[tarantool-patches] Re: [PATCH] Do not update schema_version on space:truncate().

Konstantin Osipov kostja at tarantool.org
Fri Jul 6 17:07:54 MSK 2018

* Serge Petrenko <sergepetrenko at tarantool.org> [18/07/06 14:52]:
> Schema version is used by both clients and internal modules to check
> whether there vere any updates in spaces and indices. While clients
> only need to be notified when there is a noticeable change, e.g.
> space is removed, internal components also need to be notified when
> something like space:truncate() happens, because even though this
> operation doesn't change space id or any of its indices, it creates a
> new space object, so all the pointers to the old object have to be updated.
> Currently both clients and internals share the same schema version, which
> leads to unnecessary updates on the client side.
> Fix this by implementing 2 separate counters for internal and public use:
> schema_state gets updated on every change, including recreation of the same
> space object, while schema_version is updated only when there are noticable
> changes for the clients. Introduce a new AlterOp to alter.cc to update
> public schema_version.
> Now all the internals reference schema_state, while all the clients use
> schema_version. box.iternal.schema_version() returns schema_version
> (the public one).

The new schema is instantiated/becomes effective in do(), not in commit. 

Before do() and commit() there is a yield and new queries
can see the new schema already.

Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov

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