[
https://issues.apache.org/jira/browse/HIVE-20890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17289039#comment-17289039
]
Denys Kuzmenko edited comment on HIVE-20890 at 2/23/21, 12:05 PM:
------------------------------------------------------------------
pending lock-free drop partition implementation, current implementation
addresses only HIVE-23714
was (Author: dkuzmenko):
pending lock-free drop partition implementation
> 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
> Labels: pull-request-available
> Fix For: 4.0.0
>
> Attachments: HIVE-20890.1.patch, HIVE-20890.2.patch,
> HIVE-20890.3.patch, HIVE-20890.4.patch, HIVE-20890.5.patch
>
> Time Spent: 1h
> 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).
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
