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Applying a patch without downtime

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Updated on April 12, 2022

The Pega patch process is zero-downtime for highly available systems when you use the out-of-place process so you can continue working in your application while you patch your system.

To review the requirements and tasks associate with creating a highly available system, see Configuring high availability deployments.

The patch process involves four schemas:

  • Data schema – your existing data schema. This will be your data schema after the patch as well.
  • Rules schema – your existing rules schema. This schema is updated during the patch.
  • A temporary data schema (Dtmp) – a schema you create on the same database for temporarily staging the data during the patch. You discard this schema after the patch.
  • New rules schema (Rn) – a rules schema you create on the same database for staging the rules during the patch. This schema will become the rules schema after the patch.

Pega provides client-run scripts that copy and replace application rules and that copy data between these schemas appropriately throughout the patch as described below.

Apply patches by completing the following steps:

  1. Prepare the cluster for the patch by configuring the high availability cluster settings.
  2. Create a new rules schema and a new temporary data schema in your existing database. Leave these new schemas empty.

  3. Migrate the rules structure and content and data structure from the existing rules and data schemas to the new rules and temporary data schemas. Running the migration script creates any required tables in the new rules and temporary data schemas, and copies and moves the rule content.

  4. Patch the new rules schema. This process uses the temporary data schema in which it creates and modifies any necessary data tables to store interim data content; these tables and data are discarded when the temporary data schema is removed.

  5. For Oracle databases, you must grant access to the new rules schema tables by using again to generate the necessary rules objects (GRANT statements) which will link the existing data schema to the new rules schema after you patch the new rules schema.
  6. Patch the existing data schema.

  7. Redeploy the application to run using the new rules, as described in Reconfiguring the application server.

  8. Revert the high availability cluster settings you modified at the beginning of the patch process.
  9. Delete the temporary data schema from your database.
  • Previous topic Patching systems without downtime (for Pega Platform version 8.4 and later)
  • Next topic For High Availability systems: Preparing the cluster for patching
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