I'm been using a self-describing value encoding for a decade and a half.
It's denser and cheaper to compress and decompress than the existing run
length encoding, though I'm not sure that compressing version delta would
be a lot of fun, but probably some clever fellow can think of a good
algorithm.
On Monday, February 23, 2015, Slavomir Skopalik <skopa...@elektlabs.cz>
wrote:
> Hi,
> for FB3 I will recomend more effective algoritm than hacking this current
> one.
> If you are interested, I can specify.
>
> I was made another test with release build windows 64 bit and results:
>
> DB size decrese from 90GB -> 60 GB.
> Some select count(*) from table like this one:
>
> Create Table ProductDataEx (
> idProduct TLongInt NOT NULL,
> idMeasurand Smallint NOT NULL,
> idMeasurementMode TSmallInt NOT NULL,
> ValIndex Smallint Default 0 NOT NULL,
> idPeople TSmallInt NOT NULL,
> tDate TimeDateFutureCheck NOT NULL,
> Value1 Double precision NOT NULL,
> Description TMemo,
> Constraint pk_ProductDataEx Primary Key (idProduct,idMeasurand,
> idMeasurementMode,ValIndex)
> );
>
> Decrease from ~150s(any run) -> 52s for first run and 36s another run.
>
> This modifycation can read old DB, but after write, previous server will
> failed.
> So, if I can I will vote to 2.5.4 (FB3 is so far).
>
> Also I was made some speed optimization, this version is faster, then
> previous one.
>
> If somebody else is interesting in this, I can put my private buid for
> Win64 on my web site.
>
> Best regards Slavek
>
> Ing. Slavomir Skopalik
> Executive Head
> Elekt Labs s.r.o.
> Collection and evaluation of data from machines and laboratories
> by means of system MASA (http://www.elektlabs.cz/m2demo)
> -----------------------------------------------------------------
> Address:
> Elekt Labs s.r.o.
> Chaloupky 158
> 783 72 Velky Tynec
> Czech Republic
> ---------------------------------------------------------------
> Mobile: +420 724 207 851
> icq:199 118 333
> skype:skopaliks
> e-mail:skopa...@elektlabs.cz
> http://www.elektlabs.cz
>
> On 23.2.2015 7:38, Dmitry Yemanov wrote:
>
>> I didn't look at the code closely, but the idea is more or less the same
>> as I was considering for CORE-4401. I just wanted to use the control
>> char of zero for that purpose, as it's practically useless for either
>> compressible or non-compressible runs.
>>
>> The new encoding affects the ODS, so it cannot be used in the v2.5
>> series (it may be possible with ODS 11.3 but I don't think we need a
>> minor ODS change in v2.5). But it surely could be applied to v3 after
>> review and we don't have to worry about backward compatibility in ODS 12.
>>
>>
>> Dmitry
>>
>>
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>
--
Jim Starkey
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