[OAK-6735] Lucene Index: improved cost estimation by using document count per field

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7.4
• Fix Version/s: 1.7.11, 1.8.0
• Component/s: lucene, query
• Labels: doc-impacting
• Epic Link: indexer resilience
• Assignee: Vikas Saurabh
• Reporter: Thomas Mueller
• Created: 27/Sep/17 13:40
• Updated: 08/Oct/19 15:21
• Resolved: 02/Nov/17 21:25

Description

The cost estimation of the Lucene index is somewhat inaccurate because (by default) it just used the number of documents in the index (as of Oak 1.7.4 by default, due to OAK-6333).

Instead, it should use the number of documents for the given fields (the minimum, if there are multiple fields with restrictions).

Plus divided by the number of restrictions (as we do now already).

Issue Links

• breaks: OAK-6902 Cost estimation for path tranformable queries is incorrect
• is related to: OAK-5449 Cost calculation for one matching property restriction/sorting results in selection of wrong index
• is related to: OAK-7300 Lucene Index: per-column selectivity to improve cost estimation
• is related to: OAK-6333 IndexPlanner should use actual entryCount instead of limiting it to 1000
• relates to: OAK-6734 IndexPlan: add supportsPathRestrictions