Symptoms

Upgrading confluence in Oracle hangs and the following appears in the atlassian-confluence.log:

DefaultSiteMigrator:thread-1 - Migration progress 40,831 of 41,341 pages (98%); 117/341 in this batch required migration.

Cause

The database is not able to process the batch default size which is 500 according this page. In the code, Confluence changes the number of executed threads in parallel to be 1 to avoid deadlocks when using Oracle or SQL server.

Workaround

Rollback the upgrade and modify the confluence.wiki.migration.batch.size from 500 to 1 and perform the upgrade again by following the System Properties article which specifies that we need to perform the following tasks:

1. Shutdown Confluence

2. Add the following system property (See: Configuring System Properties):

   -Dconfluence.wiki.migration.batch.size=1 

3. Restart Confluence