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I am using Neo4J to represent texts; in the simplest case a text is a sequence of words joined by the relationship LEMMA_TEXT.

I am trying to find the Nth word after a known word, with a query that looks something like this.

MATCH (anchor)-[:LEMMA_TEXT*32]->(word) 
WHERE id(anchor) = 3275 
RETURN word

In one particular case, if I increase the path length to 33, I get this error:

Neo.DatabaseError.Statement.ExecutionFailure: There is no spoon.

And yet the following query returns the correct result.

MATCH (anchor)-[:LEMMA_TEXT*32]->(word)-[:LEMMA_TEXT]->(next) 
WHERE id(anchor) = 3275 
RETURN next

which demonstrates that the node I want exists and is reachable.

Where is the section of the manual that tells me how to bend the spoon with my mind? More importantly, what does this actually mean?!

Tim Kuehn
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tla
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2 Answers2

2

If anything breaks at number like 33, it means that there was a restriction upto 32, why 32? 2^5.

It's not trivial that most of the restrictions are in a factor of 2, MongoDB document size cannot be more than 16 MB, on a collection there could be maximum index, no more than 64. etc.

why it works as 32 and then next, because till 32 it can achieve in one operation and for last one it can see the next one as another operation. But it cannot go for 33 in one operation.

Most of these restrictions are basically sanity check though and not really technical boundary.

As for why it is almost always a factor of 2, I want someone else to answer or in other words I don't know.

Rahul Kumar
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0

Have you tried splitting the landing and the search statements in 2?

Plus you should add the label for the text word (forormance)

Example:

MATCH (anchor)
WHERE id(anchor) = 3275 
WITH anchor
MATCH (anchor)-[:LEMMA_TEXT*32]->(word) 
RETURN word

You get the same error?

mmvsbg
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nrgjack
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