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https://issues.apache.org/jira/browse/DRILL-5516?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16013882#comment-16013882
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ASF GitHub Bot commented on DRILL-5516:
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Github user arina-ielchiieva commented on the issue:
https://github.com/apache/drill/pull/839
This approach does not allow Hbase to use more memory, actually it limits
memory usage.. Previously when batch size was limited to 4000 rows, we could
have one batch using ~3 GB.
> Use max allowed allocated memory when defining batch size for hbase record
> reader
> ---------------------------------------------------------------------------------
>
> Key: DRILL-5516
> URL: https://issues.apache.org/jira/browse/DRILL-5516
> Project: Apache Drill
> Issue Type: Improvement
> Components: Storage - HBase
> Affects Versions: 1.10.0
> Reporter: Arina Ielchiieva
> Assignee: Arina Ielchiieva
>
> If early limit 0 optimization is set to true (alter session set
> `planner.enable_limit0_optimization` = true), when executing limit 0 queries
> Drill will return data type from available metadata if possible.
> When Drill can not determine data types from metadata (or if early limit 0
> optimization is set to false), Drill will read first batch of data and
> determine schema.
> Hbase reader determines max batch size using magic number (4000) which can
> lead to OOM when row size is large. The overall vector/batch size issue will
> be reconsidered in future releases.This is temporary fix to avoid OOM.
> Instead of using rows number, we will use max allowed allocated memory which
> will default to 64 mb. If first row in batch is larger than allowed default,
> it will be written in batch but batch will contain only this row.
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