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Posted to issues@hive.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2021/12/13 17:44:00 UTC
[jira] [Work logged] (HIVE-25800) loadDynamicPartitions in Hive.java should not load all partitions of a managed table
[ https://issues.apache.org/jira/browse/HIVE-25800?focusedWorklogId=695244&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-695244 ]
ASF GitHub Bot logged work on HIVE-25800:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 13/Dec/21 17:43
Start Date: 13/Dec/21 17:43
Worklog Time Spent: 10m
Work Description: sourabh912 opened a new pull request #2868:
URL: https://github.com/apache/hive/pull/2868
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### What changes were proposed in this pull request?
HIVE-20661 added an improvement in loadDynamicPartitions() api in Hive.java to not add partitions one
by one in HMS. It used to fetch all the existing partitions for a table from HMS and compare that with
dynamic partitions list to decide old and new partitions to be added to HMS (in batches). The call to
fetch all partitions has introduced a performance regression for tables with large number of
partitions (of the order of 100K).
This is fixed for external tables in HIVE-25178. However for ACID tables there is an open Jira HIVE-25187.
Until we have an appropriate fix in HIVE-25187,we can skip fetching all partitions. Instead, in the
threadPool which loads each partition individually,call getPartition() to check if the partition already
exists in HMS or not. This will introduce additional getPartition() call for every partition to be loaded
dynamically but does not fetch all existing partitions for a table anymore.
### Why are the changes needed?
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### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Since it is an improvement in existing logic, therefore relying on existing tests.
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Issue Time Tracking
-------------------
Worklog Id: (was: 695244)
Remaining Estimate: 0h
Time Spent: 10m
> loadDynamicPartitions in Hive.java should not load all partitions of a managed table
> -------------------------------------------------------------------------------------
>
> Key: HIVE-25800
> URL: https://issues.apache.org/jira/browse/HIVE-25800
> Project: Hive
> Issue Type: Improvement
> Components: Hive
> Reporter: Sourabh Goyal
> Assignee: Sourabh Goyal
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> HIVE-20661 added an improvement in loadDynamicPartitions() api in Hive.java to not add partitions one by one in HMS. As part of that improvement, following code was introduced:
> {code:java}
> // fetch all the partitions matching the part spec using the partition iterable
> // this way the maximum batch size configuration parameter is considered
> PartitionIterable partitionIterable = new PartitionIterable(Hive.get(), tbl, partSpec,
> conf.getInt(MetastoreConf.ConfVars.BATCH_RETRIEVE_MAX.getVarname(), 300));
> Iterator<Partition> iterator = partitionIterable.iterator();
> // Match valid partition path to partitions
> while (iterator.hasNext()) {
> Partition partition = iterator.next();
> partitionDetailsMap.entrySet().stream()
> .filter(entry -> entry.getValue().fullSpec.equals(partition.getSpec()))
> .findAny().ifPresent(entry -> {
> entry.getValue().partition = partition;
> entry.getValue().hasOldPartition = true;
> });
> } {code}
> The above code fetches all the existing partitions for a table from HMS and compare that dynamic partitions list to decide old and new partitions to be added to HMS (in batches). The call to fetch all partitions has introduced a performance regression for tables with large number of partitions (of the order of 100K).
>
> This is fixed for external tables in https://issues.apache.org/jira/browse/HIVE-25178. However for ACID tables there is an open Jira(HIVE-25187). Until we have an appropriate fix in HIVE-25187, we can apply the following:
> Skip fetching all partitions. Instead, in the threadPool which loads each partition individually, call get_partition() to check if the partition already exists in HMS or not.
> This will introduce additional getPartition() call for every partition to be loaded dynamically but removes fetching all existing partitions for a table.
> I believe this is fine since for tables with small number of existing partitions in HMS - getPartitions() won't add too much overhead but for tables with large number of existing partitions, it will certainly avoid getting all partitions from HMS
> cc - [~lpinter] [~ngangam]
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