This topic describes basic concepts behind the creation of a dSource from PostgreSQL instance.
For an overview of all dSource related actions, please visit Managing data sources and syncing data in the Getting Started section of the Datasets documentation.
When linking a dSource from a PostgreSQL source database, Delphix offers different methods of capturing backup information:
dSource created with External Backup and syncing data with WAL files.
dSource created with External Backup and syncing data with PostgreSQL Streaming Replication.
dSource created with Delphix Initiated Backup, leveraging PostgreSQL Streaming Replication to sync data from the source database.
dSource created with Delphix Initiated Backup, leveraging Single database ingestion to sync data from the source database.
dSource created with the Staging Push method.
If you are using an external backup and have checked both options above, then PostgreSQL Streaming Replication will take precedence over syncing with WAL files.
For Delphix initiated and external backups, the streaming replication is monitored by reading the Postgres database logs every minute. If the streaming replication stops due to any reason, a fault is generated and an error message is displayed under the Status tab.
The snapshot operation will also fail if the streaming replication stops with a fault.
After obtaining the initial snapshot and linking the dSource, the Delphix Engine keeps the staging and the source database in sync by monitoring the source database for new transaction logs on the staging target and then applying those transaction logs on the staging database. PostgreSQL streaming replication protocol is used to achieve data replication between the source database and the staging database.
We can also use the source host as a staging host because the PostgreSQL database runs on different ports.