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Date: Wed, 4 Dec 2019 15:03:37 +0300
From: Konstantin Osipov <kostja.osipov@gmail.com>
Message-ID: <20191204120337.GN6592@atlas>
References: <cover.1574277369.git.korablev@tarantool.org>
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In-Reply-To: <005fe990f2add1906bd106356a6c16efa4f027a3.1574277369.git.korablev@tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH v2 12/16] box: increment
	schema_version on ddl operations
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To: Nikita Pettik <korablev@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org, v.shpilevoy@tarantool.org

* Nikita Pettik <korablev@tarantool.org> [19/11/21 10:00]:
> Some DDL operations such as SQL trigger alter, check and foreign
> constraint alter don't result in schema version change. On the other
> hand, we are going to rely on schema version to determine expired
> prepared statements: for instance, if FK constraint has been created
> after DML statement preparation, the latter may ignore FK constraint
> (instead of proper "statement has expired" error). Let's fix it and
> account schema change on each DDL operation.

This is very crude:

- I can't imagine that changing a trigger affects any existing
  statement. It will have its own vdbe, and it doesn't change
  table schema. 

  Constraints need more thinking, but the idea is the same:
  not all schema changes are created equal.

- flushing entire cache on any such change is a huge inefficiency.
  It was not an issue before, but time has come to introduce
  per-object versioning, in addition to global versioning.

This is subject for future work.

So lgtm.


-- 
Konstantin Osipov, Moscow, Russia