A concurrent build that is still running is INVALID with its migration not
yet finished, exactly like a failed one. With the web and worker roles in
two containers, the second boot dropped the index the first was building,
which cancelled the first one's migration and left it failed until someone
resolved it by hand.
The check and the drop now run in one transaction that first takes Prisma's
migration lock without waiting and does nothing when another instance holds
it; an index Postgres reports as being built is never dropped. One
transaction also keeps lock_timeout on the statement it bounds behind a
transaction pooler, and the applied-migrations lookup quotes the schema, so
a mixed-case schema no longer reads as having none applied.
A CREATE INDEX CONCURRENTLY that fails half-way leaves an INVALID index,
and the migration re-run after migrate resolve --rolled-back finds it
through IF NOT EXISTS and does nothing: recorded applied, with an index
the planner never uses. 0477 has this shape.
The boot now drops an INVALID index that a not-yet-applied migration
builds concurrently before it runs migrate deploy, with a bounded lock
wait, so the re-run builds it again. An INVALID index whose migration is
recorded applied is named on stderr with the rebuild that mends it. The
deploy runbook says both.
Marc-André Bombeck