[jira] [Commented] (ASTERIXDB-3172) Result tuples unnecessarily serialized twice

["ASF subversion and git services (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ASTERIXDB-3172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17718705#comment-17718705 ] 

ASF subversion and git services commented on ASTERIXDB-3172:
------------------------------------------------------------

Commit 4f18020796c78bb4455bd7bec2946f83650da427 in asterixdb's branch refs/heads/master from Ali Alsuliman
[ https://gitbox.apache.org/repos/asf?p=asterixdb.git;h=4f18020796 ]

[ASTERIXDB-3172][RT] Do not reset byte array holding serialized tuple

- user model changes: no
- storage format changes: no
- interface changes: no

Details:
In the ResultWriterOperatorDescriptor, the frameOutputStream
should not reset the byte array that holds the serialized
tuple when adding the tuple to the frame (appendTuple()).
This leads to having to re-serialized the tuple again into
the byte array when the frame couldn't appendTuple() due to
being full of tuples.

Change-Id: Ibaaac339065a30f58e2bc7f39800a506f959549d
Reviewed-on: https://asterix-gerrit.ics.uci.edu/c/asterixdb/+/17501
Integration-Tests: Jenkins <je...@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <je...@fulliautomatix.ics.uci.edu>
Reviewed-by: Murtadha Hubail <mh...@apache.org>


> Result tuples unnecessarily serialized twice
> --------------------------------------------
>
>                 Key: ASTERIXDB-3172
>                 URL: https://issues.apache.org/jira/browse/ASTERIXDB-3172
>             Project: Apache AsterixDB
>          Issue Type: Bug
>          Components: RT - Runtime
>    Affects Versions: 0.9.6
>            Reporter: Ali Alsuliman
>            Assignee: Ali Alsuliman
>            Priority: Major
>             Fix For: 0.9.9
>
>
> The ResultWriterOperatorDescriptor is the operator that persists the query result to disk. Each partition persists its portion of the result by serializing the tuples (that are in ADM format) as JSON strings into a byte array. This byte array that represents the JSON is added into a frame that is used to write the accumulated tuples to the result file. If the byte array is added to the frame successfully, the byte array is reset and the next tuple is serialized into it. However, if the byte array couldn't be added to the frame because the frame is full, the frame is flushed to disk and is emptied but also the byte array is reset at the same time. This leads to having to re-serialized the tuple again into the byte array and adding it to the frame. This becomes expensive especially for large tuples.
> The byte array should not be reset upon flushing the frame when the frame cannot hold it. Instead, the frame should be flushed without reseting the byte array. Then, adding the byte array to the frame should be attempted again. When adding the byte array is successful, it should be reset.



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