> В Вт., 27/09/2011 в 10:54 +0200, Thomas Steinmaurer пишет:
>>
>>> В Вт., 27/09/2011 в 10:23 +0200, Dimitry Sibiryakov пишет:
>>>> 27.09.2011 10:18, Thomas Steinmaurer wrote:
>>>>>> Records are already compressed as delta + RLE. Page level
>> compression is pointless
>>>>>> because page of variable size is a headache.
>>>>>
>>>>> Still fixed page size on disk with compressed data.
>>>>
>>>> And this is exactly why page compression is pointless: you are
>> writing to disk full
>>>> page size anyway, no difference between page with uncompressed data
>> and page with
>>>> compressed data + some filling zeros.
>>>>
>>>
>>> Must say that for example NTFS supports writing compressed pages to
>> disk
>>> and does not fill it with 0, instead puts more data to the page. We
>>> probably can do something like this - when adding new record/version
>> to
>>> the page compress it and when result does not fit, use another page
>> for
>>> that record/version.
>>
>> I don't know what algorith is used here, but AFAIK it decompress
>> stuff
>> before going over the network etc ...
>
> I do not see how is compression in database _file_ related with what is
> travelling over network.

Right, but the same principle applies to network as well. Ok, network
compression has been discussed to death I think.

Regards,
Thomas