AllegroGraph aggregate query
AllegroGraph is a Graph database that supports multiple aggregate queries. This database stores data in triples, each consisting of a subject, predicate, and object.
The following are some common aggregation query types and examples of using AllegroGraph to implement them. We will use the following fictional table structure and sample data:
Table structure:
-Entity Table: Contains the entity ID and name.
-Relationship table: Contains relationship ID, subject ID, and object ID.
Sample data:
Entity table:
ID | Name
---|----
1 | Alice
2 | Bob
3 | Charlie
Relationship table:
ID | Subject ID | Object ID
---|------------|----------
1 | 1 | 2
2 | 1 | 3
3 | 2 | 3
1. Count: Counts the number of tuples that meet specific conditions.
Example: Calculate the quantity of all entities.
sparql
SELECT (COUNT(?entity) AS ?count)
WHERE {
?entity a :Entity .
}
Result:
+-------+
|Count|
+-------+
|3|
+-------+
2. Sum (SUM): Calculate the sum of specific attributes.
Example: Calculate the quantity of all relationships.
sparql
SELECT (COUNT(?relation) AS ?count)
WHERE {
?relation a :Relation .
}
Result:
+-------+
|Count|
+-------+
|3|
+-------+
3. Average Value (AVG): Calculate the average value of a specific attribute.
Example: Calculate the average value of relationship ID.
sparql
SELECT (AVG(?id) AS ?avg)
WHERE {
?relation a :Relation .
?relation :ID ?id .
}
Result:
+-----+
|Avg|
+-----+
|2|
+-----+
4. Maximum value (MAX): Find the maximum value for a specific attribute.
Example: Find the maximum value of entity ID.
sparql
SELECT (MAX(?id) AS ?max)
WHERE {
?entity a :Entity .
?entity :ID ?id .
}
Result:
+-----+
|Max|
+-----+
|3|
+-----+
5. Minimum value (MIN): Find the minimum value for a specific attribute.
Example: Find the minimum value for entity ID.
sparql
SELECT (MIN(?id) AS ?min)
WHERE {
?entity a :Entity .
?entity :ID ?id .
}
Result:
+-----+
|Min|
+-----+
|1|
+-----+
6. GROUP BY: Grouping data based on specific attributes.
Example: Group the relationship table by entity ID and calculate the number of relationships corresponding to each entity ID.
sparql
SELECT ?subjectID (COUNT(?relation) AS ?count)
WHERE {
?relation a :Relation .
?relation :Subject ID ?subjectID .
}
GROUP BY ?subjectID
Result:
+-----------+-------+
|SubjectID | count|
+-----------+-------+
|1 | 2|
|2 | 1|
+-----------+-------+
These are examples of common aggregation query types supported by AllegroGraph. According to specific business requirements, other query functions and aggregation functions can also be combined to achieve more complex queries. Please adjust the namespace, predicate, and variable names in the query statement according to the actual situation.
