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https://issues.apache.org/jira/browse/TEZ-2574?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14599606#comment-14599606
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Saikat commented on TEZ-2574:
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another example would be, say 48mb block and key size 10mb, value size 10mb
-in old implementation, 48 mb will be split into 16 mb meta space and 32mb
value space. and only 1 KV pair will fit.
-in new implementation, 48 mb will be split into 8mb meta space and 40mb value
space, and 2KV pair can fit in a span.
> Make a better metadata Value split choice in Pipeline sort
> ----------------------------------------------------------
>
> Key: TEZ-2574
> URL: https://issues.apache.org/jira/browse/TEZ-2574
> Project: Apache Tez
> Issue Type: Improvement
> Reporter: Saikat
> Assignee: Saikat
> Attachments: TEZ-2574.patch
>
>
> In the current implementation of pipeline sort, when a new sort span object
> is created with a hard coded value of 1M items and 16 bytes per item.
> According to the present code logic,
> int metasize = METASIZE*maxItems;
> int dataSize = maxItems * perItem;
> if(capacity < (metasize+dataSize)) {
> // try to allocate less meta space, because we have sample data
> metasize = METASIZE*(capacity/(perItem+METASIZE));
> }
> if capacity is less than 32mb, the buffer will be halved into meta and value
> buffers, which is not efficient.
> We need a more generic split, based on the KV pair size written to the buffer.
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