You can use EDB runMTK tool for data migration from Oracle, MySQL, and MS SQL servers.

Asynchronous replication is real-time replication. The significant difference between Asynchronous and Synchronous replication is, Synchronous replication would wait for confirmation from the standby server that it has received all the WAL changes, and then only commit confirmation is given for the corresponding transaction, whereas in async replication master database does not wait for confirmation from

BARMAN is a backup tool, so it does not need the Postgres database to install it. Barman documentation gives information about which minimum version of Postgres it supports, and accordingly, you need to install BARMAN software. However, it's always advisable to use the latest version of BARMAN.

There's no specific or standard computation on Postgres database performance running On-Prem and Cloud. It depends on the workload. Most of the cloud vendor provides pre-configured setup in terms of number of CPU, RAM, Storage, Network Bandwidth, etc. Usually, doing a performance or load testing will give the optimal configuration to meet the performance requirement.

There is no limitation of the database size. However, there are customer cases where Postgres is being used for storing Petabyte's size of data. Like any other proprietary database in the market, PostgreSQL can handle TBs of data. The hardware layer is one of the critical components in database sizing.

It's in Asynchronous mode only.

pgBackRest repositories can be in S3, Azure, and GCS compatible object stores to allow the virtually unlimited capacity and retention. Unfortunately, BART & BARMAN cannot directly support store backup on Azure Blob storage.

pgBackRest can encrypt the repository to secure backups wherever stored, while other backup tools like BARMAN & BART don't have any encryption features.

Bi-Directional Replication (BDR) is an asynchronous multi-master replication system for PostgreSQL, specifically designed to allow geographically distributed clusters. Multi-Master Replication in BDR allows efficient replication for both DDL and DML with automatic conflict resolution. It also offers Conflict-free Replicated Data Types (CRDTs), which support merging values from concurrently modified rows.

Yes, you can use all these tools with open-source PostgreSQL. BART is EnterpriseDB subscription-based tool.