Re: Measuring the Query Optimizer Effect: Turning off the QO? - Mailing list pgsql-general

From Rob Sargent
Subject Re: Measuring the Query Optimizer Effect: Turning off the QO?
Date
Msg-id 6E1859C3-4453-4AC2-ABE9-C4F40E5CCDC0@gmail.com
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In response to Measuring the Query Optimizer Effect: Turning off the QO?  (Tom Mercha <mercha_t@hotmail.com>)
Responses Re: Measuring the Query Optimizer Effect: Turning off the QO?
List pgsql-general

> On Jul 7, 2019, at 5:22 PM, Tom Mercha <mercha_t@hotmail.com> wrote:
> 
> Hi All
> 
> As we know, a query goes through number of stages before it is executed. 
> One of these stages is query optimization (QO).
> 
> There are various parameters to try and influence optimizer decisions 
> and costs. But I wanted to measure the effect of such a stage by turning 
> it off completely and I can't find such a parameter which explicitly 
> does that. Then I could execute a query to get the effect of "QO active 
> and "QO inactive" and compare.
> 
> Obviously, I know well what the results would generally look like but I 
> am just interested in measuring the differences for various types of 
> queries. I am also aware that this is a simple comparison - there are 
> more interesting comparisons to perform with QO tweaks, but right now I 
> am interested in something basic.
> 
> So how would one shut down QO? Or at least, obtaining the guarantee of 
> generating the worst plan possible, ideally without touching many 
> parameters?
> 
> Best,
> Tom

Drop all indices?




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