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From: Kirill Reshke <reshkekirill@gmail.com>
Date: Tue, 20 Aug 2024 11:09:49 +0500
Message-ID: <CALdSSPhzzJffBEDaihtT5jXpq_aF++wX2BfJhZkrnqn-E0S_LQ@mail.gmail.com>
Subject: Re: Incremental View Maintenance, take 2
To: Yugo NAGATA <nagata@sraoss.co.jp>
Cc: Peter Smith <smithpb2250@gmail.com>, jian he <jian.universality@gmail.com>, 
	Tatsuo Ishii <ishii@sraoss.co.jp>, pgsql-hackers@postgresql.org
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On Tue, 20 Aug 2024 at 02:14, Kirill Reshke <reshkekirill@gmail.com> wrote:

> == Other thoughts
>
> In OLAP databases (see [2]), IVM opens the door for 'view
> exploitation' feature. That is, use IVM (which is always up-to-date)
> for query execution. But current IVM implementation is not compatible
> with Cloudberry Append-optimized Table Access Method. The problem is
> the 'table_tuple_fetch_row_version' call, which is used by
> ivm_visible_in_prestate to check tuple visibility within a snapshot. I
> am trying to solve this somehow. My current idea is the following:
> multiple base table modification via single statement along with tuple
> deletion from base tables are features. We can error-out these cases
> (at M.V. creation time) all for some TAMs, and support only insert &
> truncate. However, I don't know how to check if TAM supports
> 'tuple_fetch_row_version' other than calling it and receiving
> ERROR[3].
>

I reread this and I find this a little bit unclear. What I'm proposing
here is specifying the type of operations IVM supports on creation
time. So, one can run

CREATE IVM immv1 WITH (support_deletion = true/false,
support_multiple_relation_change = true/false). Then, in the query
execution time, we just ERROR if the query leads to deletion from IVM
and support_deletion if false.


-- 
Best regards,
Kirill Reshke