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https://issues.apache.org/jira/browse/HIVE-22947?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dinesh Garg reassigned HIVE-22947:
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Assignee: Thejas Nair
> 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
> Assignee: Thejas Nair
> Priority: Critical
> 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])
> on the same machine.
> 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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