I am trying to find out what are the sequences belong to above mentioned entities. I would be grateful if someone find me because i tried finding them in dependencies, inside the triggers and in API without luck
Search in Oracle docs. They give specification of each table in detail
Related
We are working on a system where users can define their own nodes and connections, and can query them with arbitrary queries. A user can create a "branch" much like in SCM systems and later can merge back changes into the main graph.
Is it possible to create an efficient data model for that in Neo4j? What would be the best approach? Of course we don't want to duplicate all the graph data for every branch as we have several million nodes in the DB.
I have read Ian Robinson's excellent article on Time-Based Versioned Graphs and Tom Zeppenfeldt's alternative approach with Network versioning using relationnodes but unfortunately they are solving a different problem.
I Would love to know what you guys think, any thoughts appreciated.
I'm not sure what your experience level is. Any insight into that would be helpful.
It would be my guess that this system would rely heavily on tags on the nodes. maybe come up with 5-20 node types that are very broad, including the names and a few key properties. Then you could allow the users to select from those base categories and create their own spin-offs by adding tags.
Say you had your basic categories of (:Thing{Name:"",Place:""}) and (:Object{Category:"",Count:4})
Your users would have a drop-down or something with "Thing" and "Object". They'd select "Thing" for instance, and type a new label (Say "Cool"), values for "Name" and "Place", and add any custom properties (IsAwesome:True).
So now you've got a new node (:Thing:Cool{Name:"Rock",Place:"Here",IsAwesome:True}) Which allows you to query by broad categories or a users created categories. Hopefully this would keep each broad category to a proportional fraction of your overall node count.
Not sure if this is exactly what you're asking for. Good luck!
Hmm. While this isn't insane, think about the type of system you're replacing first. SQL. In SQL databases you wouldn't use branches because it's data storage. If you're trying to get data from multiple sources into one DB, I'd suggest exporting them all to CSV files and using a MERGE statement in cypher to bring them all into your DB at once.
This could manifest similar to branching by having each person run a script on their own copy of the DB when you merge that takes all the nodes and edges in their copy and puts them all into a CSV. IE
MATCH (n)-[:e]-(n2)
RETURN n,e,n2
Then comparing these CSV's as you pull them into your final DB to see what's already there from the other copies.
IMPORT CSV WITH HEADERS FROM "file:\\YourFile.CSV" AS file
MERGE (N:Node{Property1:file.Property1, Property2:file.Property2})
MERGE (N2:Node{Property1:file.Property1, Property2:file.Property2})
MERGE (N)-[E:Edge]-(N2)
This will work, as long as you're using node types that you already know about and each person isn't creating new data structures that you don't know about until the merge.
First of all, I bet that there is an answer on this question somewhere in docs, but since 'Manual: Labels and Indexes' link here gives me 404 error, I'm going to ask you anyway.
Is it possible to create an index on some label and specify it as an automatic one (just like legacy indexes I'm currently using, but for labels)?
If someone from neo4j team is reading this post, please let me know if I'm looking for the documentation in the right place, 'cause I can't find anything more or less informative on labels and indexes (except a couple of posts in Michael Hunger's blog and, maybe, some presentations, what is obviously not enough).
This is a more technical one: is it possible to find an item in the index by the regex? Suppose I have node with property 'n' -> '/a/b/c', and another node 'n' -> '/a/*/c. Can I somehow match them?
I don't work for Neo4j but I'll answer anyway.
All label indexing is automatic. Once you've created the index it maintains itself, possibly with minimal delay.
The manual for the last stable release can always be found here. The chapter on indexing for the embedded Java API is here.
You cannot use regexp with label indices yet. It's said to be on the agenda, along with index support for array lookups, i.e. what in Cypher would be
MATCH (a:MyLabel) WHERE a.value IN ['val1', 'val2']
I need some advice please, I have been looking for help on this topic but it's not something you find so often. I am also quite new to Zend, so please excuse my terminology
I have a few large sql queries coming up. Most of my other queries are quite small, just a couple of joins etc, but these ones consist of many queries (drop and create temporary tables which together form the final select.) For example
DROP table if exists tmp_abc;
CREATE temporary table tmp_abc as SELECT .... From ... Group By //finish statement
Consider 20 other of these, then a final select which pulls a lot of data from one table.
Can anyone offer some advice on the best solution to tackle this problem?
Would this be possible using some RAW sql adapter or? ... I am kinda of tempted to sod the MVC principle for this based on the complexity/size of the query, but it is something I would like to know for the future which action I should go.
One possibility is to do most of it on database level, some stored procedure(s)/maybe view or two if needed. And then select from that.
This question is about why I would use the above keywords. I've found plenty of MSDN pages that explain how. I'm looking for the why.
What query would I be trying to write that means I need them? I ask because the examples I have found appear to be achievable in other ways...
To try and figure it out myself, I created a very simple entity model using the Employee and EmployeePayHistory tables from the AdventureWorks database.
One example I saw online demonstrated something similar to the following Entity SQL:
SELECT VALUE
DEREF(CREATEREF(AdventureWorksEntities3.Employee, row(h.EmployeeID))).HireDate
FROM
AdventureWorksEntities3.EmployeePayHistory as h
This seems to pull back the HireDate without having to specify a join?
Why is this better than the SQL below (that appears to do exactly the same thing)?
SELECT VALUE
h.Employee.HireDate
FROM
AdventureWorksEntities3.EmployeePayHistory as h
Looking at the above two statements, I can't work out what extra the CREATEREF, DEREF bit is adding since I appear to be able to get at what I want without them.
I'm assuming I have just not found the scenarios that demostrate the purpose. I'm assuming there are scenarios where using these keywords is either simpler or is the only way to accomplish the required result.
What I can't find is the scenarios....
Can anyone fill in the gap? I don't need entire sets of SQL. I just need a starting point to play with i.e. a brief description of a scenario or two... I can expand on that myself.
Look at this post
One of the benefits of references is that it can be thought as a ‘lightweight’ entity in which we don’t need to spend resources in creating and maintaining the full entity state/values until it is really necessary. Once you have a ref to an entity, you can dereference it by using DEREF expression or by just invoking a property of the entity
TL;DR - REF/DEREF are similar to C++ pointers. It they are references to persisted entities (not entities which have not be saved to a data source).
Why would you use such a thing?: A reference to an entity uses less memory than having the DEFEF'ed (or expanded; or filled; or instantiated) entity. This may come in handy if you have a bunch of records that have image information and image data (4GB Files stored in the database). If you didn't use a REF, and you pulled back 10 of these entities just to get the image meta-data, then you'd quickly fill up your memory.
I know, I know. It'd be easier just to pull back the metadata in your query, but then you lose the point of what REF is good for :-D
I'm very interested in building a data visualisation component and can
see how it could be done but would prefer not to reinvent something
which already exists. If this truly is a 'first' then I'm prepared to put my initial code
on Github for others to share [and hopefully improve !!]
Essentially I'd like to be able to do the following:
1) Access a table or tables within a database and create nodes based
on entries within them. Add nodes on create, remove them on delete.
2) Use the foreign keys and/or join tables [for many-many links] to
create edges. Add edge(s) when node created, remove edges when node
deleted, check and add/remove edges when node updated.
3) Pass the nodes and edges to Gephi for display
I can see how to do steps 1 and 2 quickly and easily -- what I haven't
been able to find (after much searching) is how to do step 3.
Has anyone had any success in doing this? -- any example code that they're willing to share ?
Thanks
We tried something similar once, but it may not help you that much. We wrote a Rake task that got data out our DB, which we then fed into Gephi manually. That wasn't really satisfactory and in the end I went with Rake task -> CSV -> R script for visualization (basically connections of users on a world map). If you are not dead set on using Gephi I could show you some of the R code :-)