mysql - Optimizing a SQL query to avoid full table scan -


consider following query:

select * transactions day(stamp - interval 3 hour) = 1;

the stamp column in transactions table timestamp , there index on it. how change query avoids full table scans? (that is, using stamp outside of day() function)

thanks!

this how it:

add fields: year, month, day or hour, minute depending on traffic expect. build trigger populate fields, maybe subtracting 3 hour interval in advance. build index on fields.


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