp=1351790781154800)
>      (column=blocks,
> value=9UCDkHNb8-8LuKr2bv9PjKcWCT0v7FCZa0ebNSflES4-o7QD6eYschVaweCKSbR29Dq2IeGl_Cu7BVnYJYphTQ,
> timestamp=1351790781154800)
>      (column=hash,
> value=kao2EV8jw_wN4EBoMkCXZWCwg3qQ0X6m9_X9JIGkEkiGKJE_JeKgkdoTAkAefXgGtyhChuhWPlWMxl_tX7VZUw,
> timestamp=1351790781154800)
>      (column=icon, value=text_txt, timestamp=1351790781154800)
>      (column=is_dir, value=false, timestamp=1351790781154800)
>      (column=mime_type, value=text/plain, timestamp=1351790781154800)
>      (column=mtime, value=1351378576, timestamp=1351790781154800)
>      (column=name, value=/Documents/VIMDocument.txt,
> timestamp=1351790781154800)
>      (column=revision, value=40b7ae4e-2449-11e2-8610-e0db550199f4,
> timestamp=1351790781154800)
>      (column=size, value=13, timestamp=1351790781154800)
>      (column=thumb_exists, value=false, timestamp=1351790781154800))
>
>
> I don't think their size is an issue here.
>
> André
>
> On Nov 8, 2012, at 6:04 PM, Andrey Ilinykh <ailinykh@gmail.com> wrote:
>
> What is the size of columns? Probably those two are huge.
>
>
> On Thu, Nov 8, 2012 at 4:01 AM, André Cruz <andre.cruz@co.sapo.pt> wrote:
>
>> 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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