[HIVE-17683] Add explain locks <sql> command

• Type: New Feature
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 3.2.0
• Component/s: Transactions
• Release Note: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Explain#LanguageManualExplain-TneLOCKSClause
• Assignee: Igor Kryvenko
• Reporter: Eugene Koifman
• Created: 03/Oct/17 21:10
• Updated: 01/Oct/19 22:06
• Resolved: 04/Aug/18 00:45

Description

Explore if it's possible to add info about what locks will be asked for to the query plan.
Lock acquisition (for Acid Lock Manager) is done in DbTxnManager.acquireLocks() which is called once the query starts running. Would need to refactor that.