How long does a PostgreSQL migration take?
The schedule depends on database size, change rate, source engine, object compatibility, network capacity, test coverage, change controls, and the acceptable cutover window. Discovery produces a phased schedule with rehearsal, acceptance, cutover, and rollback gates rather than a fixed duration before the source is assessed.
Can PostgreSQL migration downtime be minimized?
Often, but the achievable cutover window is workload-specific. Backup and restore, pg_upgrade, native logical replication, or a migration service each has different constraints. A minimal-downtime plan measures synchronization lag, controls writes during cutover, validates the target, and defines when to proceed or roll back.
Does PostgreSQL logical replication copy schema changes?
No. Native PostgreSQL logical replication does not replicate schema definitions or DDL. Compatible schema changes must be applied to the subscriber in a controlled sequence, and incompatible changes can stop replication until resolved. Large objects, sequence state, and some object types also need separate handling and validation.
How is source-to-target data integrity validated?
Validation can include scoped row counts, deterministic aggregates or logical digests, constraints, sequences, large objects, critical-query results, permissions, and application tests. PostgreSQL pg_checksums checks physical data-page checksums in a cluster; it is not a source-to-target logical comparison tool.
Can you migrate Oracle, MySQL, or SQL Server to PostgreSQL?
Yes. Cross-engine work includes object inventory, data-type mapping, schema conversion, stored-code and SQL remediation, data movement, application compatibility testing, and operational handover. Automation can accelerate conversion, but engine-specific behavior and business logic still require review and acceptance testing.
Does pg_dump include PostgreSQL large objects?
A full pg_dump includes large objects by default. Selective dumps and schema-only operations can change what is included, and the --large-objects option can be relevant when using selective filters. The restore rehearsal should explicitly verify large objects, ownership, privileges, extensions, and sequence state.
What does a PostgreSQL migration rollback plan contain?
The rollback plan defines a decision deadline, write handling, connection reversal, source readiness, data divergence risk, named owners, and verification steps. Whether rollback is safe depends on what writes reached the target after cutover, so the plan is tested during rehearsal rather than improvised during production change.