Help speed this MySQL query which is taking too long because of an aggregate function
I am using a following query in MySQL for fetching data from a table. Its taking too long because the conditional check within the aggregate function.Please help how to make it faster
SELECT testcharfield
, SUM(IF (Type = 'pi',quantity, 0)) AS OB
, SUM(IF (Type开发者_如何学JAVA = 'pe',quantity, 0)) AS CB
FROM Table1
WHERE sequenceID = 6107
GROUP BY testcharfield
If you don't care about records that don't have either of those types, you should get better performance this way:
SELECT testcharfield,
SUM(IF (Type = 'pi', quantity, 0)) AS OB,
SUM(IF (Type = 'pe', quantity, 0)) AS CB
FROM Table1
WHERE Type in ('pi', 'pe')
and sequenceID = 6107
GROUP BY testcharfield
If you don't already have them, consider indexes on testcharfield
and testcharfield
. I am guessing the cardinality of the Type
column would not make it a good candidate for an index, but consider that as well.
SELECT testcharfield, MAX(OB) AS OB, MAX(CB) AS CB FROM
((SELECT testcharfield, SUM(quantity) AS OB, 0 AS CB
FROM Table1
WHERE Type = 'pi' AND sequenceID = 6107
GROUP BY testcharfield)
UNION
(SELECT testcharfield, 0 AS OB, SUM(quantity) AS CB
FROM Table1
WHERE Type = 'pe' AND sequenceID = 6107
GROUP BY testcharfield))
Check your indexes on testcharfield, sequenceID, and Type.
Have you tried getting the totals first and then creating the crosstab columns:
Select Z.testcharfield
, Sum( Case When Z.Type = 'pi' Then Total End ) As OB
, Sum( Case When Z.Type = 'pe' Then Total End ) As CB
From (
Select testcharfield
, SUM(quantity) AS Total
From Table1
Where sequenceID = 6107
And Type In('pi','pe')
Group By testcharfield, Type
) Z
Group By Z.testcharfield
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