RE: incremental statistics and histograms
Date: Mon, 16 Nov 2020 18:47:14 +0000
Message-ID: <24321_1605552454_5FB2C946_24321_19008_1_28681226d2a146a0a0c8e520c76275a4_at_vontobel.com>
Hi Chinar,
Thanks for the link to your article
Our situation is as follows: an application job gathers all stale and empty statistics several times in the night after the loads. Other processing is waiting on the statistics to finish.
In the meantime, I figured out that most probably only stale statistics of the current (month) partitions are critical.
So I proposed the following to the application to test:
- Lock statistics of large tables which would take longer if synopses have to be recalculated.
- Gather only current partition (granularity = partition) statistics immediately after the load if stale.
- Asynchronously (i.e., nobody has to wait) gather global statistics of the locked tables once they become stale
A little disadvantage is that the creation of new histograms is delayed until global statistics become stale, but I don’t think that’s a problem. Due to linear decay the cardinality estimates shouldn’t be devastating even if predicates are a little bit out of min/max range.
Best regards,
Nenad
https://nenadnoveljic.com/blog
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