hello,
i have a couple of questions about my SQL query.
1. if i want all rows in table 1 that may or may not have a counterpart
row in table 2, i use LEFT JOIN. this is HORRIBLY slow! why? if i make it
a simple join (i.e., without the words "LEFT JOIN") then it is a little
faster.
2. secondly, i need to have an OR in my join clause.
where
(table1.col1 = table2.col1 or table1.col2 = table2.col1)
this is for a search procedure. if i remove the OR, it is much faster.
how can i get around this? i need to have the OR because of the search
engine in the website, but i need it to be fast.
3. based on the OR condition, what kind of indices can i use?
thanks/erick
mysql, sql, query
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