Mostafa Mokhtar created IMPALA-7020:
---------------------------------------
Summary: Order by expressions in Analytical functions are not
materialized causing severe slow down
Key: IMPALA-7020
URL: https://issues.apache.org/jira/browse/IMPALA-7020
Project: IMPALA
Issue Type: Bug
Components: Frontend
Affects Versions: Impala 2.12.0
Reporter: Mostafa Mokhtar
Attachments: Slow case profile.txt, Workaround profile.txt
Order by expressions in Analytical functions are not materialized and cause
queries to run much slower.
The rewrite for the query below is 20x faster, profiles attached.
Repro
{code}
select *
FROM
(
SELECT
o.*,
ROW_NUMBER() OVER(ORDER BY evt_ts DESC) AS rn
FROM
(
SELECT
l_orderkey,l_partkey,l_linenumber,l_quantity, cast (l_shipdate as
string) evt_ts
FROM
lineitem
WHERE
l_shipdate BETWEEN '1992-01-01 00:00:00' AND '1992-01-15 00:00:00'
) o
) r
WHERE
rn BETWEEN 1 AND 101
ORDER BY rn;
{code}
Workaround
{code}
select *
FROM
(
SELECT
o.*,
ROW_NUMBER() OVER(ORDER BY evt_ts DESC) AS rn
FROM
(
SELECT
l_orderkey,l_partkey,l_linenumber,l_quantity, cast (l_shipdate as
string) evt_ts
FROM
lineitem
WHERE
l_shipdate BETWEEN '1992-01-01 00:00:00' AND '1992-01-15 00:00:00'
union all
SELECT
l_orderkey,l_partkey,l_linenumber,l_quantity, cast (l_shipdate as
string) evt_ts
FROM
lineitem limit 0
) o
) r
WHERE
rn BETWEEN 1 AND 101
ORDER BY rn;
{code}
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