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Re: AW: AW: Compressed Pristines (Custom Format?)

From: Ashod Nakashian <ashodnakashian_at_yahoo.com>
Date: Mon, 26 Mar 2012 00:54:13 -0700 (PDT)

----- Original Message -----
> From: Markus Schaber <m.schaber_at_3s-software.com>
> To: Ashod Nakashian <ashodnakashian_at_yahoo.com>
> Cc: "dev_at_subversion.apache.org" <dev_at_subversion.apache.org>
> Sent: Sunday, March 25, 2012 11:28 PM
> Subject: AW: AW: Compressed Pristines (Custom Format?)
>
> Hi,
>
>> Von: Ashod Nakashian [mailto:ashodnakashian_at_yahoo.com]
>>
>> >The disadvantage clearly is that we need a few more bits when storing
>> that metadata in the SQLite database, instead of in our own file. But in
>> my eyes, this few bytes do not outweigh the overhead of inventing our own
>> metadata storage format, including correct synchronization, transaction
>> safety etc, which are already provided reliably by sqlite.
>>
>> The overhead in size isn't an issue (at least not a major one) rather
> the
>> overhead of *speed* is. At least that's my argument. I need to expand
> that
>> section with both approaches with pros/cons, but first let's agree on
> the
>> topic debated: to custom format, or to not.
>
> My guess is:
> - For reading, the sqlite approach is not measurable slower, as we have to read
> the wc.db pristine table nevertheless. Reading 3 additional columns is not more
> effort than reading some data from a different file.
>
> - For writing/updating, my guess is that the processing amount of
> (re)-compressing the pristine data, writing it back to disk etc. is at least one
> magnitude larger than the amount we need for both updating the row in the wc.db
> or updating the extra file, so for a first implementation, we can go the easier
> way, which is storing in wc.db in my eyes.
>

I've been convinced that wc.db is a good approach for the metadata and unless we have real numbers/facts to the contrary we shouldn't attempt to solve inexistent problems. The major topic of debate at this point remains the compressed file storage.

-Ash

>
> Best regards
>
> Markus Schaber
> --
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Received on 2012-03-26 09:54:55 CEST

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