Michael Haeusler created HIVE-12898:
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Summary: Hive should support ORC block skipping on nested fields
Key: HIVE-12898
URL: https://issues.apache.org/jira/browse/HIVE-12898
Project: Hive
Issue Type: Improvement
Components: ORC
Affects Versions: 1.2.1, 0.14.0
Reporter: Michael Haeusler
Hive supports predicate pushdown (block skipping) for ORC tables only on
top-level fields. Hive should also support block skipping on nested fields
(within structs).
Example top-level: the following query selects 0 rows, using a predicate on
top-level column foo. We also see 0 INPUT_RECORDS in the summary:
{code:sql}
SET hive.tez.exec.print.summary=true;
CREATE TABLE t_toplevel STORED AS ORC AS SELECT 23 AS foo;
SELECT * FROM t_toplevel WHERE foo=42 ORDER BY foo;
[...]
VERTICES TOTAL_TASKS FAILED_ATTEMPTS KILLED_TASKS DURATION_SECONDS
CPU_TIME_MILLIS GC_TIME_MILLIS INPUT_RECORDS OUTPUT_RECORDS
Map 1 1 0 0 1.22
2,640 102 0 0
{code}
Example nested: the following query also selects 0 rows, but using a predicate
on nested column foo.bar. Unfortunately we see 1 INPUT_RECORDS in the summary:
{code:sql}
SET hive.tez.exec.print.summary=true;
CREATE TABLE t_nested STORED AS ORC AS SELECT NAMED_STRUCT('bar', 23) AS foo;
SELECT * FROM t_nested WHERE foo.bar=42 ORDER BY foo;
[...]
VERTICES TOTAL_TASKS FAILED_ATTEMPTS KILLED_TASKS DURATION_SECONDS
CPU_TIME_MILLIS GC_TIME_MILLIS INPUT_RECORDS OUTPUT_RECORDS
Map 1 1 0 0 3.66
5,210 68 1 0
{code}
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