* MM-39351: fixes LastRootPostAt being null
After upgrading to v6.1 there is a chance for LastRootPostAt to be NULL.
This might be due to a faulty migration when upgrading to v5.35.
v5.35 had `create_msg_root_count` where LastRootPostAt was used as a
temporary column which at the end was deleted.
Then on v6.1 we are adding that column again, this time to keep.
If the migration to v5.35 had failed and it didn't drop the column
the `upgrade_cte` (v6.1) migration would leave some channels with `LastRootPostAt`
being NULL.
This resulted in crashing the app.
This commit fixes that by running again a migration to again set
LastRootPostAt only when it's NULL this time and then set it to 0
for channels that might still have LastRootPostAt being NULL
(channels with no posts).
PS: the whole issue arose when upon creating the `upgrade_cte` migration
the create_msg_root_count migration was manually edited to change
the column name from LastRootPostAt to LastRootAt.
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
* migrations: add if statements for some queries
* add better checks to upgrade posts v6 migration
* use "is null" instead of "= null"
* fix down script for users v6
* reflect review comments
* Create basic make commands for configuring golang-migrate
* Showcase full flow with new migrations
* Apply PR suggestions
* Migrate over team members
* Update mocks
* Fix specs
* Move columns that added after table creation onto separate stmts
* Put back gorp table definitions
* Fix issues with golang-migrate that not tracks underlying db driver
* Help prompt after new migration and consistent checksum for bindata
* Put gorp mapping back
* Apply PR suggestiong
* Close migrations after they run
* Add migration file to bindata check
* Updates needed
* Reset store_test
* Add copyright
* Apply PR suggestions
* Fix new circleci check
* Put back upgrade step for backwards comp
* Add store test to test migration directions
* Apply PR suggestions
* Add go-bindata to tools
* Apply PR suggestios
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
