• Project: https://github.com/HaloLab001/halo_migrate

halo_migrate is a Halo/PostgreSQL extension and CLI which lets you make schema changes to tables and indexes. Unlike ALTER TABLE it works online, without holding a long lived exclusive lock on the processed tables during the migration. It builds a copy of the target table and swaps them.

Please check the documentation (in the doc directory or online) for installation and usage instructions.

Forked from the excellent pg_migrate project (https://github.com/phillbaker/pg_migrate).

Halo >= 14, PostgreSQL >= 14

Get the source from project's git site:

git clone https://github.com/HaloLab001/halo_migrate.git

Then to make && make install, for example, for Halo 14:

export USE_PGXS=1
make
make install

Load the halo_migrate extension in the database you want to work on:

psql -c "DROP EXTENSION IF EXISTS halo_migrate cascade; CREATE EXTENSION halo_migrate" -d halo0root

halo_migrate --table=my_table --alter='ALTER COLUMN id TYPE bigint' # Add --execute to run

halo_migrate --table=my_table --alter='ADD COLUMN foo integer NOT NULL DEFAULT 42' # Add --execute to run

• Unique constraints are converted into unique indexes, they are equivalent in Halo/PostgreSQL. However, this may be an unexpected change.
• Index names on the target table and foreign key constraints are changed during the migration.
  • If the generated names are > 63 characters, this will likely break
• If the target table is used in views, those objects will continue to reference the original table - this is not supported currently.
  • If the target table is used in stored procedures, those functions are stored as text so are not linked through object IDs and will reference the migrated table.
• DDL to drop columns or add columns without a default is not currently supported
• Hosted PG databases (RDS, Cloud SQL) are not supported because they do not allow installing custom extensions.