防止全表扫描简单查询

Question

Lately we been having a lot of problems with our mysql server i have been running some test with a profiler (JetProfiler) and a stresstester (loadUI). I have noticed that after having atleast 20 connections run with loudUI at same time it already makes it unable to connect or connect REALLY slow to the webpage. Jetprofiler says that prety much every query we run is bad since they all use full table scans, I'm wondering if this could actually be the problem.

Here's a screenshot of a query that probably gets run the most:

how would I improve this?

Answer 1

Just create single indices for following columns: datum, webid, and actief:

create index idx_datum on nieuws(datum);
create index idx_webid on nieuws(webid);
create index idx_actief on nieuws(actief);

This should yield in a better performance of this query.