Updating a table using a scalar subselect
But this makes it also easier to write and use them.
Apoc index queries not only return nodes and relationships but also a weight, which is the score returned from the underlying Lucene index. That’s especially helpful for partial and fuzzy text searches.
Returns number of batches and total processed rowsapoc.periodic.iterate('statement returning items', 'statement per item', ) YIELD batches, total - run the second statement for each item returned by the first statement.
Returns number of batches and total processed rowsapoc.periodic.rock_n_roll('some cypher for iteration', 'some cypher as action on each iteration', 10000) YIELD batches, total - run the action statement in batches over the iterator statement’s results in a separate thread.
This can be useful to make easier correlations and equality tests between differently formatted email addresses, and between urls to the same domains but specifying different locations. During a scan the procedure will look at all outgoing relationships of type : X for each node n.
For each of these relationships, it will compute a weight and use that as a vote for the other node’s 'partition' property value.
If you used or wrote procedures in the past, you most probably came across instances where it felt quite unwieldy to call a procedure just to compute something, convert a value or provide a boolean decision.
Functions are more limited than procedures: they can’t execute writes or schema operations and are expected to return a single value, not a stream of values.Indexes are used for finding nodes in the graph that further operations can then continue from.Just like in a book where you look at the index to find a section that interest you, and then start reading from there.A full text index allows you to find occurrences of individual words or phrases across all attributes.Things start to get interesting when we look at how the different entities in Paris are connected to one another.Those procedures are implemented in Java and can be easily deployed into your Neo4j instance, and then be called from Cypher directly.