tarantool / tarantool / 12051236024

87%

Build Type

push

github

Committed by locker

Commit Message

vinyl: skip invisible read sources

A Vinyl read iterator scans all read sources (memory and disk levels)
even if it's executed in a read view from which most of the sources are
invisible. As a result, a long running scanning request may spend most
of the time skipping invisible statements. The situation is exacerbated
if the instance is experiencing a heavy write load because it would pile
up old statement versions in memory and force the iterator to skip over
them after each disk read.

Since the replica join procedure in Vinyl uses a read view iterator
under the hood, the issue is responsible for a severe performance
degradation of the master instance and the overall join procedure
slowdown when a new replica is joined to an instance running under
a heavy write load.

Let's fix this issue by making a read iterator skip read sources that
aren't visible from its read view.

Closes #10846

NO_DOC=bug fix

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