Neo4j

DBarnhill · 10-16-2018

I've run into a performance issue after adding an index to a integer field. The query plan changes from a simple scan to a merge of two index seeks but the merge operation is a cartesian join. To recreate the problem: CREATE CONSTRAINT ON (g:Gender)...

DBarnhill · 10-03-2018

I installed Neo4j Community Edition 3.4.7 on a Linux server, then loaded it with several gigabytes of data. There are no queries running, but there is one Java thread stuck at 100% CPU. There is no disk I/O. If I try to stop neo4j using sudo syste...

DBarnhill · 10-21-2018

Thanks, this explanation makes sense. For whatever reason adding the index helps now instead of hurts, so it's working like it should, so consider this issue closed until I can get a better case of where it goes wrong. I swear this was causing an i...

DBarnhill · 10-16-2018

Here is the explain output showing the expected 1 gender node row from the gender node seek, but the profile one shows more rows in the actual output. This may be a red herring, just trying to understand why it's slower.

DBarnhill · 10-16-2018

The plan shows 7 rows hit from both sides of the cartesian join. I'm using gender as an example here, but I have other attributes with similar issues that have thousands of nodes in them. They query only gets worse as the number of matches increase...

DBarnhill · 10-08-2018

I figured out last night that what caused it was a date index on a large set of nodes (>120,000,000). If I removed the date index then restarted the server, the problem went away. After looking through the threads the only one that was not waiting...

Neo4j

User Statistics

User Activity

Cartesian join in query plan after adding an index

Neo4j Community Server Thread stuck at 100% for over a day

Re: Cartesian join in query plan after adding an index

Re: Cartesian join in query plan after adding an index

Re: Cartesian join in query plan after adding an index

Re: Neo4j Community Server Thread stuck at 100% for over a day