mysql - Most efficient indexes to use for a query using WHERE and GROUP BY? -

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mysql - Most efficient indexes to use for a query using WHERE and GROUP BY? -

i have table ~7 1000000 rows continually running queries of sort:

select myfield, count(*) mytable myfield2='constantvalue' , myfield not in ( select field anothertable) , timestamp >= [arbitrarytimestamp] grouping myfield;

cardinalities above fields:

myfield = 40,000 distinct values. timestamp = distinct, around 7 1000000 distinct values. myfield2 = 2 distinct values. field anothertable = 50 distinct values.

as expected, runs terribly slow, , using explain tells me using where; using temporary; using filesort.

i improve efficiency of these queries adding index table, i'm not sure best way is.

should add together index on myfield? , index on timestamp? both? combined index on both?

also, there else can speed these type of queries?

in add-on suggestions mike , dkamins, having sub-query might bottleneck. restructure left bring together , apply based on null (ensure "anothertable" has index on "field" join

select myfield, count(*) mytable left bring together anothertable on mytable.myfield = anothertable.field myfield2='constantvalue' , anothertable.field null , timestamp >= [arbitrarytimestamp] grouping myfield;

i have index based on (myfield2, timestamp, myfield). myfield2 specific qualifier, don't bother including other crud within focus... that, looking @ specific timeframe... that, having myfield help optimize groupby. first 2 parts of key/where, used filter criteria, rest remain in proper order grouping.

mysql sql optimization indexing query-optimization

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