I must admit I'm quite baffled at this. I've gone through quite a bit of work adding some extra nodes to help make - what would be a really bad range query - profile quite nicely. But it runs incredibly slowly the first time, and subsequently quite fast. I presume this is due to disk access and load…

couple of thoughts. Via the browser if you run :sysinfo it shoudl report 'Page Cache:' details. Page Cache faults would be indicative of getting the data from the file system as opposed to RAM/Page Cache. So if you capture the output of :sysinfo and then run the query for the first time I would …

Thanks for the info! When I run :sysinfo it gives me no page cache metrics: Page Cache Faults - Evictions - File Mappings - Bytes Read - Flushes - Eviction Exceptions - File Unmappings - Bytes Written - I'm guessing this is an Enterprise only feature? Or could this indicate that perhaps the page c…

apologies as I missed that this was a community edition install. :sysinfo will not display the Page Cache detail the auto warm-up of the pagecache over Neo4j restart is also an enterprise only functionality

This reply is mostly going to be a stream-of-consciousness as I try a few things and post the results for anyone else who comes across this post so it can help them as well... So, let's do the math... the profile in the original post took ~7 seconds to run the first time for that chromosome on an A…

Can you supply PROFILE plans with all nodes expanded (double-down arrow in the lower right corner of the result pane). With what you've given us, we can't be fully sure the order the planner has used, and which operations in the plan correspond to which parts of the query.

Sure thing. I'll post 3 queries and the profile plans for each. With the first 2 I would expect the db hits for each of these plans to be identical. The work done me be slightly different, but the result is the same and the properties that need loading are the same as well. So, if there's a reason …

Bump. Curious about any insights from the Neo4j team on this and the questions posed. Thanks!

[image] massung: ompound indexes you may wish to read Compound index no longer being used

Hi there, A db hit is a bit of a bucket term, an interaction with the db (whether it's through the pagecache or hitting disk), as opposed to operations on projected variables already in memory. As such, db hits are not equal to each other in terms of time or effort for execution. They are guides fo…

Andrew, Projecting those values does - in fact - make a considerable improvement. Obviously there's a single db hit per property being projected, but once projected the use of the projected value is much more efficient (it would seem). [plan] At the beginning, projecting the start and end allowed…

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Extremely slow query when profile looks very good?

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duane_nickull (Duane Nickull) October 3, 2019, 5:05am 9

you may wish to read Compound index no longer being used

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Extremely slow query when profile looks very good?

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