Re: Slow update with two like 'string%' conditions

[Øystein Grøvlen]

Hi Oleg,

This query could be much more performant if you could rely on exact matching of symbol and/or name instead of partial matching. The way it is now, all records
in final table with fdate between q.namedt and q.nameendd will have to be checked for every row of crsp_stocknames table. If exact matching could be done, a multi-column index on (symbol, name, datef) would be able to limit the number of rows to
be inspected significantly.

The way it is now, I do not on top of my head see any way to get this query to perform better.

Øystein Grøvlen,
Senior Principal Software Engineer,
MySQL Group, Oracle,
Trondheim, Norway