Brendan, > Description: Â Â Â Âupdate does not honor order of subselect > > Details: > > SQL Update command does not follow the order of a WHERE field IN subselect. > > In the following code, I try to reset the order of rows in a column by > updating an order field. ÂUpdate does not honor the order of output form > the subselect.
This is by design. ORDER BY for anything but output is a PostgreSQL extension, which we support strictly so that subselects can use LIMIT. The SQL standard does not allow ORDER BY in subselects, and is pretty specific on query results not being ordered until the final execution step. Also, you should not count on subselect order in any subquery, because the subselect resultset may need to be re-ordered in order to join to the main query -- particularly since the PostgreSQL planner may re-write your query into a more efficient join type. If you need to update rows in a specific order, then write a script and use a loop. -- --Josh Josh Berkus Aglio Database Solutions San Francisco ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings
