does this "top-200" query do a table scan
I have a table "Article_t" with two particular columns:
"id_c" and progressMade_c", both of which are configured as "bigint"
id_c is the primarykey
progressMade_c is always initially zero, but when work begins on a row, it is updated to be the current timestamp in millis, until finally done, when it becomes the maximum positive value.
Aside from the primary key index, I have an index on (progressMade_c, id_c)
The basic idea is that I want an efficient query that not only fetches virgin (unworked on records) but also records whose "munging" failed to finish in a reasonable amount of time.
Does this query do a table scan, or if so, at least a very efficient one?
select id_c from Article_t where progressMade_c < :maxvalue limit 200
where :maxvalue is set to some parameter equal to the current timestamp minus 10 minutes?
Basically this is a "top-200" query of articles to work on, with the idea being that I want the minimum id values to be returned.
Andy
(InnoDB)
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does this "top-200" query do a table scan
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