fix: Improve performance for Gravsearch queries #2857
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This is an attempt at a minimally invasive fix for some of the performance issue we face with Gravsearch. Gravsearch queries contain `FILTER NOT EXISTS` blocks which are used to only retrieve resources which were not marked as deleted. For some reason this slows down the query substantially. Replacing this block with a `MINUS` makes simple queries faster. In general, MINUS is often more efficient than FILTER NOT EXISTS for simple cases because it directly computes the difference between two result sets. It can benefit from query optimization and indexing. FILTER NOT EXISTS, especially when used with complex subqueries or patterns, may be slower, as it needs to check for the non-existence of a certain pattern within the result set.
Codecov ReportAll modified lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## main #2857 +/- ##
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+ Coverage 18.00% 88.05% +70.05%
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Files 281 244 -37
Lines 28899 23123 -5776
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+ Hits 5202 20362 +15160
+ Misses 23697 2761 -20936 ☔ View full report in Codecov by Sentry. |
seakayone
requested review from
BalduinLandolt and
mpro7
and removed request for
BalduinLandolt
BalduinLandolt
approved these changes
Sep 29, 2023
Have not measured it exactly: The query in the issue is on a resource of webern restricted to a Bibliography class with two query pattern |
mpro7
approved these changes
Oct 2, 2023
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This is an attempt at a minimally invasive fix for some of the performance issue we face with Gravsearch.
Gravsearch queries contain
FILTER NOT EXISTSblocks which are used to only retrieve resources which were not marked as deleted. For some reason this slows down the query substantially. Replacing this block with aMINUSmakes simple queries faster.For the difference between those two statements in the official SPARQL documentation:
https://www.w3.org/TR/sparql11-query/#neg-notexists-minus
Pull Request Checklist
Task Description/Number
Issue Number: DEV-2714
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