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https://issues.apache.org/jira/browse/HIVE-23597?focusedWorklogId=476948&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-476948
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ASF GitHub Bot logged work on HIVE-23597:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 01/Sep/20 00:47
Start Date: 01/Sep/20 00:47
Worklog Time Spent: 10m
Work Description: github-actions[bot] commented on pull request #1081:
URL: https://github.com/apache/hive/pull/1081#issuecomment-684124193
This pull request has been automatically marked as stale because it has not
had recent activity. It will be closed if no further activity occurs.
Feel free to reach out on the d...@hive.apache.org list if the patch is in
need of reviews.
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Issue Time Tracking
-------------------
Worklog Id: (was: 476948)
Time Spent: 1.5h (was: 1h 20m)
> VectorizedOrcAcidRowBatchReader::ColumnizedDeleteEventRegistry reads delete
> delta directories multiple times
> ------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-23597
> URL: https://issues.apache.org/jira/browse/HIVE-23597
> Project: Hive
> Issue Type: Improvement
> Reporter: Rajesh Balamohan
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> [https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/io/orc/VectorizedOrcAcidRowBatchReader.java#L1562]
> {code:java}
> try {
> final Path[] deleteDeltaDirs = getDeleteDeltaDirsFromSplit(orcSplit);
> if (deleteDeltaDirs.length > 0) {
> int totalDeleteEventCount = 0;
> for (Path deleteDeltaDir : deleteDeltaDirs) {
> {code}
>
> Consider a directory layout like the following. This was created by having
> simple set of "insert --> update --> select" queries.
>
> {noformat}
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/base_0000001
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/base_0000002
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000003_0000003_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000004_0000004_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000005_0000005_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000006_0000006_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000007_0000007_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000008_0000008_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000009_0000009_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000010_0000010_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000011_0000011_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000012_0000012_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delete_delta_0000013_0000013_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000003_0000003_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000004_0000004_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000005_0000005_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000006_0000006_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000007_0000007_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000008_0000008_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000009_0000009_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000010_0000010_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000011_0000011_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000012_0000012_0000
> /warehouse-1591131255-hl5z/warehouse/tablespace/managed/hive/sequential_update_4/delta_0000013_0000013_0000
> {noformat}
>
> Orcsplit contains all the delete delta folder information. For the directory
> layout like this, it would create {{~12 splits}}. For every split, it
> constructs "ColumnizedDeleteEventRegistry" in VRBAcidReader and ends up
> reading all these delete delta folders multiple times.
> In this case, it would read it approximately {{121 times!}}.
> This causes huge delay in running simple queries like "{{select * from
> tab_x}}" in cloud storage.
>
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