[tarantool-patches] Re: [PATCH 1/8] vinyl: move update optimization from write iterator to tx

Konstantin Osipov kostja at tarantool.org
Tue Oct 23 10:35:56 MSK 2018

* Vladimir Davydov <vdavydov.dev at gmail.com> [18/10/15 10:15]:
> An UPDATE operation is written as DELETE + REPLACE to secondary indexes.
> We write those statements to the memory level even if the UPDATE doesn't
> actually update columns indexed by a secondary key. We filter them out
> in the write iterator when the memory level is dumped. That's what we
> use vy_stmt_column_mask for.
> Actually, there's no point to keep those statements until dump - we
> could as well filter them out when the transaction is committed. This
> would even save some memory. This wouldn't hurt read operations, because
> point lookup doesn't work for secondary indexes by design and so we have
> to read all sources, including disk, on every read from a secondary
> index.
> That said, let's move update optimization from the write iterator to
> vy_tx_commit. This is a step towards removing vy_stmt_column_mask.

OK to push.

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

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