Troubleshoot Post Migration

This topic describes common problems that you might encounter after migrating to Oracle Analytics Cloud and explains how to solve them.

Topics

Report doesn't display as expected. I see the error "BI Server Not Available For Queries"

The error BI Server Not Available For Queries displays for two reasons:
  • The report contains an extremely large query.
  • Oracle Analytics Cloud and Oracle BI Enterprise Edition generate physical queries differently. Oracle BI Enterprise Edition generates inner joins and Oracle Analytics Cloud generates left-outer joins which can cause the performance issue after migration.
To prevent large report queries from getting stuck:
  1. In Semantic Modeler, navigate to the Physical Layer, right-click the source database, click Edit, and then Advanced.
  2. Enable the database feature PERF_PREFER_INTERNAL_STITCH_JOIN.Advanced database tab with PERF_PREFER_INTERNAL_STITCH_JOIN enabled
To prevent the performance issue for a single report or all reports:

  • For a single report, enable the property OBIS_PREVENT_EARLY_NODE_FLATTENING_FOR_OUTER_JOINS=1 at the report-level.

  • For all reports, define a session variable in the semantic model with: OBIS_PREVENT_EARLY_NODE_FLATTENING_FOR_OUTER_JOINS=1

    See Define Session Variables.