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https://issues.apache.org/jira/browse/HIVE-14233?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eugene Koifman updated HIVE-14233:
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Comment: was deleted
(was: [~saketj], I left 1 last comment on RB but it's a nit
+1 pending tests)
> Improve vectorization for ACID by eliminating row-by-row stitching
> ------------------------------------------------------------------
>
> Key: HIVE-14233
> URL: https://issues.apache.org/jira/browse/HIVE-14233
> Project: Hive
> Issue Type: New Feature
> Components: Transactions, Vectorization
> Reporter: Saket Saurabh
> Assignee: Saket Saurabh
> Attachments: HIVE-14233.01.patch, HIVE-14233.02.patch,
> HIVE-14233.03.patch, HIVE-14233.04.patch, HIVE-14233.05.patch,
> HIVE-14233.06.patch, HIVE-14233.07.patch, HIVE-14233.08.patch,
> HIVE-14233.09.patch, HIVE-14233.10.patch, HIVE-14233.11.patch
>
>
> This JIRA proposes to improve vectorization for ACID by eliminating
> row-by-row stitching when reading back ACID files. In the current
> implementation, a vectorized row batch is created by populating the batch one
> row at a time, before the vectorized batch is passed up along the operator
> pipeline. This row-by-row stitching limitation was because of the fact that
> the ACID insert/update/delete events from various delta files needed to be
> merged together before the actual version of a given row was found out.
> HIVE-14035 has enabled us to break away from that limitation by splitting
> ACID update events into a combination of delete+insert. In fact, it has now
> enabled us to create splits on delta files.
> Building on top of HIVE-14035, this JIRA proposes to solve this earlier
> bottleneck in the vectorized code path for ACID by now directly reading row
> batches from the underlying ORC files and avoiding any stitching altogether.
> Once a row batch is read from the split (which may be on a base/delta file),
> the deleted rows will be found by cross-referencing them against a data
> structure that will just keep track of deleted events (found in the
> deleted_delta files). This will lead to a large performance gain when reading
> ACID files in vectorized fashion, while enabling further optimizations in
> future that can be done on top of that.
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