UPDATE

SPARQL UPDATE modifies the graph by inserting and deleting triples. In Poliglot, UPDATE is primarily used in reconciliation scripts that retract stale statements when new data arrives.

The examples on this page assume the following prefixes:

PREFIX tasks: <https://example.org/spec/tasks#>

INSERT DATA

Add triples directly:

PREFIX tasks: <https://example.org/spec/tasks#>

INSERT DATA {
    tasks:123 tasks:title "Review Q3" .
    tasks:123 tasks:status tasks:Open .
}

DELETE DATA

Remove specific triples:

PREFIX tasks: <https://example.org/spec/tasks#>

DELETE DATA {
    tasks:123 tasks:status tasks:Open .
}

The triples must match exactly. If they don't exist, nothing happens.

DELETE/INSERT WHERE

Conditionally delete and insert in one operation:

PREFIX tasks: <https://example.org/spec/tasks#>

DELETE {
    ?task tasks:status ?oldStatus .
}
INSERT {
    ?task tasks:status tasks:InProgress .
}
WHERE {
    ?task a tasks:Task ;
          tasks:title "Review Q3" ;
          tasks:status ?oldStatus .
}

The WHERE clause finds matching data. DELETE removes the matched triples. INSERT adds new triples. Both use variables bound by the WHERE clause.

DELETE WHERE (Shorthand)

When the DELETE pattern matches the WHERE pattern exactly:

PREFIX tasks: <https://example.org/spec/tasks#>

DELETE WHERE {
    ?task a tasks:Task ;
          tasks:status tasks:Completed .
}

Removes all triples matching the pattern.

Graph-Scoped Updates

Target a specific named graph:

PREFIX tasks: <https://example.org/spec/tasks#>

INSERT {
    GRAPH ?g {
        ?summary tasks:totalOpen ?count .
    }
}
WHERE {
    SELECT (COUNT(?task) AS ?count) WHERE {
        ?task a tasks:Task ;
              tasks:status tasks:Open .
    }
}

Reconciliation Pattern

The most common UPDATE pattern in Poliglot is the reconciliation script. It retracts statements from the default graph that aren't present in a new dataset (?changeset):

PREFIX tasks: <https://example.org/spec/tasks#>

DELETE { ?s ?p ?o }
WHERE {
    ?s a tasks:Task ;
       ?p ?o .
    FILTER(?p IN (tasks:title, tasks:status, tasks:assignee))
    FILTER NOT EXISTS {
        GRAPH ?changeset { ?s ?p ?o }
    }
}

See Reconciliation for the full mechanics.