Every phoenix_kit_* base table whose uuid column needs work.

Returns maps of %{name, type, nullable, has_pk}. A table is included when the column is the wrong type, is nullable, or the table has no primary key — the predicate the earlier guards should have used. column_exists?/3 is true for a character varying uuid, which is precisely why V40 skipped the table it was listed in.

Whether every non-null value in the column can be cast to uuid.

Checked BEFORE any DDL: ALTER … USING uuid::uuid aborts the surrounding transaction on the first malformed value, which in a migration means taking every other table's repair down with it.

Human-readable summary of what is wrong with one table, for logs and output.

Rows that de-duplication would DELETE, counted before any DDL runs.

The delete in repair_statements/4 is the only destructive step here, so both callers announce it rather than discovering it afterwards. lower(uuid::text) matches what the eventual cast to uuid collapses — two varchar rows differing only in case are one row after the rewrite — and works whatever the column's current type is.

Estimated row count, from the planner's statistics rather than a count(*).

A sequential scan to decide whether to avoid an expensive operation is self-defeating. reltuples of -1 means "never analyzed" and is reported as 0, so an un-analyzed table is repaired rather than skipped — being wrong in that direction leaves the table correct.

Whether this table's uuid column is not a proper primary key.

has_pk is "the table has a primary key", not "the primary key is on uuid". A table keyed on some other column is therefore reported healthy once its uuid column is typed and non-null, even though uuid is still not the key. Promoting it would mean dropping the existing key, which this migration will not do unasked; no table in the chain is in that shape (V74 removed the last of the legacy id keys), so the gap is recorded rather than coded around.

Fully-qualified, QUOTED table name.

The prefix is validated upstream, but the table name comes from the catalog and is interpolated into DDL. Quoting it means a legal-but-unusual identifier — a space, a capital, a reserved word — produces valid SQL rather than a syntax error that aborts the run. PostgreSQL escapes an embedded quote by doubling it.

The ordered SQL statements that repair one table.

Order is load-bearing and each step depends on the one before:

1. type — before anything is built on the column, so the index and the primary key are built on uuid, not on the varchar it replaces.
2. default — so rows inserted between here and the backfill get a value.
3. backfill — before SET NOT NULL, or the constraint aborts on exactly the NULLs it exists to prevent.
4. NOT NULL — before the primary key, which requires it.
5. de-duplicate — a table that has run without a key can hold duplicate uuids, and ADD PRIMARY KEY aborts on them. Rows sharing a uuid are the same logical row twice; ctid picks one deterministically.
6. primary key — last, once uniqueness and NOT NULL both hold.

concurrent_index: true splits the key into a CREATE UNIQUE INDEX CONCURRENTLY plus ADD PRIMARY KEY USING INDEX, which holds the exclusive lock only for the attach rather than the whole build, and drops any leftover index of that name first so an interrupted run is retryable. It cannot run inside a transaction, so it is available to the mix task and not to the migration.

Whether repairing this table requires rewriting it (a type change).