I have a table which I do mainly updates and I’m wondering if update queries would benefit from having an index on the where column and the updated column or an index on just where column?
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I have a table which I do mainly updates and I’m wondering if update queries would benefit from having an index on the where column and the updated column or an index on just where column?
Just on the where column. An index on the update column will actually slow down your query because the index has to be updated along with the data. An index on the where column will speed up updates, and selects, but slow down some insertions.
Indices also cause overhead when you delete rows. In general they are a good thing though on columns you are using
WHEREon a lot, and they are basically necessary on columns you do joins on, orORDER BY