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From Dmitriy Pavlov <dpavlov....@gmail.com>
Subject Re: Compression prototype
Date Thu, 23 Aug 2018 12:17:05 GMT
Ok, thanks. IMO we need to store the dictionary in Durable memory before
merging into master.

чт, 23 авг. 2018 г. в 15:12, Ilya Kasnacheev <ilya.kasnacheev@gmail.com>:

> Hello!
>
> Currently, the dictionary for decompression is only stored on heap. After
> restart there's compressed data in the PDS, but there's no dictionary :)
>
> Regards,
>
> --
> Ilya Kasnacheev
>
> 2018-08-23 14:58 GMT+03:00 Dmitriy Pavlov <dpavlov.spb@gmail.com>:
>
> > Hi Ilya,
> >
> > Thank you for sharing this here. I believe this contribution will be
> > accepted by the Community. Moreover, it shows so remarkable performance
> > boost.
> >
> > I'm pretty sure this patch will be reviewed by Ignite Native Persistence
> > experts soon.
> >
> > What do you mean by can't survive PDS node restart?
> >
> > Sincerely,
> > Dmitriy Pavlov
> >
> > чт, 23 авг. 2018 г. в 13:09, Ilya Kasnacheev <ilya.kasnacheev@gmail.com
> >:
> >
> > > Hello!
> > >
> > > I want to share with the developer community my compression prototype.
> > >
> > > Long story short, it compresses BinaryObject's byte[] as they are
> written
> > > to Durable Memory page, operating on a pre-built dictionary. Typical
> > > compression ratio is 0.4 (meaning 2.5x compression) using custom
> > > LZW+Huffman. Metadata, indexes and primitive values are unaffected
> > > entirely.
> > >
> > > This is akin to DB2's table-level compression[1] but independently
> > > invented.
> > >
> > > On Yardstick tests performance hit is -6% with PDS and up to -25% (in
> > > throughput) with In-Memory loads. It also means you can fit ~twice as
> > much
> > > data into the same IM cluster, or have higher ram/disk ratio with PDS
> > > cluster, saving on hardware or decreasing latency.
> > >
> > > The code is available as PR 4295[2] (set IGNITE_ENABLE_COMPRESSION=true
> > to
> > > activate). Note that it will not presently survive a PDS node restart.
> > > The impact is very small, the patch should be applicable to most 2.x
> > > releases.
> > >
> > > Sure there's a long way before this prototype can have hope of being
> > > included, but first I would like to hear input from fellow igniters.
> > >
> > > See also IEP-20[3].
> > >
> > > 1.
> > >
> > > https://www.ibm.com/support/knowledgecenter/en/SSEPGG_10.
> > 5.0/com.ibm.db2.luw.admin.dbobj.doc/doc/c0052331.html
> > > 2. https://github.com/apache/ignite/pull/4295
> > > 3.
> > >
> > > https://cwiki.apache.org/confluence/display/IGNITE/IEP-
> > 20%3A+Data+Compression+in+Ignite
> > >
> > > Regards,
> > >
> > > --
> > > Ilya Kasnacheev
> > >
> >
>

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