[jira] [Commented] (HIVE-22947) The method getTableObjectsByName() in HiveMetaStoreClient.java is slow

["Fang-Yu Rao (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-22947?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17048079#comment-17048079 ] 

Fang-Yu Rao commented on HIVE-22947:
------------------------------------

There is an IMPALA JIRA at https://issues.apache.org/jira/browse/IMPALA-9363 that would greatly benefit from this Hive JIRA.

 

> The method getTableObjectsByName() in HiveMetaStoreClient.java is slow
> ----------------------------------------------------------------------
>
>                 Key: HIVE-22947
>                 URL: https://issues.apache.org/jira/browse/HIVE-22947
>             Project: Hive
>          Issue Type: Improvement
>          Components: Standalone Metastore
>            Reporter: Fang-Yu Rao
>            Priority: Major
>         Attachments: Benchmark_related_to_IMPALA-9363.pdf
>
>
> The RPC of {{getTableObjectsByName()}} in {{HiveMetaStoreClient.java}} ([https://github.com/apache/hive/blob/master/standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/HiveMetaStoreClient.java#L2111-L2114]) is very slow. Specifically, according to an empirical evaluation, to load the complete metadata of all the tables under a database consisting of 40,000 tables, it takes at least 170 seconds for {{getTableObjectsByName()}} to complete, whereas it only takes less than 0.5 second for {{getAllTables()}} ([https://github.com/apache/hive/blob/master/standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/HiveMetaStoreClient.java#L2281-L2288]).
> In some use cases, not all the fields under the class of {{org.apache.hadoop.hive.metastore.api.Table}} are required. For instance, if a client would only like to determine the type of a table, e.g., an HDFS table or a Kudu table, then it should suffice to only load the field of {{sd}}, which is of class {{org.apache.hadoop.hive.metastore.api.StorageDescriptor}}. It would be great if {{getTableObjectsByName()}} could be made more fine-grained so that only those required fields specified by the client are retrieved, which could also possibly reduce the time spent on this RPC.
> A spreadsheet is also attached ([^Benchmark_related_to_IMPALA-9363.pdf]), where the detailed experimental results are provided. In the experiment, as a client of Hive metastore, the {{catalogd}} of Impala calls {{getTableObjectsByName()}} to retrieve the complete metadata of tables under a database having 40,000 tables.
>  



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