Re: In-Memory Columnar Store

<p dir="ltr">it is interesting idea. For me, a significant information from comparation, so we do some significantly
wrong.Memory engine should be faster naturally, but I don't tkink it can be 1000x.<p dir="ltr">Yesterday we did a some
tests,that shows so for large tables (5G)a our hashing is not effective. Disabling hash join and using merge join
increasedspeed 2x<br /> Dne 9. 12. 2013 20:41 "knizhnik" <<a
href="mailto:knizhnik@garret.ru">knizhnik@garret.ru</a>>napsal(a):<br /> ><br /> > Hello!<br /> ><br />
>I want to annouce my implementation of In-Memory Columnar Store extension for PostgreSQL:<br /> ><br /> >    
 Documentation:<a href="http://www.garret.ru/imcs/user_guide.html">http://www.garret.ru/imcs/user_guide.html</a><br />
>     Sources: <a href="http://www.garret.ru/imcs-1.01.tar.gz">http://www.garret.ru/imcs-1.01.tar.gz</a><br />
><br/> > Any feedbacks, bug reports and suggestions are welcome.<br /> ><br /> > Vertical representation of
datais stored in PostgreSQL shared memory.<br /> > This is why it is important to be able to utilize all available
physicalmemory.<br /> > Now servers with Tb or more RAM are not something exotic, especially in financial world.<br
/>> But there is limitation in Linux with standard 4kb pages  for maximal size of mapped memory segment: 256Gb.<br
/>> It is possible to overcome this limitation either by creating multiple segments - but it requires too much
changesin PostgreSQL memory manager.<br /> > Or just set MAP_HUGETLB flag (assuming that huge pages were allocated
inthe system).<br /> ><br /> > I found several messages related with MAP_HUGETLB flag, the most recent one was
from21 of November:<br /> > <a
href="http://www.postgresql.org/message-id/20131125032920.GA23793@toroid.org">http://www.postgresql.org/message-id/20131125032920.GA23793@toroid.org</a><br
/>><br /> > I wonder what is the current status of this patch?<br /> ><br /> ><br /> ><br /> ><br />
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