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https://issues.apache.org/jira/browse/HIVE-3561?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13721883#comment-13721883
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Edward Capriolo commented on HIVE-3561:
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I think supporting two query languages is nuts. What is the obsession with SQL
compliance? I like hive's query language. It has less constructs and that makes
it easier to read and write queries. Also, knowing hive means learning and
understanding map reduce you can make things too easy for people and they get
into anti-patterns. Having a new parser or two parsers activated by a switch
sounds not good to me either.
I really do not see the big win. For the people who can write the complicated
sub queries that hive can not currently do there are usually smart enough to
look in the language manual and figure out a way to re-write the query.
> Build a full SQL-compliant parser for Hive
> ------------------------------------------
>
> Key: HIVE-3561
> URL: https://issues.apache.org/jira/browse/HIVE-3561
> Project: Hive
> Issue Type: Sub-task
> Components: Query Processor
> Affects Versions: 0.10.0
> Reporter: Shane Huang
>
> To build a full SQL compliant engine on Hive, we'll need a full SQL complant
> parser. The current Hive parser missed a lot of grammar units from standard
> SQL. To support full SQL there're possibly four approaches:
> 1.Extend the existing Hive parser to support full SQL constructs. We need to
> modify the current Hive.g and add any missing grammar units and resolve
> conflicts.
> 2.Reuse an existing open source SQL compliant parser and extend it to support
> Hive extensions. We may need to adapt Semantic Analyzers to the new AST
> structure.
> 3.Reuse an existing SQL compliant parser and make it co-exist with the
> existing Hive parser. Both parsers share the same CliDriver interface. Use a
> query mode configuration to switch the query mode between SQL and HQL (this
> is the approach we're now using in the 0.9.0 demo project)
> 4.Reuse an existing SQL compliant parser and make it co-exist with the
> existing Hive parser. Use a separate xxxCliDriver interface for standard SQL.
>
> Let's discuss which is the best approach.
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