doc/postgres.md: document being clearer about data migrations
Change-Id: Ic2b1e7201887ca36d58944020c78f17928262425
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/272794
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
diff --git a/doc/postgres.md b/doc/postgres.md
index b52bae6..a883dc8 100644
--- a/doc/postgres.md
+++ b/doc/postgres.md
@@ -118,6 +118,9 @@
[golang-migrate/migrate/MIGRATIONS.md](https://github.com/golang-migrate/migrate/blob/master/MIGRATIONS.md)
for details.
+If your migration requires that data be transformed, or that all modules must be
+reprocessed, explain in the `up.sql` file how to carry out the data migration.
+
### Applying migrations for local development
Use the `migrate` CLI:
