Ora2Pg vs Spanner migration tool

Ora2Pg is free, self-hosted software for assessing and migrating databases to PostgreSQL. It scans Oracle databases, extracts structures or data, and generates SQL; the site also lists MySQL as a source and mentions MariaDB and Microsoft SQL Server migration. Reports can estimate migration difficulty and cost. Exports include tables, views, indexes, constraints, functions, triggers, procedures, and packages, with basic automatic PL/SQL-to-PL/pgSQL conversion. Data can be exported completely or selected with a WHERE clause, including Oracle BLOBs as PostgreSQL BYTEA. Ora2Pg can generate Pentaho Data Integrator XML, send spatial geometries to PostGIS, and export DBLINK as Oracle FDW. By default it writes files for psql loading, while direct PostgreSQL import is available after configuring a connection. Oracle migrations require Perl 5.10 or later, DBI, and Oracle client libraries; other sources need their drivers and client dependencies. Generated Oracle-specific PL/SQL may require manual review and changes. The software is distributed under GPL version 3 or later.

Spanner migration tool has no write-up on Specifiction yet; its figures are above.