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From "Stanislav Lukyanov (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IGNITE-9526) Allow explicitly setting index inline size for Java objects
Date Mon, 10 Sep 2018 19:45:00 GMT
Stanislav Lukyanov created IGNITE-9526:
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             Summary: Allow explicitly setting index inline size for Java objects
                 Key: IGNITE-9526
                 URL: https://issues.apache.org/jira/browse/IGNITE-9526
             Project: Ignite
          Issue Type: Bug
          Components: sql
            Reporter: Stanislav Lukyanov
            Assignee: Stanislav Lukyanov


Currently Ignite never inlines indexed objects when they are POJOs. It makes sense, as there
is currently no way of inlining a POJO other than by inlining the binary object, and the headers
of the binary objects (i.e. their first 24 bytes) are usually the same for the same indexed
field.

However, this approach has downsides.
Silently ignoring the specified inline size might be surprising for a user willing to trade
(a lot of) memory for speed and setting a large inline size for that purpose.
On the other hand, inlining headers and just several first bytes of POJOs in binary format
has proven to be beneficial. It is especially beneficial in case page replacements are happening,
as this greatly reduces the number of data pages required to traverse an index tree.

The proposal is to allow POJO inlining in case the inline size is given for the specific POJO
field. So, unlike strings and byte arrays, POJOs will not use the max inline size by default
- as in most cases inlining POJOs isn't going to help.



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