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https://issues.apache.org/jira/browse/HIVE-25800?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17458509#comment-17458509
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Sourabh Goyal edited comment on HIVE-25800 at 12/13/21, 4:20 PM:
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Just realized that a part of it is already fixed in
https://issues.apache.org/jira/browse/HIVE-25178.
was (Author: sourabh912):
Just realized that this is already fixed in
https://issues.apache.org/jira/browse/HIVE-25178. Marking this as duplicate
> loadDynamicPartitions in Hive.java should not load all partitions of a table
> from HMS
> --------------------------------------------------------------------------------------
>
> 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
>
> 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).
>
> The fix is to 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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