Scalable RETURN all unstructured properties of node

[semihsalihoglu-uw]

Currently, when a user asks the query:

MATCH (a:Person)
WHERE a.firstName = "Ramon"
RETURN a

And we are given a graph that has 1000 different possible unstructured properties across Person nodes (which is an information kept in the catalog), we will try to construct a plan with 1000 property readers, what will try to read each possible property one after another, and put a null or a value in one ValueVector. So for a node that has only 1 unstructured property, we will try to read 1000 possible properties. In addition, we will output 999 nulls.

Instead, we should have a special ValueVector (possibly of dataType Map or currently we can call it UnstructuredPropertyMap) that and a special AlllUnstructuredPropertiesReader that reads all unstructured properties of a node and puts it into a single ValueVector.

[andyfengHKU]

Solved in PR #486