[
https://issues.apache.org/jira/browse/HIVE-25800?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
ASF GitHub Bot updated HIVE-25800:
----------------------------------
Labels: pull-request-available (was: )
> 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]
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
