Bug 2488 - SQL: dynamic selectivity optimiser required
Summary: SQL: dynamic selectivity optimiser required
Status: NEW
Alias: None
Product: SQL
Classification: Unclassified
Component: all (show other bugs)
Version: -- development
Hardware: x86 (i?86) Linux
: --- enhancement
Assignee: SQL devs
URL: http://sourceforge.net/support/tracke...
Depends on:
Reported: 2009-03-22 08:42 CET by Stefan de Konink
Modified: 2016-04-11 11:46 CEST (History)
0 users


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Description Stefan de Konink 2009-03-22 20:42:21 CET
Using the OSM dataset I noticed there is a significant difference in the following queries:

select * from way_tags where way = 9168360 and k = 'created_by';
Timer   10583.483 msec 2 rows


select * from way_tags where k = 'created_by' and  way = 9168360;
Timer     331.086 msec 2 rows

(this is not about hot/cold performance, the next try of the first query results in 10286.816 msec)

Niels noted that this could be solved automatically using a dynamic selectivity optimiser. I first noticed this issue using delete from.
Comment 1 Martin Kersten cwiconfidential 2009-03-22 20:51:23 CET
such an optimizer is a feature request, rather then a bug.
Comment 2 Pseudo user for Sourceforge import 2010-05-04 09:32:09 CEST
This bug was previously known as tracker item 2704025 at http://sourceforge.net/support/tracker.php?aid=2704025