Graph and Cypher in BangDB is quite powerful and allows users to deal with modern and complex use cases. BangDB natively integrates Graph with Stream, which makes in possible to ingest data in stream and keep growing Graph as well. With native AI integration, the data science becomes natural element for Graph. With simple Cypher queries, user can do much more and in real-time for several use cases.

Data in a graph table for BangDB is defined as triples. A triple contains subject, object and relationship (predicate) between them. All data is stored as triple within the DB. BangDB does clever arrangements and housekeeping to store the data such that various queries can be written and run efficiently.

The structure of the query is very similar to “Cypher”. BangDB uses Cypher-like queries to process the data. The basic structures look like following:

QueryDescription
CREATE()-[]->()for creating node or triple
S=>()-[]->()for querying data
<op USING attr1 SORT_DESC attr2 LIMIT n> query1 ++ query2operation on disjoint sets of queries

The "()" denotes subject or object and "[]" denotes relation (predicate) with "->" defining the direction. The arrangement is always "Subject Predicate Object".

The node has a label associated with it. Every node is written as "label:name".

There are basically following keywords associated with all the queries.

Node, entity creation

QueryDescription
CREATEto create a single node, or triple

Running query and selecting data

QueryDescription
S=>namespace for the unit of query
RETURNselecting attributes for any query
WHEREconditions for the query
ASselecting columns/attributes with alias
DATAQUERYfor filtering within node and relations for properties
SORT_DESCfor sorting in descending order
SORT_ASCfor sorting in ascending order
LIMITfor limiting number of selections

Statistics

QueryDescription
COUNTcounting all using COUNT(*) or COUNT(A.col)
UCOUNTunique counting
AVGaverage of any attribute
MINmin value
MAXmax value
STDstandard deviation
SUMsum
EXKURTex-kurtosis
SKEWskewness

Functional properties

QueryDescription
SYMMsymmetric relations
ASYMMasymmetric relations

Graph algos

QueryDescription
ALL_PATHall paths between any two given nodes
SHORT_PATHshortest path between any two given nodes

Set operations

QueryDescriptionVenn diagram
ADDadding two or more sets ( UNION )add (union)
SUBTRACTdifference of two sets ( DIFFERENCE )substract
DIFFERENCEdifference of setsdifference
JOIN or CROSSjoin product of two sets ( INTERSECT )difference
LEFT_JOINleft set and values of joined part of second setleft-join
RIGHT_JOINright set and values of joined part of first setright-join
APPENDappend two sets row wiseappend
PIPEfor piping (or sending) the first list to the second query

Data Science

QueryDescription
SIMILARITYcompute similarities among set of nodes based on various data
CLUSTERto find and natural clusters
CENTRALITYfinding the node centrality
COMMUNITY_DETECTIONfor detecting several communities within graph
GROUPSfinding several groups given properties
ML_ALGOthis brings entire ML algorithms to the Graph, model name is supplied as well
Deep Learning*DNN, RNN, ResNet. Embeddable within graph
Information Extraction*Ontologies or triple generation through IE

Data is processed from left to right. There could be several triples chained to form a query, like.

S1=>()-[]->()-[]->() …

Here in the above example, the first triple will intermediate-output a set of results, these intermediate-output will become input from subsequent processing etc. Therefore, it will keep evaluating from left to right using the intermediate results. The subject for subsequent chained query will be the intermediate result of the previous triple and so on.

In some cases, we would like to keep subject of the first triple as subject for the subsequent triple, then we can use the structure like following. This in contrast with the chain query, where object of the first triple becomes the subject of the second one and so on

S2=>[S1=>()-[]->()]-[]->() …

We will see the examples for these in subsequent sections.

Merger nodes (deep merge)

MERGE function allows us to merge two nodes deeply. Which means all the relationships (in or out) and properties of relationships, properties on node are all merged.

Secondary node is finally deleted and all relationships pointing towards and out of secondary nodes are also moved completely.

Primary node is the node in which the secondary node will get merged. Arrow ('<-') points towards primary node.

To merge node (label:id2) into (label:id1)

MERGE (label:id1)<-[*]-(label:id2)

To merge node (label:id1) into (label:id2)

MERGE (label:id1)-[*]->(label:id2)

'*' could be replaced with ;

KEEP_PRIM_PROP = same as '*', means keep the property of primary node in case of duplicate key

KEEP_SEC_PROP = keep secondary node property in case of clash

KEEP_BOTH = keep duplicate properties (both primary and secondary)

Delete node

DELETE function allows us to delete a node deeply. Which means all the relationships (in or out) and properties of relationships, properties on node are all deleted.

To delete node (label:id)

DELETE (label:id)

We will use BangDB CLI to perform these exercises. But before we go there, let's see how BangDB Cypher is different from the original Cypher.

Checkout a sample use cases here to learn bit more about Graph and Cypher in BangDB.

Checkout the graph document here.