0
votes
2answers
42 views

Why search by date field requires engine to touch all records?

Why search by date field requires engine to touch all records? Is there any way to avoid it? Following query EXPLAIN select * FROM playdays where realdate>=Date('2010,01,01') ; shows that ...
0
votes
2answers
239 views

Is there any manual for the visual explain in mysql? The output plan is unreadable

Just like this example, I cannot even tell the join ordering from it. And what does "ALL" and "ref" in the table mean? Is there any manual about the visual explain?
2
votes
1answer
184 views

Query results in a strange explain output

So I have a medium sized query that hits 15 tables. The query takes 36 sec on MySQL to complete. I ran EXPLAIN on the query and one of the tables returned this. '1', 'SIMPLE', 'mount_adapters', ...