It depends what you need and how your data looks.
Say you have a table with 4 columns:
col1 has 1000 dictinct values
col2 has 1 dictinct values
col3 has 100 dictinct values
col4 has 10 dictinct values
In this case:
select col1,col2 from tbl where col1=... and col2=...
Having a single
Hi,
up to now my idea of how MySQL uses indexes was, that when I have a WHERE
clause with several fields and I have an index on each field, MySQL chooses
one index (from which it thinks that it will return the fewest rows when
matched again the condition) and uses this index to "select" a couple o
