Re: Performance Problem Selecting "double" Filed

[Sergey Petrunya]

It's difficult to tell whether the performance can be increased as it depends on many factors, but

1) Selecting only the fields you need might increase performance as there will be less data to copy/send to the client. The actual gain will vary depending on where the bottleneck was.

2) Do you have any indexes on the table? If the table has an index that covers all the selected fields, MySQL might not perform full table scan but scan the index instead. In EXPLAIN it is displayed as "index" in "type" column (instead of "all" for full table scan).

If you need only a small fraction of table fields consider adding an index on that fields.

Sergey Petrunia, Software Developer
MySQL AB, www.mysql.com
My blog: http://s.petrunia.net/blog