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From Vyacheslav Daradur <daradu...@gmail.com>
Subject Re: Compression prototype
Date Tue, 28 Aug 2018 15:29:54 GMT
I have another suggestion which may help us reduce objects size
extremely - implementing some kind of SQL Scheme.

For now, BinaryObject's format is too excessive - each serialized
object stores offset of every serialized field even if the offset can
be easily calculated.

If we move this metadata from a serialized object to a separate entity
- this will reduce an object's size.
On Mon, Aug 27, 2018 at 2:53 PM Vyacheslav Daradur <daradurvs@gmail.com> wrote:
>
> According to my benchmarks - zstd compression algorithm [1] looks very
> interesting, it has a high compression ratio with quite good speed.
> AFAIK it supports external dictionaries, but I'm not sure about using
> it with "on the fly building" dictionaries. Anyway, have look at (it
> has ASF 2.0 friendly license).
>
> Also, here is data generator / loader [1]. If it will be useful for
> you we should ask Nikolay Izhikov to share public docs to start.
>
> [1] https://github.com/facebook/zstd
> [2] https://github.com/nizhikov/ignite-cod-data-loader
> On Mon, Aug 27, 2018 at 2:11 PM Ilya Kasnacheev
> <ilya.kasnacheev@gmail.com> wrote:
> >
> > Hello Vyacheslav!
> >
> > Unfortunately I have not found any efficient algorithms that will allow me
> > to use external dictionary as a pre-processed data structure. If plain gzip
> > is used without dictionary, the compression is around 0.7, as opposed to
> > 0.4 that I will get with custom implementation, AFAIR the performance was
> > also worse. I didn't really try it with dictionary, but I assume
> > performance will be even worse since it will have to scan dictionary before
> > getting to actual data.
> >
> > We have such a huge array of tests that we can just run them all with
> > compression enabled, see if there are any new failures. But the impact of
> > my commit is fairly low, it is only triggered when data is written to page
> > (maybe to WAL also?), and we don't really do much frivolous stuff to pages.
> >
> > Still, I am very much interested in finding existing compression
> > implementations with support of external dictionary; I am also very much
> > interested in having different implementations of compression for Apache
> > Ignite (such as per page compression) and comparing them by benchmark and
> > by code impact. I am also very interested in large standard datasets for
> > Apache Ignite (or generators thereof) so that we can run precise benchmarks
> > on various compression schemes. If you have any of the following, please
> > get back to me.
> >
> > Regards,
> > --
> > Ilya Kasnacheev
> >
> >
> > пн, 27 авг. 2018 г. в 11:35, Vyacheslav Daradur <daradurvs@gmail.com>:
> >
> > > Hi Igniters!
> > >
> > > Ilya, I'm glad to see one more person who is interested in the
> > > compression feature in Ignite.
> > >
> > > I looked through the pull request and want to share following thoughts:
> > >
> > > It's very dangerous using a custom algorithm in this way - you store
> > > serialized data separate from a dictionary and there are a lot of
> > > points when we may lose data: rebalancing, serialization errors, node
> > > rebooting and so on.
> > >
> > > I'd suggest the following ways to improve reliability:
> > > - use well know algorithms: zstd, deflater, lzma, gzip e.g. that
> > > allows us to decompress data in any situation
> > > - store the dictionary inside page with data
> > >
> > > Also, we have a lot of discussions [1] [2] about compression on
> > > BinaryObject and BinaryMarshaller level and Vladimir Ozerov was
> > > strictly against a compression on this level.
> > > If something has changed since then, you may look through [1] [2] [3]
> > > I've done a lot of research in algorithms comparison it may be useful
> > > for you.
> > >
> > > [1]
> > > http://apache-ignite-developers.2346864.n4.nabble.com/Data-compression-in-Ignite-2-0-td10099.html
> > > [2]
> > > http://apache-ignite-developers.2346864.n4.nabble.com/Data-compression-in-Ignite-td20679.html
> > > [3] https://issues.apache.org/jira/browse/IGNITE-3592
> > > [4] https://issues.apache.org/jira/browse/IGNITE-5226
> > > [5] https://github.com/daradurvs/ignite-compression
> > > On Sat, Aug 25, 2018 at 2:51 AM Denis Magda <dmagda@apache.org> wrote:
> > > >
> > > > >
> > > > > Currently, the dictionary for decompression is only stored on heap.
> > > After
> > > > > restart there's compressed data in the PDS, but there's no dictionary
> > > :)
> > > >
> > > >
> > > > Basically, it means that I've lost my data, right? How about persisting
> > > > data to disk.
> > > >
> > > > Overall, we need Vladimir Ozerov to check the contribution. He was the
> > > one
> > > > who sponsored the IEP and knows the area best.
> > > >
> > > > --
> > > > Denis
> > > >
> > > > On Fri, Aug 24, 2018 at 4:31 AM Ilya Kasnacheev <
> > > ilya.kasnacheev@gmail.com>
> > > > wrote:
> > > >
> > > > > Hello!
> > > > >
> > > > > It is somewhat a part of IEP-20, since I have updated it with this
> > > > > particular direction.
> > > > >
> > > > > Regards,
> > > > >
> > > > > --
> > > > > Ilya Kasnacheev
> > > > >
> > > > > 2018-08-24 2:56 GMT+03:00 Denis Magda <dmagda@apache.org>:
> > > > >
> > > > > > Hi Ilya,
> > > > > >
> > > > > > Sounds terrific! Is this part of the following Ignite enhancement
> > > > > proposal?
> > > > > > https://cwiki.apache.org/confluence/display/IGNITE/IEP-
> > > > > > 20%3A+Data+Compression+in+Ignite
> > > > > >
> > > > > > --
> > > > > > Denis
> > > > > >
> > > > > > On Thu, Aug 23, 2018 at 5:17 AM Ilya Kasnacheev <
> > > > > ilya.kasnacheev@gmail.com
> > > > > > >
> > > > > > wrote:
> > > > > >
> > > > > > > Hello!
> > > > > > >
> > > > > > > My plan was to add a compression section to cache configuration,
> > > where
> > > > > > you
> > > > > > > can enable compression, enable key compression (which has
heavier
> > > > > > > performance implications), adjust dictionary gathering
settings,
> > > and in
> > > > > > the
> > > > > > > future possibly choose betwen algorithms. In fact I'm not
sure,
> > > since
> > > > > my
> > > > > > > assumption is that you can always just use latest&greatest,
but
> > > maybe
> > > > > we
> > > > > > > can have e.g. very fast and not very strong vs. slower
but stronger
> > > > > one.
> > > > > > >
> > > > > > > I'm not sure yet if we should share dictionary between
all caches
> > > vs.
> > > > > > > having separate dictionary for every cache.
> > > > > > >
> > > > > > > With regards to data format, of course there will be room
for
> > > further
> > > > > > > extension.
> > > > > > >
> > > > > > > Regards,
> > > > > > >
> > > > > > > --
> > > > > > > Ilya Kasnacheev
> > > > > > >
> > > > > > > 2018-08-23 15:13 GMT+03:00 Sergey Kozlov <skozlov@gridgain.com>:
> > > > > > >
> > > > > > > > Hi Ilya
> > > > > > > >
> > > > > > > > Is there a plan to introduce it as an option of Ignite
> > > configuration?
> > > > > > In
> > > > > > > > that instead the boolean type I suggest to use the
enum and
> > > reserve
> > > > > the
> > > > > > > > ability to extend compressions algorithms in future
> > > > > > > >
> > > > > > > > On Thu, Aug 23, 2018 at 1:09 PM, Ilya Kasnacheev <
> > > > > > > > ilya.kasnacheev@gmail.com>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > 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
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > --
> > > > > > > > Sergey Kozlov
> > > > > > > > GridGain Systems
> > > > > > > > www.gridgain.com
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > >
> > >
> > >
> > > --
> > > Best Regards, Vyacheslav D.
> > >
>
>
>
> --
> Best Regards, Vyacheslav D.



-- 
Best Regards, Vyacheslav D.

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