Add live migration from postgres (#2759)

* Add live migration from postgres

* Apply suggestions from code review

Co-authored-by: James Guthrie <[email protected]>
Signed-off-by: alejandrodnm <[email protected]>

* Add prepare source section

* Minor tweaks and clarification

* Populate live migration index page

---------

Signed-off-by: alejandrodnm <[email protected]>
Co-authored-by: James Guthrie <[email protected]>
Co-authored-by: James Guthrie <[email protected]>

Author: alejandrodnm

migrate/dual-write-and-backfill/dual-write-from-postgres.md

@@ -18,6 +18,7 @@ import SourceTargetNote from "versionContent/_partials/_migrate_source_target_no
 import DumpDatabaseRoles from "versionContent/_partials/_migrate_dual_write_dump_database_roles.mdx";
 import Step6eTurnOnCompressionPolicies from "versionContent/_partials/_migrate_dual_write_6e_turn_on_compression_policies.mdx";
 import Step6aThroughc from "versionContent/_partials/_migrate_dual_write_6a_through_c.mdx";
+import ExplainPgDumpFlags from "versionContent/_partials/_migrate_explain_pg_dump_flags.mdx";
 
 # Dual-write and backfill from PostgreSQL database
 

migrate/index.md

@@ -35,8 +35,9 @@ migrating from PostgreSQL.
 
 If you're using PostgreSQL, you may also have heard of logical replication
 being the recommended strategy for migrations with low downtime. Currently,
-TimescaleDB doesn't work with logical replication, so this is not a viable
-option, but we are actively working on making this possible.
+TimescaleDB supports logical replication only from sources that are using
+PostgreSQL without Timescale. There's active work being made for supporting
+Timescale sources.
 
 If you're migrating from something other than PostgreSQL, and don't want to use
 the dual-write and backfill approach, then the easiest way to move your data to

migrate/live-migration/index.md

@@ -0,0 +1,45 @@
+---
+title: Live migration
+excerpt: Migrate an entire database with low downtime
+products: [cloud]
+keywords: [migration, low-downtime, backup]
+tags: [recovery, logical backup, replication]
+---
+
+# Live migration
+
+Live migration is a migration strategy to move a large amount of data
+(100 GB-10 TB+) with low downtime (on the order of minutes of
+downtime). It is significantly more complicated to execute than a migration
+with downtime using [pg_dump/restore][pg-dump-and-restore], but supports more
+use-cases and has less requirements than the [dual-write and backfill] method.
+
+<SourceTargetNote />
+
+Live migration leverages Postgres' built-in replication functionality to
+provide a seamless migration with very little application downtime.
+
+Roughly, it consists of four steps:
+
+1. Prepare and create replication slot in source database.
+2. Copy schema from source to target, optionally enabling hypertables.
+3. Copy data from source to target while capturing changes.
+4. Apply captured changes from source to target.
+
+Currently live migration only supports migrating from PostgreSQL, but we are
+actively working on supporting TimescaleDB.
+
+Live migration works well when:
+- Large, busy tables have primary keys, or don't have many `UPDATE` or
+  `DELETE` statements.
+- The insert workload does not exceed 20'000 rows per second, and
+  inserts are batched. If your application exceeds this, you should use
+  the [dual-write and backfill] migration method.
+
+For more information, consult the step-by-step migration guide:
+
+- [Live migration from PostgreSQL][from-postgres]
+
+[from-postgres]: /migrate/:currentVersion:/live-migration/live-migration-from-postgres/
+[pg-dump-and-restore]: /migrate/:currentVersion:/pg-dump-and-restore/
+[dual-write and backfill]: /migrate/:currentVersion:/dual-write-and-backfill/