Tolerate existing unique_states column in 006 migration

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Dropped internal random generators in favor of `math/rand/v2`, which will have the effect of making code fully incompatible with Go 1.21 (`go.mod` has specified a minimum of 1.22 for some time already though). [PR #691](https://github.com/riverqueue/river/pull/691).
 
+### Fixed
+
+- 006 migration now tolerates previous existence of a `unique_states` column in case it was added separately so that the new index could be raised with `CONCURRENTLY`. [PR #691](https://github.com/riverqueue/river/pull/691).
+
 ## [0.14.2] - 2024-11-16
 
 ### Fixed

riverdriver/riverdatabasesql/migration/main/006_bulk_unique.up.sql

@@ -20,7 +20,10 @@ $$;
 --
 -- Add `river_job.unique_states` and bring up an index on it.
 --
-ALTER TABLE river_job ADD COLUMN unique_states BIT(8);
+-- This column may exist already if users manually created the column and index
+-- as instructed in the changelog so the index could be created `CONCURRENTLY`.
+--
+ALTER TABLE river_job ADD COLUMN IF NOT EXISTS unique_states BIT(8);
 
 -- This statement uses `IF NOT EXISTS` to allow users with a `river_job` table
 -- of non-trivial size to build the index `CONCURRENTLY` out of band of this

riverdriver/riverpgxv5/migration/main/006_bulk_unique.up.sql

@@ -20,7 +20,10 @@ $$;
 --
 -- Add `river_job.unique_states` and bring up an index on it.
 --
-ALTER TABLE river_job ADD COLUMN unique_states BIT(8);
+-- This column may exist already if users manually created the column and index
+-- as instructed in the changelog so the index could be created `CONCURRENTLY`.
+--
+ALTER TABLE river_job ADD COLUMN IF NOT EXISTS unique_states BIT(8);
 
 -- This statement uses `IF NOT EXISTS` to allow users with a `river_job` table
 -- of non-trivial size to build the index `CONCURRENTLY` out of band of this