Visibility map arrives

Magnus Hagander's PostgreSQL blog

Wednesday, December 3. 2008

Posted by Magnus Hagander in PostgreSQL

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Visibility map arrives

Since Heikki doesn't have a blog of his own, I will take it upon myself to blog about this one: he has just committed the initial version of the visibility map feature for PostgreSQL 8.4.

In short, this means that VACUUM will now only need to visit pages in a table that has actually changed. So if you have a large table where only a very few rows change, VACUUM will require significantly less CPU and I/O to run. With this lower cost, it's also possible to run VACUUM more often on large tables - if nothing at all has changed, it's more or less a no-op!

In the future, the hope is to be able to build on this patch to implement things like index-only scans - but that's for another version.

Yet another great feature for 8.4 - this is shaping up to be a very good release I think.


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Visibility Map
Magnus benden önce bloglamış -- Visibility map PostgreSQL'e girdi. 8.4'e eklenen birçok yeni özellikten birisi. VACUUM işlemlerinin işlemci ve disk üzerine etkisini önemli oranda azaltacak ve belirgin şekilde başarım artışları sağlayacak bir özellik. T
Weblog: MadBlog
Tracked: Dec 04, 09:03
What's your favorite 8.4 feature?
Over the past month or so, I have been informally polling those of our customers I've been meeting with about which features in the upcoming 8.4 version of PostgreSQL they are most excited about, and most likely to have use for in the short-to-medium term
Weblog: Magnus Hagander's PostgreSQL blog
Tracked: Apr 14, 19:40

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This is the kind of advancements that justify the upgrade worth any adaptation work!
#1 Vincenzo Romano on 2008-12-03 15:11 (Reply)
This will be a great release, PostgreSQL will definitely have the most complete SQL dialect amongst opensource databases with CTE and Window Queries!
#2 pabloj on 2008-12-03 19:48 (Reply)

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No, there are no user defined functions in this. seq is the column name, then minus the o perator, then lag the bu [...]
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Yeah, unfortunately we are sti ll waiting on David to migrate the content over there.
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