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From Pengcheng Xiong <pxi...@apache.org>
Subject [DISCUSSION] Deprecate HIVE_SUPPORT_SQL11_RESERVED_KEYWORDS
Date Sat, 01 Oct 2016 03:52:40 GMT
Hi all,

    I logged HIVE-14872 <https://issues.apache.org/jira/browse/HIVE-14872> to
deprecate the configuration of HIVE_SUPPORT_SQL11_RESERVED_KEYWORDS. The
main purpose for the configuration of HIVE_SUPPORT_SQL11_RESERVED_KEYWORDS
is for backward compatibility (See HIVE-6617) because a lot of reserved key
words have been used as identifiers in the previous releases. We already
have had several releases with this configuration.

    Now when I tried to add new set operators to the parser, ANTLR is
always complaining "code too large". I think it is time to remove this
configuration. (1) It will simplify the parser logic and largely reduce the
size of generated parser code; (2) it leave space for new features,
especially those which require parser changes.

    Here is summary of current parser code size

422345  HiveLexer.java
2436601  HiveParser.java
814184  HiveParser_FromClauseParser.java
2705920  HiveParser_IdentifiersParser.java
777665 HiveParser_SelectClauseParser.java

    After change, it will become

422345 HiveLexer.java
2253691 HiveParser.java
506224 HiveParser_FromClauseParser.java
2108342 HiveParser_IdentifiersParser.java
363665 HiveParser_SelectClauseParser.java

    Thanks.

Best
Pengcheng

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