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Greetings,
Here is the query that caused the server to use GROUP BY handler despite the mentioned handler type isn't used according to an execution plan:
SELECT SUM(L_EXTENDEDPRICE * (1 - L_DISCOUNT)) AS REVENUE FROM LINEITEM, PART WHERE ( P_PARTKEY = L_PARTKEY AND P_BRAND = 'Brand#41' AND P_CONTAINER IN ( 'SM CASE', 'SM BOX', 'SM PACK', 'SM PKG') AND L_QUANTITY >= 3 AND L_QUANTITY <= 3 + 1 AND P_SIZE BETWEEN 1 AND 5 AND L_SHIPMODE IN ('AIR', 'AIR REG') AND L_SHIPINSTRUCT = 'DELIVER IN PERSON' ) OR ( P_PARTKEY = L_PARTKEY AND P_BRAND = 'Brand#33' AND P_CONTAINER IN ( 'MED BAG', 'MED BOX', 'MED PKG', 'MED PACK') AND L_QUANTITY >= 14 AND L_QUANTITY <= 14 + 1 AND P_SIZE BETWEEN 1 AND 10 AND L_SHIPMODE IN ('AIR', 'AIR REG') AND L_SHIPINSTRUCT = 'DELIVER IN PERSON' ) OR ( P_PARTKEY = L_PARTKEY AND P_BRAND = 'Brand#45' AND P_CONTAINER IN ( 'LG CASE', 'LG BOX', 'LG PACK', 'LG PKG') AND L_QUANTITY >= 25 AND L_QUANTITY <= 25 + 1 AND P_SIZE BETWEEN 1 AND 15 AND L_SHIPMODE IN ('AIR', 'AIR REG') AND L_SHIPINSTRUCT = 'DELIVER IN PERSON' );
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Here is the execution plan:
MariaDB [tpch1c]> explain extended SELECT SUM(L_EXTENDEDPRICE * (1 - L_DISCOUNT)) AS REVENUE FROM LINEITEM, PART WHERE ( P_PARTKEY = L_PARTKEY AND P_BRAND = 'Brand#41' AND P_CONTAINER IN ( 'SM CASE', 'SM BOX', 'SM PACK', 'SM PKG') AND L_QUANTITY >= 3 AND L_QUANTITY <= 3 + 1 AND P_SIZE BETWEEN 1 AND 5 AND L_SHIPMODE IN ('AIR', 'AIR REG') AND L_SHIPINSTRUCT = 'DELIVER IN PERSON' ) OR ( P_PARTKEY = L_PARTKEY AND P_BRAND = 'Brand#33' AND P_CONTAINER IN ( 'MED BAG', 'MED BOX', 'MED PKG', 'MED PACK') AND L_QUANTITY >= 14 AND L_QUANTITY <= 14 + 1 AND P_SIZE BETWEEN 1 AND 10 AND L_SHIPMODE IN ('AIR', 'AIR REG') AND L_SHIPINSTRUCT = 'DELIVER IN PERSON' ) OR ( P_PARTKEY = L_PARTKEY AND P_BRAND = 'Brand#45' AND P_CONTAINER IN ( 'LG CASE', 'LG BOX', 'LG PACK', 'LG PKG') AND L_QUANTITY >= 25 AND L_QUANTITY <= 25 + 1 AND P_SIZE BETWEEN 1 AND 15 AND L_SHIPMODE IN ('AIR', 'AIR REG') AND L_SHIPINSTRUCT = 'DELIVER IN PERSON' );
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+------+-------------+----------+------+---------------+------+---------+------+------+----------+-----------------------------------------------------------------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+------+-------------+----------+------+---------------+------+---------+------+------+----------+-----------------------------------------------------------------------+
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| 1 | SIMPLE | LINEITEM | ALL | NULL | NULL | NULL | NULL | 2000 | 100.00 | Using where with pushed condition |
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| 1 | SIMPLE | PART | ALL | NULL | NULL | NULL | NULL | 2000 | 100.00 | Using where with pushed condition; Using join buffer (flat, BNL join) |
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+------+-------------+----------+------+---------------+------+---------+------+------+----------+-----------------------------------------------------------------------+
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2 rows in set, 2 warnings (0.90 sec)
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The issue could be reproduced only with server/columnstore engine built of:
develop branch columnstore fork of the server's code
develop branch columnstore engine
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