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hive.mapjoin.bucket.cache.size

• Default Value: 100hive.metastore.try.direct.sql
• Added In: Hive 0.5.0 (replaced by hive.smbjoin.cache.rows in Hive 0.12.0)

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Whether the Hive metastore should try to use direct SQL queries instead of the DataNucleus for certain read paths. This can improve metastore performance when fetching many partitions or column statistics by orders of magnitude; however, it is not guaranteed to work on all RDBMS-es and all versions. In case of SQL failures, the metastore will fall back to the DataNucleus, so it's safe even if SQL doesn't work for all queries on your datastore. If all SQL queries fail (for example, your metastore is backed by MongoDB), you might want to disable this to save the try-and-fall-back cost.

This can be configured per client basis by using "set metaconf:hive.metastore.try.direct.sql=<value>" command from Hive 0.14.0 with HIVE-7532

hive.metastore.try.direct.sql.ddl

• Default Value: true
• Added In: Hive 0.13.0 with HIVE-5626

Same as hive.metastore.try.direct.sql, for read statements within a transaction that modifies metastore data. Due to non-standard behavior in Postgres, if a direct SQL select query has incorrect syntax or something similar inside a transaction, the entire transaction will fail and fall-back to DataNucleus will not be possible. You should disable the usage of direct SQL inside transactions if that happens in your case.

This can be configured per client basis by using "set metaconf:hive.metastore.try.direct.sql.ddl=<value>" command from Hive 0.14.0 with HIVE-7532

HiveServer2

HiveServer2 was added in Hive 0.11.0 with HIVE-2935.  For more information see Setting Up HiveServer2 and HiveServer2 Clients.

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