Question about index creation in Sandbox

General Graph Academy
1

Dear Neo4j Community,

I have a question about Neo4j indexes and could not find the answer anywhere else and hope this is the right category for this as I thought it might be a newbie question. I am using Neo4j Sandbox and the Recommendations dataset.

In the sandbox the syntax

CREATE INDEX Index_Name FOR (n:Label) ON (n.property)

does not seem to work whereas the syntax

CREATE INDEX ON :Label(property)

seems to work. In particular, I created a new label and wanted to introduce an index with

CREATE INDEX Test_index FOR (n:NewLabel) ON (n.name)

which gives me the error

Invalid input 'T': expected whitespace, comment, ON, '=', node labels, MapLiteral, a parameter, a parameter (old syntax), a relationship pattern, ',', FROM GRAPH, CONSTRUCT, LOAD CSV, START, MATCH, UNWIND, MERGE, CREATE UNIQUE, CREATE, SET, DELETE, REMOVE, FOREACH, WITH, CALL, RETURN, UNION, ';' or end of input (line 1, column 14 (offset: 13))
"CREATE INDEX Test_index FOR (n:NewLabel) ON (n.name)"

I really don't know what would be wrong with this as it is just like in the Graph Academy described or am I missing something here? However, if I use

CREATE INDEX ON :NewLabel(name)

this works perfectly fine and creates and index. Because of this it won't let me create named indexes.

Thanks a lot for any help on this.

2

what version of Neo4j is in use?

CREATE INDEX ON :Label(property)

was the old syntax and is still supported.

CREATE INDEX Test_index FOR (n:NewLabel) ON (n.name);

was introduced in 4.0.x. So if you are at a Neo4j version less than 4.0.x then this would not work

3

Hello Dana,

Thank you so much, this explains a lot. I am using the Sandbox from the Neo4j Website and you are right, the version is 3.5.17.

I am also struggling with composite indexes. For my new label I create an index

CREATE INDEX ON :NewLabel(name,bornIn)

with name and bornIn existing for all nodes of NewLabel in case this is relevant.

When I look at the query

PROFILE MATCH (n:NewLabel) WHERE EXISTS(n.name) AND EXISTS(n.bornIn) RETURN n

the query planner does not use the index I created, but does a NodeByLabelScan. However, if I create the index just for name or just for born in the query planer uses that respective index and does a NodeIndexScan.

I cannot make any sense of that, is this maybe also due to the older version of the Sandbox? I could not find anything on that.

Thank you so much for your help.

4

The sandbox uses 3.5. This is from the 3.5 Cypher Manual:

Composite indexes are currently not able to support the exists predicate.

Elaine

5

Hello Elaine,

Thank you for the help. That explains a lot.