Skip to content

Filter with pattern expressions documentation #1425

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Oct 7, 2025
Merged

Filter with pattern expressions documentation #1425

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
5cbe1cb
Add pattern expressions
Josipmrden Oct 7, 2025
80e52fa
Apply suggestions from code review
matea16 Oct 7, 2025
39406ef
Merge branch 'memgraph-3-6' into filter-with-pattern-expressions
matea16 Oct 7, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 28 additions & 3 deletions pages/querying/clauses/where.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,8 @@ order to avoid problems with performance or results.
1.4. [Filter with node properties](#14-filter-with-node-properties)<br />
1.5. [Filter with relationship properties](#15-filter-with-relationship-properties)<br />
1.6. [Check if property is not null](#16-check-if-property-is-not-null)<br />
1.7. [Filter with pattern expressions](#17-filter-with-pattern-expressions)<br />
1.7. [Filter with EXISTS expressions](#17-filter-with-exists-expressions)<br />
1.8. [Filter with pattern expressions](#18-filter-with-pattern-expressions)<br />
2. [String matching](#2-string-matching)<br />
3. [Regular Expressions](#3-regular-expressions)
4. [Existential subqueries](#4-existential-subqueries)<br />
Expand Down Expand Up @@ -166,9 +167,9 @@ Output:
+----------------+----------------+
```

### 1.7. Filter with pattern expressions
### 1.7. Filter with EXISTS expressions

Currently, we support pattern expression filters with the `exists(pattern)`
Currently, we support `EXISTS` expression filters with the `exists(pattern)`
function, which can perform filters based on neighboring entities:

```cypher
Expand All @@ -191,6 +192,30 @@ Output:
+----------------+
```

### 1.8. Filter with pattern expressions

Currently, we support pattern expression filters inside the `WHERE` clause.

```cypher
MATCH (p:Person)
WHERE (p)-[:LIVING_IN]->(:Country {name: 'Germany'})
RETURN p.name
ORDER BY p.name;
```

Output:

```nocopy
+----------------+
| c.name |
+----------------+
| Anna |
| John |
+----------------+
```

The pattern expressions can't contain any additional symbols that are not introduced in the previously matched symbols.

## 2. String matching

Apart from comparison and concatenation operators Cypher provides special
Expand Down
1 change: 1 addition & 0 deletions pages/querying/differences-in-cypher-implementations.mdx
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -187,6 +187,7 @@ Such a construct is not supported in Memgraph, but you can use `collect()` [aggr

{<h4 className="custom-header">Patterns in expressions</h4>}
Patterns in expressions are supported in Memgraph in particular functions, like `exists(pattern)`.
Memgraph also supports filtering based on patterns, like `MATCH (n) WHERE NOT (n)-->()`.
In other cases, Memgraph does not yet support patterns in functions, e.g. `size((n)-->())`.
Most of the time, the same functionalities can be expressed differently in Memgraph
using `OPTIONAL` expansions, function calls, etc.
Expand Down