Can't create unique constraint in Neo4J

Question

I am attempt to create a constraint like this:

CREATE CONSTRAINT ON (a:forecast) ASSERT a.match IS UNIQUE

but I get this error:

Unable to create Constraint( name='constraint_9615361a', type='UNIQUENESS', schema=(:forecast {match}) ):

I have the Neo4J community edition 4.2.3, but judging by the documentation I should be allowed to create this type of constraint. What gives?

Answer 1

You can check if there is uniqueness on forecast {match} by running this.

MATCH (a:forecast) 
RETURN a.match, count(*) LIMIT 5

If you see a value > 1 in count() then forecast.match is not unique.

Note: count() is sorting in descending order in my desktop. In case it is not, then run below:

MATCH (a:forecast) 
WITH a.match as match, count(*) as cnt
RETURN match, cnt ORDER by cnt DESC LIMIT 5

Answer 2

Late reply, but still.

I was struck by the same error now (with 4.4.3) and it was lack of free space on drive.

Wasted half an hour, digging in absolutely wrong direction. I create database with --skip-duplicate-nodes=true flag, so of course there couldn't be any duplicates.