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From Denis Magda <dma...@gridgain.com>
Subject Possible optimizations for SQL + Off-heap
Date Thu, 21 Apr 2016 13:48:14 GMT
Sergi, Igniters,

Big deployments store enormous amount of data in off-heap. If to keep using such deployments
under high load executing SQL queries and basic cache operations in parallel then it’s easy
to see that Java heap pressure grows due to the bigger number of short live objects creation.


I’ve been investigating Ignite code and noted the following

1) During SQL query execution off-heap data is unswapped and stored in BinaryObjectImpl wrapper
for columns comparison. Also as I see the same happens when an index is updated.

2) Off-heap index tree is snapshotable. Taking into account hight update and query rates,
Java heap will be populated with much more short snapshots. 

Actually I think that we can try to lower the impact caused by 1) by trying reusing BinaryObjectOffHeapImpl
that allows to access fields directly working with off-heap. What do you think, any obstacles?

In regards to the second. Is there any alternatives to snapshotable tree in general?

—
Denis
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