This is a followup to T153182: now that the updated code is deployed so all inserts specify a value for this column, we can drop the unwanted default. No work is blocked on this, so not setting Schema-change-in-production.
This should be able to be done with ALGORITHM=INPLACE, LOCK=NONE and shouldn't require a table rebuild, per https://dev.mysql.com/doc/refman/5.6/en/innodb-create-index-overview.html#online-ddl-column-operations.
From the checklist at https://wikitech.wikimedia.org/wiki/Schema_changes:
- ALTERs to run: https://gerrit.wikimedia.org/r/c/mediawiki/core/+/322728/8/maintenance/archives/patch-externallinks-el_index_60-drop-default.sql
- Where to run those changes: all.dblist
- When to run those changes: No time constraint.
- If the schema change is backwards compatible: Yes.
- If the schema change has been tested already on some of the test/beta wikis: It has been auto-deployed to Beta since 15 May, I believe.
- if the data should be made available on the labs replicas and/or dumps: N/A
Schema change progress:
- s1
- codfw
- eqiad progress T197891#4407014
- s2
- codfw
- eqiad progress T197891#4403310
- s3
- codfw
- eqiad progress T197891#4414815
- s4
- codfw
- eqiad progress T197891#4408159
- s5
- codfw
- eqiad progress T197891#4398631
- s6
- codfw
- eqiad progress T197891#4402329
- s7
- codfw
- eqiad progress T197891#4410831
- s8
- codfw
- eqiad progress T197891#4410664