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Serious Serious
Reported By: Wolfgang Klein
Reported On: 2/16/2017
For: Version 2.24 Build 3
# 4493 Partial-Comparison LIKE Conditions in WHERE Clause Not Optimized Properly

I'm experiencing a performance issue with ElevateDB 2.24 build 3.

The following query takes 16s to execute, a query with just one of the "and" operands take less than 1s. I would expect that all three queries take <1s.

Original:

select IDNR from "IWMMText" where ("MMNR" like 'l%') and ("Text" like '1%')

Variations:

select IDNR from "IWMMText" where ("MMNR" like 'l%')                        -> <1s
select IDNR from "IWMMText" where                        ("Text" like '1%') -> <1s



Comments Comments
The bug was in the partial-length (LIKE) row count estimates. They were being estimated way too low because the high end of the key wasn't being examined properly.


Resolution Resolution
Fixed Problem on 2/17/2017 in version 2.25 build 1


Products Affected Products Affected
ElevateDB Additional Software and Utilities
ElevateDB DAC Client-Server
ElevateDB DAC Client-Server with Source
ElevateDB DAC Standard
ElevateDB DAC Standard with Source
ElevateDB DAC Trial
ElevateDB LCL Standard with Source
ElevateDB PHP Standard
ElevateDB PHP Standard with Source
ElevateDB PHP Trial
ElevateDB VCL Client-Server
ElevateDB VCL Client-Server with Source
ElevateDB VCL Standard
ElevateDB VCL Standard with Source
ElevateDB VCL Trial

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