Based on an initial review done, this is likely to be over a year of effort.

Discussion Topics for Tech Steering Committe:

• We will need to review to see where this falls in priority for this fiscal year, given that we are already oversubscribed.
• If we do prioritize, should we ideally look to finish anything of the list that has been started first, before we proceed with the recommended priority order, that way we have less WIP and open items.

January 19, 2022 Tech Steering Committee:

• Kate C.: team reviewed this request and Tim and Timo felt that this has performance implications so it is reasonable to support it, but estimated at least 1 year of effort.
• Ideal to prioritize list by quarter and start with the currently open items: https://docs.google.com/document/d/1oc0xbZ5L7xgK9o1jEg1SsAWO3lK4Z176Mz3VfeoNwxI/edit
• Mark B.: open to working this way and break down into chunks
• Kate C. - some migrations can take months and months to run, while others need active work

Action Items:

• Mark B.: will look at breaking down by quarter and closing open items, also triage by risk
• ask Tim and Amir to break-down

I was asked to break this down to work that can be done in a quarter. It depends on the number of people being put on this but I give it a try here:

Q3 (including some ongoing work)

• T275246: Populate rev_actor and rev_comment_id (ongoing, doesn't need human intervention, just making sure it's running, sometimes it needs restarts, etc.)
• T296380: flaggedtemplates table is still too big (ongoing, the same as above)
• T299417: Normalize templatelinks table (ongoing)
• T299691: Break down monster class: Database

Q4:

• {T299960}
• T299954: Write code for handing write and read of rev_comment_id
  • Migrating the rev_comment_id as well, that will take some time.
• Refactor and improve LB/LBFactory code quality (TODO: hash out the details)
• T299691: Break down monster class: Database (continue)

Q1:

• T299947: Normalize pagelinks table
• T233004: Update CheckUser for actor and comment table
• T311866: Migrate Database::select usages to SelectQueryBuilder (in WMF-deployed extensions)

Q2:

• T241053: Normalize globalimagelinks table
• T20493: RFC: Unify the various deletion systems (start)
• Merge Mysqli class into Mysql

Q3:

• T20493: RFC: Unify the various deletion systems (continue)
• T183490: MCR schema migration stage 4: Migrate External Store URLs (wmf production)
• T299953: Normalize imagelinks table
• Build new types of Query Builder (currently QB only supports SELECT)

Q4:

• T299951: Normalize categorylinks table
• rev_id and rc_id to bigint: T63111: Convert primary key integers and references thereto from int to bigint (unsigned)
• T28741: Migrate file tables to a modern layout (image/oldimage; file/file_revision; add primary keys)

This is very rough and ofc will change according to new stuff coming up.

Another way of seeing it is through lens of three value mini-streams: revision metadata, links normalization, rdbms code quality.

In T299691#8135071, @Krinkle wrote:

A summary of some of the work so far:

Two major classes have been split out from IDatabase by @Ladsgroup over the past few months:

• TransactionManager, T307616: Move SQL building code from Database class to SQLPlatform
• SQLPlatform: T299691: Break down monster class: Database

This in addition to removing (not moving) various methods such as:

• T255493: Consider phasing out ILoadBalancer::getLazyConnectionRef in favour of ILoadBalancer::getConnectionRef
• T286694: Drop legacy cruft arising from introduction of ResultWrapper
• T296960: Remove unused or barely used functions of IDatabase
• T299392: Remove unused or barely used functions of ILoadBalancer and ILBFactory