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Aggregation

This page covers an aggregation of TypeQL Get query results.

Syntax

TypeQL supports the following types of aggregation:

  • count — Get the total number of results returned.

  • sum-- Get the sum of the long or double values of the specified variable.

  • max — Get the maximum value among the long or double values of the specified variable.

  • min — Get the minimum value among the long or double values of the specified variable.

  • mean — Get the average value of the long or double values of the specified variable.

  • median — Get the median value among the long or double values of the matched variable.

  • std — Get the sample standard deviation value among the long or double values of the matched variable.

They are used at the end of a query.

Behavior

A Get query without aggregation or grouping returns a stream of ConceptMaps to represent every matched solution for its pattern. With aggregation, the query performs calculation on the collection of ConceptMaps and returns a single value. Aggregation can be used alongside grouping and in subqueries, which affects the output.

Usage for counting results

For this example, use a database with the IAM schema and sample data loaded.

For any Get query, to count the number of results returned, add the count keyword at the end of the query with a semicolon.

Count example
match
$o isa object, has path $fp;
get;
count;

Notice, that count keyword uses no variables, as it counts only the number of results, regardless of contents. Changing the variables in the get clause of a query can lead to changing the number of results, due to deduplication (the same result can’t be returned twice). See the next example below.

Usage for numeric values

For this example, use a database with the IAM schema and sample data loaded.

For long or double values represented by a value variable or by a concept variable mapped to an attribute, we can use aggregation to compute an output based on all returned values.

Aggregation example
match
$f isa file, has size-kb $s;
get $f, $s;
sum $s;

Omitting the variable $f in the get clause of the above query will result in missing all duplicated values of $s from the aggregation. For more information, see the number of results section on the Get query page.

Learn more

Learn about results grouping in TypeQL.

Learn about Get queries in TypeQL.

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