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Posted to issues@hive.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2020/06/23 07:42:00 UTC
[jira] [Work logged] (HIVE-20890) ACID: Allow whole table ReadLocks
to skip all partition locks
[ https://issues.apache.org/jira/browse/HIVE-20890?focusedWorklogId=449674&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-449674 ]
ASF GitHub Bot logged work on HIVE-20890:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 23/Jun/20 07:41
Start Date: 23/Jun/20 07:41
Worklog Time Spent: 10m
Work Description: deniskuzZ opened a new pull request #1166:
URL: https://github.com/apache/hive/pull/1166
…ocks
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Issue Time Tracking
-------------------
Worklog Id: (was: 449674)
Remaining Estimate: 0h
Time Spent: 10m
> ACID: Allow whole table ReadLocks to skip all partition locks
> -------------------------------------------------------------
>
> Key: HIVE-20890
> URL: https://issues.apache.org/jira/browse/HIVE-20890
> Project: Hive
> Issue Type: Improvement
> Components: Transactions
> Reporter: Gopal Vijayaraghavan
> Assignee: Denys Kuzmenko
> Priority: Major
> Attachments: HIVE-20890.1.patch, HIVE-20890.2.patch, HIVE-20890.3.patch, HIVE-20890.4.patch, HIVE-20890.5.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> HIVE-19369 proposes adding a EXCL_WRITE lock which does not wait for any SHARED_READ locks for read operations - in the presence of that lock, the insert overwrite no longer takes an exclusive lock.
> The only exclusive operation will be a schema change or drop table, which should take an exclusive lock on the entire table directly.
> {code}
> explain locks select * from tpcds_bin_partitioned_orc_1000.store_sales where ss_sold_date_sk=2452626
> +----------------------------------------------------+
> | Explain |
> +----------------------------------------------------+
> | LOCK INFORMATION: |
> | tpcds_bin_partitioned_orc_1000.store_sales -> SHARED_READ |
> | tpcds_bin_partitioned_orc_1000.store_sales.ss_sold_date_sk=2452626 -> SHARED_READ |
> +----------------------------------------------------+
> {code}
> So the per-partition SHARED_READ locks are no longer necessary, if the lock builder already includes the table-wide SHARED_READ locks.
> The removal of entire partitions is the only part which needs to be taken care of within this semantics as row-removal instead of directory removal (i.e "drop partition" -> "truncate partition" and have the truncation trigger a whole directory cleaner, so that the partition disappears when there are 0 rows left).
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