I have used Neo4J ETL tool and create a Neo4J database from Postgres SQL and this looks perfect. I can see all nodes, relationships, data, etc.
Now I want to see all the database file, the Cypher queries for all node and relationship creation along with different constraint applied to this database.
How can I view this? I can see database folder is empty for Neo4J home,
C:\Users\I\.Neo4jDesktop\relate-data\dbmss\dbms-9cf178b6-f37f-4139-8b80-dadf0fa03866\data\databases
2nd question, can I generates graphql schema from the Cypher script using any tool or some mean?
Thanks!
I think below codes can help you to get meta-data and schema
// Show meta-graph
CALL db.schema.visualization()
// List node labels
CALL db.labels()
// List relationship types
CALL db.relationshipTypes()
Related
I'm looking for a Cypher query that will show an excerpt of the data in a Neo4j database. I need this to provide a quick overview of what kind of data can be found in the db.
The query should show a certain number of nodes for all labels with all possible relations between them. Basically I want to get a subset of the nodes in the database which contains the full complexity of the data in the database.
I tried to accomplish this with LIMIT but this only limits the total number of nodes returned.
Thanks for your help
There's a set of procedures for this via the APOC library(Neo4j 3x): apoc.meta.graph
e.g. CALL apoc.meta.graph will iterate over the graph and collect labels and relationships it finds.
There's a writeup of the meta procedures in this blog post.
I've got my graph database, populated with nodes, relationships, properties etc. I'd like to see an overview of how the whole database is connected, each relationship to each node, properties of a node etc.
I don't mean view each individual node, but rather something like an ERD from a relational database, something like this, with the node labels. Is this possible?
You can use the metadata by running the command call db.schema().
In Neo4j v4 call db.schema() is deprecated, you can now use call db.schema.visualization()
As far as I know, there is no straight-forward way to get a nicely pictured diagram of a neo4j database structure.
There is a pre-defined query in the neo4j browser which finds all node types and their relationships. However, it traverses the complete graph and may fail due to memory errors if you have to much data.
Also, there is neoprofiler. It's a tool which claims to so what you ask. I never tried and it didn't get too many updates lately. Still worth a try: https://github.com/moxious/neoprofiler
Even though this is not a graphical representation, this query will give you an idea on what type of nodes are connected to other nodes with what type of relationship.
MATCH (n)
OPTIONAL MATCH (n)-[r]->(x)
WITH DISTINCT {l1: labels(n), r: type(r), l2: labels(x)}
AS `first degree connection`
RETURN `first degree connection`;
You could use this query to then unwind the labels to write that next cypher query dynamically (via a scripting language and using the REST API) and then paste that query back into the neo4j browser to get an example set of the data.
But this should be good enough to get an overview of your graph. Expand from here.
I know that neo4j stores data structured in graphs rather than in tables. In RDBMS we will be having schemas of the tables but in neo4j we will not be having the tables. Only nodes, relations and properties are defined. So is there any concept of metadata in neo4j. Like is there any information stored about nodes, relationships in the database? If yes, how and what it stores in the metadata? Also where can we find the metadata related information in the graph database (location)
Thanks,
Neo4J doesn't directly store metadata in the way that you're looking for. The NeoProfiler tool was written precisely for this purpose. You can run it on a Neo4J database, and it will pull out as much information on labels, indexes, constraints, properties, nodes, and relationships as it can. The way that this works isn't too far off of the queries that #ulkas suggests in the other answer here, the output is just much better.
More broadly, in an RDBMS the schema information you pull out substantially constrains the database. The schema there is like a set of rules; you can't insert data unless it conforms to that schema. In Neo4J, because it's so flexible, even if there was a schema it would just be documentation of what's there, it would not be a set of constraints on what you can put in. At any time, you can insert new data that has nothing to do with the present schema (except that you can't violate things like uniqueness constraints).
If you want to see an equivalent schema for your database in neo4j, check out neoprofiler linked above. A few people out there have written about "metagraphs" - that is, they talk about representing a neo4j schema as a graph itself, where for example a node refers to a label. Relationships from that "label node" then go out to other kinds of label nodes, specifying what sorts of relationships can exist between nodes. For example, nodes labeled "Employee" may frequently have "works_for" relationships to nodes of label "Company".
no, direct metadata are not present. the maximum you can do is to query all the structure types and have a small inside what kind of graph could be stored in the db.
START r=rel(*)
RETURN type(r), count(*)
START n=node(*)
RETURN labels(n), count(*)
the specific database files are stored in the folder data/graph.db but besides some index and key files they are binary and not easy to read.
Meanwhile there is the official APOC Library.
This includes functions like apoc.meta.graph, apoc.meta.schema and others.
The link above describes the installation, if you run into sandbox errors, check the answers in this question
I want to create a new Database in neo4j using Cypher as I am not a Java (or Programming language) guy but a Database person ....Could I create a neo4j database using Cypher before creating nodes and relationships ...I am using ne04j community console and would like to create a new database
Thanks !
There is only one database.
You can clean out your current data by either stopping the server and removing the database on disk /path/to/neo4j/data/graph.db and starting it again.
Or by executing a Cypher statement like:
MATCH (n)
OPTIONAL MATCH (n)-[r]->()
DELETE n,r
You dont need to create a new database as(neo4j folder)\data\graph.db is the default path for the database.Neo4j is different from the relational databases.Folder it self is a database.In a graph database you have to create three things: nodes,relationships and properties.
If you want to change the database path you can change the path in conf/neo4j-server.properties.
You can also refer below link:
How to delete/create databases in Neo4j?
Can u please share any links/sample source code for generating the graph using neo4j from Oracle database tables data .
And my use case is oracle schema table names as Nodes and columns are properties. And also need to genetate graph in tree structure.
Make sure you commit the transaction after creating the nodes with tx.success(), tx.finish().
If you still don't see the nodes, please post your code and/or any exceptions.
Use JDBC to extract your oracle db data. Then use the Java API to build the corresponding nodes :
GraphDatabaseService db;
try(Transaction tx = db.beginTx()){
Node datanode = db.createNode(Labels.TABLENAME);
datanode.setProperty("column name", "column value"); //do this for each column.
tx.success();
}
Also remember to scale your transactions. I tend to use around 1500 creates per transaction and it works fine for me, but you might have to play with it a little bit.
Just do a SELECT * FROM table LIMIT 1000 OFFSET X*1000 with X being the value for how many times you've run the query before. Then keep those 1000 records stored somewhere in a collection or something so you can build your nodes with them. Repeat this until you've handled every record in your database.
Not sure what you mean with "And also need to genetate graph in tree structure.", if you mean you'd like to convert foreign keys into relationships, remember to just index the key and in stead of adding the FK as a property, create a relationship to the original node in stead. You can find it by doing an index lookup. Or you could just create your own little in-memory index with a HashMap. But since you're already storing 1000 sql records in-memory, plus you are building the transaction... you need to be a bit careful with your memory depending on your JVM settings.
You need to code this ETL process yourself. Follow the below
Write your first Neo4j example by following this article.
Understand how to model with graphs.
There are multiple ways of talking to Neo4j using Java. Choose the one that suits your needs.