Adding DuckPGQ extension

extensions/duckpgq/description.yml

@@ -0,0 +1,43 @@
+extension:
+  name: duckpgq
+  description: Extension that adds support for SQL/PGQ and graph algorithms
+  version: 0.0.1
+  language: C++
+  build: cmake
+  license: MIT
+  maintainers:
+    - Dtenwolde
+
+repo:
+  github: cwida/duckpgq-extension
+  ref: 6c06589fb8fe3293bf3b31f5d8e89177504edf5f
+
+docs:
+  hello_world: |
+    CREATE TABLE Person as select * from 'https://gist.githubusercontent.com/Dtenwolde/2b02aebbed3c9638a06fda8ee0088a36/raw/8c4dc551f7344b12eaff2d1438c9da08649d00ec/person-sf0.003.csv';
+    CREATE TABLE Person_knows_person as select * from 'https://gist.githubusercontent.com/Dtenwolde/81c32c9002d4059c2c3073dbca155275/raw/8b440e810a48dcaa08c07086e493ec0e2ec6b3cb/person_knows_person-sf0.003.csv';
+
+    CREATE PROPERTY GRAPH snb
+      VERTEX sABLES (
+        Person
+      )
+    EDGE TABLES (
+      Person_knows_person 	SOURCE KEY (Person1Id) REFERENCES Person (id)
+       DESTINATION KEY (Person2Id) REFERENCES Person (id)
+       LABEL Knows
+    );
+
+    FROM GRAPH_TABLE (snb
+      MATCH (a:Person)-[k:knows]->(b:Person)
+      COLUMNS (a.id, b.id)
+    )
+    LIMIT 1;
+
+    from local_clustering_coefficient(snb, person, knows);
+
+    DROP PROPERTY GRAPH snb; 
+
+  extended_description: |
+    The DuckPGQ extension supports the SQL/PGQ syntax part of the official SQL:2023 standard developed by ISO. 
+    Specifically, it introduces visual graph pattern matching and more concise syntax for path-finding.
+    The extension is an ongoing research project and a work in progress.