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Grouped Index Tuples

From: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Grouped Index Tuples
Date: 2007-02-22 12:47:42
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Lists: pgsql-hackers
I've brought the GIT patch up-to-date with CVS head. The latest version 
can be found at

I also reran the CPU bound test cases with the latest patch.

I want this in 8.3 in some form, and I have the time to do any required 
changes. If someone wants to see more tests, I can arrange that as well.

The patch is pretty big at the moment. I think the best way to proceed 
with this is to extract some smaller, incremental patches from it that 
just refactor the current b-tree code. After that, the final patch that 
implements GIT should be much smaller and more readable. And there's 
still a bunch of todo items there as well...

But before I start doing that, I need some review and general agreement 
on the design. What I don't want to happen is that three days after the 
feature freeze, someone finally looks at it and finds a major issue or 
just thinks it's an unreadable mess, and we no longer have the time to 
fix it.

One question that I'm sure someone will ask is do we need this if we 
have bitmap indexes? Both aim at having a smaller index, after all. The 
use cases are quite different; GIT is effective whenever you have a 
table that's reasonably well-clustered. Unlike the bitmap indexam, GIT's 
effectiveness doesn't depend on the number of distinct values, in 
particular it works well with unique indexes. GIT is comparable to 
clustered indexes in other DBMSs (in fact we might want to call GIT that 
in the end).

   Heikki Linnakangas


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