[Info-Ingres] Combined stats on non key fields

[Martin Bowes]

Yep, tried that, same result.

 

Marty

 

From: Peter Gale [mailto:pgale61 at gmail.com] 
Sent: 01 October 2007 15:32
To: Martin Bowes
Subject: Re: [Info-Ingres] Combined stats on non key fields

 

Try chucking in -zu249 -zr249 for good measure. Inaccurate stats are
worse than no stats sometimes

On 01/10/2007, Martin Bowes < martin.bowes at ctsu.ox.ac.uk
<mailto:martin.bowes at ctsu.ox.ac.uk> > wrote:

Hi Peter,

 

Ah '-rindex_name' was one thing I didn't think of.

 

I just tried it, built the composite stats OK, but much to my amazement
it just made the join estimate worse! Its now saying one row not 120
rows! 

 

But it was a nice thought.

 

Marty

 

From: Peter Gale [mailto: pgale61 at gmail.com <mailto:pgale61 at gmail.com> ]

Sent: 01 October 2007 14:46
To: Martin Bowes
Cc: info-ingres at kettleriverconsulting.com
Subject: Re: [Info-Ingres] Combined stats on non key fields

 

Hi Marty,

You can generate a composite histogram on the columns of a secondary
index.

optimizedb -zcpk -rindex_name

I guess it is likely that you have a secondary on these columns if they
are being combine in restrictions alot. 

Peter Gale

On 01/10/2007, Martin Bowes <martin.bowes at ctsu.ox.ac.uk> wrote:

Hi Everyone,

 

Does anyone know if there are any plans to allow the generation of
combined stats on nominated non-key fields in a table? 

 

I have a query which has conisderable volatility in the plan generated
because of the assumption of no correlation between the attributes
involved in the queries where clause. This also results in a
consistently low join estimate which is leading to lock escalation. I
can demonstrate this very easily with trace point op189.

 

Martin Bowes

 

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-- 
Peter Gale
pgale61 at gmail.com 




-- 
Peter Gale
pgale61 at gmail.com 

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