I'm a bit stumped.

In my database, I have a relationship like this:

```
(u:User)-[r1:LISTENS_TO]->(a:Artist)<-[r2:LISTENS_TO]-(u2:User)

```

I want to perform a query where for a given user, I find the common artists between that user and every other user.

To give an idea of size of my database, I have about 600 users, 47,546 artists, and 184,211 relationships between users and artists.

The first query I was trying was the following:

```
START me=node(553314), other=node:userLocations("withinDistance:[38.89037,-77.03196,80.467]")

OPTIONAL MATCH 
    pMutualArtists=(me:User)-[ar1:LISTENS_TO]->(a:Artist)<-[ar2:LISTENS_TO]-(other:User)
WHERE
    other:User

WITH other, COUNT(DISTINCT pMutualArtists) AS mutualArtists

ORDER BY mutualArtists DESC
LIMIT 10
RETURN other.username, mutualArtists

```

This was taking around 20 seconds to return. The profile for this query is as follows:

```
+----------------------+-------+--------+------------------------+------------------------------------------------------------------------------------------------+
|             Operator |  Rows | DbHits |            Identifiers |                                                                                          Other |
+----------------------+-------+--------+------------------------+------------------------------------------------------------------------------------------------+
|      ColumnFilter(0) |    10 |      0 |                        |                                                     keep columns other.username, mutualArtists |
|              Extract |    10 |     20 |                        |                                                                                 other.username |
|      ColumnFilter(1) |    10 |      0 |                        |                                                              keep columns other, mutualArtists |
|                  Top |    10 |      0 |                        | {  AUTOINT0}; Cached(  INTERNAL_AGGREGATEb6facb18-1c5d-45a6-83bf-a75c25ba6baf of type Integer) |
|     EagerAggregation |   563 |      0 |                        |                                                                                          other |
|        OptionalMatch | 52806 |      0 |                        |                                                                                                |
|             Eager(0) |   563 |      0 |                        |                                                                                                |
|  NodeByIndexQuery(1) |   563 |    564 |           other, other |                             Literal(withinDistance:[38.89037,-77.03196,80.467]); userLocations |
|          NodeById(1) |     1 |      1 |                 me, me |                                                                          Literal(List(553314)) |
|             Eager(1) |    82 |      0 |                        |                                                                                                |
|          ExtractPath |    82 |      0 |         pMutualArtists |                                                                                                |
|            Filter(0) |    82 |     82 |                        |                                                    (hasLabel(a:Artist(1)) AND NOT(ar1 == ar2)) |
| SimplePatternMatcher |    82 |     82 | a, me, ar2, ar1, other |                                                                                                |
|            Filter(1) |     1 |      3 |                        |               ((hasLabel(me:User(3)) AND hasLabel(other:User(3))) AND hasLabel(other:User(3))) |
|  NodeByIndexQuery(1) |   563 |    564 |           other, other |                             Literal(withinDistance:[38.89037,-77.03196,80.467]); userLocations |
|          NodeById(1) |     1 |      1 |                 me, me |                                                                          Literal(List(553314)) |
+----------------------+-------+--------+------------------------+------------------------------------------------------------------------------------------------+

```

I was frustrated. It didn't seem like this should take 20 seconds.

I came back to the problem later on, and tried debugging it from the start.

I started to break down the query, and I noticed I was getting much faster results. Without the Neo4J Spatial query, I was getting results in about 1.5 seconds.

I finally added things back, and ended up with the following query:

```
START u=node(553314), u2=node:userLocations("withinDistance:[38.89037,-77.03196,80.467]")

OPTIONAL MATCH 
    pMutualArtists=(u:User)-[ar1:LISTENS_TO]->(a:Artist)<-[ar2:LISTENS_TO]-(u2:User)
WHERE
    u2:User

WITH u2, COUNT(DISTINCT pMutualArtists) AS mutualArtists

ORDER BY mutualArtists DESC
LIMIT 10
RETURN u2.username, mutualArtists

```

This query returns in 4240 ms. A 5X improvement! The profile for this query is as follows:

```
+----------------------+-------+--------+--------------------+------------------------------------------------------------------------------------------------+
|             Operator |  Rows | DbHits |        Identifiers |                                                                                          Other |
+----------------------+-------+--------+--------------------+------------------------------------------------------------------------------------------------+
|      ColumnFilter(0) |    10 |      0 |                    |                                                        keep columns u2.username, mutualArtists |
|              Extract |    10 |     20 |                    |                                                                                    u2.username |
|      ColumnFilter(1) |    10 |      0 |                    |                                                                 keep columns u2, mutualArtists |
|                  Top |    10 |      0 |                    | {  AUTOINT0}; Cached(  INTERNAL_AGGREGATEbdf86ac1-8677-4d45-967f-c2dd594aba49 of type Integer) |
|     EagerAggregation |   563 |      0 |                    |                                                                                             u2 |
|        OptionalMatch | 52806 |      0 |                    |                                                                                                |
|             Eager(0) |   563 |      0 |                    |                                                                                                |
|  NodeByIndexQuery(1) |   563 |    564 |             u2, u2 |                             Literal(withinDistance:[38.89037,-77.03196,80.467]); userLocations |
|          NodeById(1) |     1 |      1 |               u, u |                                                                          Literal(List(553314)) |
|             Eager(1) |    82 |      0 |                    |                                                                                                |
|          ExtractPath |    82 |      0 |     pMutualArtists |                                                                                                |
|            Filter(0) |    82 |     82 |                    |                                                    (hasLabel(a:Artist(1)) AND NOT(ar1 == ar2)) |
| SimplePatternMatcher |    82 |     82 | a, u2, u, ar2, ar1 |                                                                                                |
|            Filter(1) |     1 |      3 |                    |                      ((hasLabel(u:User(3)) AND hasLabel(u2:User(3))) AND hasLabel(u2:User(3))) |
|  NodeByIndexQuery(1) |   563 |    564 |             u2, u2 |                             Literal(withinDistance:[38.89037,-77.03196,80.467]); userLocations |
|          NodeById(1) |     1 |      1 |               u, u |                                                                          Literal(List(553314)) |
+----------------------+-------+--------+--------------------+------------------------------------------------------------------------------------------------+

```

And, to prove that I ran them both in a row and got very different results:

```
neo4j-sh (?)$ START u=node(553314), u2=node:userLocations("withinDistance:[38.89037,-77.03196,80.467]")
>
> OPTIONAL MATCH
>     pMutualArtists=(u:User)-[ar1:LISTENS_TO]->(a:Artist)<-[ar2:LISTENS_TO]-(u2:User)
> WHERE
>     u2:User
>
> WITH u2, COUNT(DISTINCT pMutualArtists) AS mutualArtists
> ORDER BY mutualArtists DESC
> LIMIT 10
> RETURN u2.username, mutualArtists
> ;
+------------------------------+
| u2.username  | mutualArtists |
+------------------------------+
| "573904765"  | 644           |
| "28600291"   | 601           |
| "1092510304" | 558           |
| "1367963461" | 521           |
| "1508790199" | 455           |
| "1335360028" | 447           |
| "18200866"   | 444           |
| "1229430376" | 435           |
| "748318333"  | 434           |
| "5612902"    | 431           |
+------------------------------+
10 rows
4240 ms
neo4j-sh (?)$ START me=node(553314), other=node:userLocations("withinDistance:[38.89037,-77.03196,80.467]")
>
> OPTIONAL MATCH
>     pMutualArtists=(me:User)-[ar1:LISTENS_TO]->(a:Artist)<-[ar2:LISTENS_TO]-(other:User)
> WHERE
>     other:User
>
> WITH other, COUNT(DISTINCT pMutualArtists) AS mutualArtists
> ORDER BY mutualArtists DESC
> LIMIT 10
> RETURN other.username, mutualArtists;
+--------------------------------+
| other.username | mutualArtists |
+--------------------------------+
| "573904765"    | 644           |
| "28600291"     | 601           |
| "1092510304"   | 558           |
| "1367963461"   | 521           |
| "1508790199"   | 455           |
| "1335360028"   | 447           |
| "18200866"     | 444           |
| "1229430376"   | 435           |
| "748318333"    | 434           |
| "5612902"      | 431           |
+--------------------------------+
10 rows
20418 ms

```

Unless I have gone crazy, the only difference between these two queries is the names of the nodes (I've changed "me" to "u" and "other" to "u2").

Why does that cause a 5X improvement??!?!

If anyone has any insight into this, I would be eternally grateful.

Thanks,

-Adam

---

**EDIT 8.1.14**

Based on @ulkas's suggestion, I tried simplifying the query.

The results were:

```
START u=node(553314), u2=node:userLocations("withinDistance:[38.89037,-77.03196,80.467]")
OPTIONAL MATCH pMutualArtists=(u:User)-[ar1:LISTENS_TO]->(a:Artist)<-[ar2:LISTENS_TO]-(u2:User)
RETURN u2.username, COUNT(DISTINCT pMutualArtists) as mutualArtists
ORDER BY mutualArtists DESC
LIMIT 10

```

~4 seconds

```
START me=node(553314), other=node:userLocations("withinDistance:[38.89037,-77.03196,80.467]")
OPTIONAL MATCH pMutualArtists=(me:User)-[ar1:LISTENS_TO]->(a:Artist)<-[ar2:LISTENS_TO]-(other:User)
RETURN other.username, COUNT(DISTINCT pMutualArtists) as mutualArtists
ORDER BY mutualArtists DESC
LIMIT 10

```

~20 seconds

So bizarre. It seems as though literally the named nodes of "other" and "me" cause the query time to jump tremendously. I'm very confused.

Thanks,
-Adam