768fe43d3a
Previously, we were incrementing mentions one-by-one all concurrently in an unbounded fashion. This would cause a big spike in memory usage if there were an `@all` mention in a large channel. We fix this by changing the SQL query to take all userIDs at once. https://mattermost.atlassian.net/browse/MM-41752 ```release-note NONE ``` Co-authored-by: Mattermod <mattermod@users.noreply.github.com>