I'm using ne04j 2.1.2 community edition.
I have a nodes with a label called Company and I created these nodes and label by loading CSV file along with the MERGE and CREATE commands.
So in future if my label names changes,say Company to Organization, I wanted to maintain the createddate, UpdatedDate, NewLabelName, OldLabelName values somewhere.
So in order to achieve that I thought of maintaining one master node which holds the label information i.e., it should have the properties like NewLabelName, OldLabelName, CreatedDate, UpdatedDate. So the label name should come from the Master Node to other nodes. Whenever we made any changes to label ,then the corresponding UpdatedDate property value should be updated in the master node and NewLabelName should come from the master node to other nodes (nodes for which that label belongs to) .
Hope you understand the scenario here.
But how can i achieve this ? is it possible to achieve ? if yes, then how can i define the relationship between master and other nodes?
(Here my other nodes are Name of the Companies like Google, Yahoo, Samsung etc.. and those will be having some other child nodes like location)
Please suggest the solution. (I wanted to achieve these using cypher not using java)
Thanks
Although labels can be changed, you should do that rarely (e.g., to recover from a mistake). Changing a large number of labels is very expensive and should never be done as a part of normal processing.
Also, like a Java class name, a label name is not something you'd normally show to end users. So, there is really no reason to ever change them. Just try to pick reasonable label names to start with, and don't plan to change them.
Related
In early editions of Neo4j, Super nodes were typically seen as a bad thing for performance. I have not seen too much about that recently with the 2.X and 3.X releases so was wondering if that was still a problem.
The issue I have is I need to store a finite number of options for a specific Node type. For example, Person and favorite colors. I can store an array in the Person Node that stores the colors the user likes, or I can create a Node for each color and then create a relationship from the Person to the Color Node. It seems the super node option would be faster to query but am worried as super nodes were bad in the past.
If I am trying to look up people who like a specific color, what's the recommended way to store such data in Neo?
I think the major issue here will be that the Color node will become a very connected node.
Maybe you need an Options subgraph to have a template of these options and then :
copy template node option to link this copy with the main entity node
or
copy only the choosen option into a property of the main entity node, like your array proposition
or, if your option has no properties
add label onto your main entity node
I think, even with the increase in performance of hyperlinked nodes with newer Neo4j versions, the read/write time will be always more than the one who has less.
I hope this help a bit.
Say we have a Neo4j database with several 50,000 node subgraphs. Each subgraph has a root. I want to find all nodes in one subgraph.
One way would be to recursively walk the tree. It works but can be thousands of trips to the database.
One way is to add a subgraph identifier to each node:
MATCH(n {subgraph_id:{my_graph_id}}) return n
Another way would be to relate each node in a subgraph to the subgraph's root:
MATCH(n)-[]->(root:ROOT {id: {my_graph_id}}) return n
This feels more "graphy" if that matters. Seems expensive.
Or, I could add a label to each node. If {my_graph_id} was "BOBS_QA_COPY" then
MATCH(n:BOBS_QA_COPY) return n
would scoop up all the nodes in the subgraph.
My question is when is it appropriate to use a garden-variety property, add relationships, or set a label?
Setting a label to identify a particular subgraph makes me feel weird, like I am abusing the tool. I expect labels to say what something is, not which instance of something it is.
For example, if we were graphing car information, I could see having parts labeled "FORD EXPLORER". But I am less sure that it would make sense to have parts labeled "TONYS FORD EXPLORER". Now, I could see (USER id:"Tony") having a relationship to a FORD EXPLORER graph...
I may be having a bout of "SQL brain"...
Let's work this through, step by step.
If there are N non-root nodes, adding an extra N ROOT relationships makes the least sense. It is very expensive in storage, it will pollute the data model with relationships that don't need to be there and that can unnecessarily complicate queries that want to traverse paths, and it is not the fastest way to find all the nodes in a subgraph.
Adding a subgraph ID property to every node is also expensive in storage (but less so), and would require either: (a) scanning every node to find all the nodes with a specific ID (slow), or (b) using an index, say, :Node(subgraph_id) (faster). Approach (b), which is preferable, would also require that all the nodes have the same Node label.
But wait, if approach 2(b) already requires all nodes to be labelled, why don't we just use a different label for each subgroup? By doing that, we don't need the subgraph_id property at all, and we don't need an index either! And finding all the nodes with the same label is fast.
Thus, using a per-subgroup label would be the best option.
I want to change the color of my nodes based on their properties:
Say I have many "Person" nodes. And I want those who live in New York to be red and those who live in Los Angeles to be blue. How would I write that. In cypher or in py2neo?
The styling of nodes and relationships in Neo4j Browser is controlled by a graph style sheet (GRASS), a cousin of CSS. You can view the current style by typing :style in the browser. To edit it, you can click on nodes and relationships and pick colors and sizes, or you can view the style sheet (:style), download it, make changes, and drag-n-drop it back into the view window.
Unfortunately for your case, color can only be controlled a) for all nodes and all relationships or b) for nodes by label and relationships by type. Properties can only be used for the text displayed on the node/rel.
It is not possible to interact with neo4j browser pro-grammatically. But the end goal could be achieved through a hack.
Even though I am a bit late here want to help others who might be finding a way. It is not possible to change the color of the nodes based on the property but there is a way it can be achieved by creating nodes based on the property. Keep in mind that after applying these queries your data wont be the same. So it is always a good idea to keep a backup of your data.
This is how labels are colored by default (Before):
Color based on the property
Suppose there is a label called Case with a property nationality and you want to color the nodes based on nationality. So following query could be used to create labels out of nationality property. For this you will need to install apoc library. check here for installation.
// BY NATIONALITY
MATCH (n:Case)
WITH DISTINCT n.nationality AS nationality, collect(DISTINCT n) AS persons
CALL apoc.create.addLabels(persons, [apoc.text.upperCamelCase(nationality)]) YIELD node
RETURN *
This will return all the people by nationality. Now you can color by country of nationality. Below shows an example.
Color based on the property and load with other labels
Lets say you also have a label called Cluster.The cases are attached to clusters via relationships. Just change the query to following to get the clusters with their relationships to cases.
//BY NATIONALITY WITH CLUSTERS
MATCH (n:Case),(c:Cluster)
WITH DISTINCT n.nationality AS nationality,
collect(DISTINCT n) AS persons,
collect(DISTINCT c) AS clusters
CALL apoc.create.addLabels(persons, [apoc.text.upperCamelCase(nationality)]) YIELD node
RETURN *
It will return cases and clusters with all the relationships. Below shows example.
Please leave an up vote if this was helpful and want to let others know that this is an acceptable answer. Thank you.
You cannot include formatting of the output in Cypher queries in the neo4j browser. Currently, the only way is to change the graph view manually or load a graph style file.
See tutorial here: http://neo4j.com/developer/guide-neo4j-browser/
Also, you cannot interact with the neo4j browser from py2neo.
If you are happy setting the color through a graphical user interface rather than programatically, Neo4j also supplies a data exploration addon named bloom. When using this addon (now automatically installed when using neo4j desktop), it is possible to set node color based on its properties.
In the example below, movies released after 2002 are colored green.
I'm using Neo4j Community edition 2.1.4. I have hierarchy of 4 levels and each level names i have treated it as label name for that level.So in my graph i have totally 4 labels. Now for the first time I have loaded csv file into neo4j and using MERGE and CREATEkeywords created the nodes and relationships. In future the requirement is like
scenario 1:
if someone wants to rename the hierarchy level name to some new name, then I have to
change the label name to a new name.
Scenario 2:
if any of the property name of node changes to to new name
In the both the cases i wanted to track the history of the node. How can i do it? So that in future someone wants to see the history details , they can query and get the details.
So how can i track the history details of the nodes in neo4j?
My Approch:
For the first time i will load the csv file and create nodes and relationships. Then if someone wants to change the label name of node A(level name which is standard) which is having a properties like ID, name,start_date,end_date,Status.Then i will replicate the node A with all the properties and change the status to inactive and i will overwrite the old node with the new details. But i'm clueless whether this solution is going to work or not. Also i have more thane 10000 nodes in my db.
So please suggest me a better approach to track the nodes history.
Have a look at the GraphAware ChangeFeed Module. You can track history of changes and also configure which changes you would like to track and which to ignore.
You can use versionning. Examples in this blog post : neo4j.org/graphgist?608bf0701e3306a23e77 that you can adapt for your needs
I need to write batch importing utility for my Neo4j database but I don't want to lose the repository feature of SDN. To achieve this goal I want to insert such nodes that can be still queried using auto generated repository methods.
I inserted some nodes to my database and I looked at their properties and labels to see how they are set and I noticed that SDN inserted nodes have two labels. For example nodes representing class SomeClass have labels: ["_SomeClass", "SomeClass"]. My question is: why set two, almost identical labels for each node?
Oh that's actually simple. We somehow have to note if the current node is of type SomeClass, which we do by prepending the "_". As there are labels added for each super-type you need to differentiate what the actual type of the node in Spring Data Neo4j is.
So you could have: _Developer, Developer, Employee, Person for a class hierarchy from Person down to Developer. And then there could be additional labels for interfaces.
When you now do: DeveloperRepository.findAll() then you only want those with _Developer back, not ones that derived from Developer.