On May 22, 2007, at 6:17 PM, Mike Orr wrote:
> > Regarding the slowness I was experiencing mapping a select (which > caused a nested SELECT in the SQL), I converted the inner select to a > MySQL VIEW and the speed improved dramatically. The MySQL manual says > it manages a select against a view by merging them into a single > select if it can, but it doesn't seem to do that with nested selects. > > "EXPLAIN SELECT ... FROM the_view WHERE ..." > shows it's actually selecting from the underlying table (i.e., it > lists the real table name), while eanwhile, > "EXPLAIN SELECT ... FROM (SELECT ... FROM the_table) AS my_alias > WHERE ..." > does two selects rather than merging the SQL into one. > well thats pretty awful. an argument to map against the table directly instead of a select. we do have some new ways to get additional columns into a mapping now without it needing to encapsulate it (column_property(), add_column(), query.select (someselect())), so mapping to selects is not quite as necessary. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
