Details
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Improvement
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Status: Closed
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Major
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Resolution: Fixed
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4.0.0
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None
Description
A query involve a Hive UDF which produce a constant value does not push to JDBC table. Replacing the UDF with a constant push down works. Ideally, Hive shall first do constant folding and then push the computation.
Here is the example:
explain select PRINCIPAL_NAME from sys.TBL_PRIVS where PRINCIPAL_NAME=current_user(); +----------------------------------------------------+ | Explain | +----------------------------------------------------+ | Plan optimized by CBO. | | | | Stage-0 | | Fetch Operator | | limit:-1 | | Select Operator [SEL_3] | | Output:["_col0"] | | Filter Operator [FIL_2] | | predicate:(_col5 = 'hrt_qa') | | Select Operator [SEL_1] | | Output:["_col5"] | | TableScan [TS_0] | | Output:["principal_name"],properties:{"hive.sql.query":"SELECT `tbl_grant_id`, `create_time`, `grant_option`, `grantor`, `grantor_type`, `principal_name`, `principal_type`, `tbl_priv`, `tbl_id`, `authorizer`\nFROM `TBL_PRIVS`","hive.sql.query.fieldNames":"tbl_grant_id,create_time,grant_option,grantor,grantor_type,principal_name,principal_type,tbl_priv,tbl_id,authorizer","hive.sql.query.fieldTypes":"bigint,int,int,string,string,string,string,string,bigint,string","hive.sql.query.split":"true"} | | | +----------------------------------------------------+
If I replace current_user() with a constant, the predicate is pushed to table scan.
Also, setting annotation deterministic=true and make initialize() return a ConstantObjectInspector of GenericUDFCurrentUser does not make a difference.
Attachments
Attachments
Issue Links
- is related to
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HIVE-27291 Constant reduction in CBO does not work for UNIX_TIMESTAMP
- Open