Vladimir Ozerov created IGNITE-5991:
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Summary: SQL: create prototype for map query execution without
moving full ResultSet to memory
Key: IGNITE-5991
URL: https://issues.apache.org/jira/browse/IGNITE-5991
Project: Ignite
Issue Type: Improvement
Components: sql
Affects Versions: 2.1
Reporter: Vladimir Ozerov
Assignee: Vladimir Ozerov
Fix For: 2.2
Currently we move the whole {{ResultSet}} to memory when executing SQL query on
mapper. If result set is large enough, this could easily bring server down due
to high GC pressure or even OOME.
To avoid that we should stream H2's {{ResultSet}} to our own consumer, which
will construct a page and send it to the client When a page is sent, consumer
will block current thread until "next page request" is received. This approach
has disadvantage - query thread will be blocked. However, implementation should
be fairly easy and will allow us to avoid OOMEs on server. In future we will
improve it to minimize blocking (or even avoid it completely).
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