Jesus Camacho Rodriguez created HIVE-21388:
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Summary: Constant UDF is not pushed to JDBCStorage Handler
Key: HIVE-21388
URL: https://issues.apache.org/jira/browse/HIVE-21388
Project: Hive
Issue Type: Improvement
Components: CBO, StorageHandler
Affects Versions: 4.0.0
Reporter: Daniel Dai
Assignee: Jesus Camacho Rodriguez
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:
{code}
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"}
|
| |
+----------------------------------------------------+
{code}
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.
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