On 15/09/2017 12:51, Daniel Kinzler wrote:
I'm working on the database schema for Multi-Content-Revisions (MCR)
<https://www.mediawiki.org/wiki/Multi-Content_Revisions/Database_Schema> and
I'd
like to get rid of the rev_sha1 field:
Maintaining revision hashes (the rev_sha1 field) is expensive, and becomes more
expensive with MCR. With multiple content objects per revision, we need to track
the hash for each slot, and then re-calculate the sha1 for each revision.
<snip>
Hello,
That was introduced by Aaron Schulz. The purpose is to have them pre
computed since that is quite expensive to have to do it on million of rows.
A use case was to easily detect reverts.
See for reference:
https://phabricator.wikimedia.org/T23860
https://phabricator.wikimedia.org/T27312
I guess Aaron Halfaker, Brion Vibber, Aaron Schulz would have some
insights about it.
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