Description:

Some complicated custom reports can result in generated queries where the log_visit table is right joined to the segment temporary table, these queries perform poorly because the join plan starts with the right joined log_visit table which has no range conditions, resulting in the entire log_visit table being joined.

The query generator code contains an optimization which will remove any where conditions on joined log tables which duplicate the where condition on the segment temporary table. This makes perfect sense for left joined tables, but not for right joins on the log_visit table.

This PR changes the above query optimization to avoid removing where conditions from the log_visit table if it is right joined to a segment temporary table.

Ref PG-3186

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed