chiprivers Posted September 25, 2010 Share Posted September 25, 2010 Other than applying a primary index to my id column, I have not used indexes in my tables before. After reading an article on top tips for mysql basics, I understand that it is best to apply an index to any column on which you will be searching on regularly. I have several tables from which I extract data from using JOINs in my queries. Do I need to apply an index to both columns used within the JOIN or just, say the right table on a LEFT JOIN? ie. table1 has a column 'table2Ref' and table 2 has column 'id'. SELECT * FROM table1 LEFT JOIN table2 ON table1.table2Ref = table2.id The id column in table2 will already have a primary index on it, but should I apply an index to the table2Ref column in table1? Quote Link to comment https://forums.phpfreaks.com/topic/214358-indexes/ Share on other sites More sharing options...
fenway Posted September 25, 2010 Share Posted September 25, 2010 Only on the "right" table of any join. Quote Link to comment https://forums.phpfreaks.com/topic/214358-indexes/#findComment-1115612 Share on other sites More sharing options...
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