I'm implementing a multi-tenancy capable application based on Java 8, Spring Boot 2 and JPA/Hibernate 5
There are different approaches to this, I chose the schema based approach. The Hibernate docs also write about support for this.
I also looked at some tutorials
But it seems like everyone on the net uses native SQL to switch schema. Not only do I have to support multiple DBMS - but I could provide different implementations - but it seems like MS SQL Server does not support setting a schema for the duration of a connection only.
There is a setSchema(String) method on the JDBC Connection object, but MS does not support it (also verified by looking at their source on Github). Not only that, but I can't find a way using T-SQL either.
Is there another way to set the connection schema in my ConnectionProvider, or do I have to switch to a completely different approach (e.g., discriminator column based)?
FYI, the schemas have to be dynamic, since tenants can be created via the UI.
IMHO, the best multi-tenant strategy for your application requirements, would have been COLUMN DISCRIMINATOR strategy ... But it's still under development and not available with the last Hibernate 5.3.2 release.
FYI, the schemas have to be dynamic, since tenants can be created via the UI.
Using schema strategy with this high portable requirements is very hard to implement for some reasons:
Schema concepts are very different across database vendors
Hibernate multi-tenant solution is yet very light
I suggest, you lower your portable requirements and choose only database vendors giving you the tools for effective multi-tenant schema strategy.
Related
I'm currently developing a Node.js app that needs to be able to switch between PostgreSQL and SQL Server databases. Both databases have identical tables and the operations will also be identical (basic CRUD, nothing fancy).
I've done research, and know that there are enough libraries around to access both databases.
Ideally I'd like to use a ORM and just let that handle the differences. However, I can't seem to find an ORM framework that does both. In fact, I can't locate any ORM that supports SQL Server, while almost all support Postgres.
So my question: is there an ORM that supports both? And if there isn't, are there other abstraction tools/frameworks around that will make my developer life easier?
There is a certain amount of YAGNI here, but if you are unable to find an ORM that supports both, your next best bet is to just use an Adapter Pattern and ensure you're not using the ORM directly in your code, but through a wrapper. Then if / when you need support for SQL Server, you can create the implementation for the wrapper which will replace the PostgreSQL implementation.
We have an application that requires our customers to have a SQL server instance on site. At their request, the application needs to synchronize the data in their database with a copy in our datacenter.
We're using .Net 3.5 SP1. We need to synchronize the data exactly, including IDENTITY columns.
We'd prefer to use something like LINQ to SQL that would let us make some simple select and insert/update calls against mapped entities. However, the IDENTITY columns seem to be a problem with LINQ and similar approaches.
We can do this all with built-up SQL statements and turn IDENTITY INSERT on / off as needed, but I'd prefer a more elegant solution.
Thanks!
** Edit - We DO need to write our own solution, and we do need to use .Net 3.5 SP1 to do it. I won't spend your time explaining all the reasons why, but please limit suggestions to options within the .Net playground.
Microsoft Sync Framework can be your solution. This is framework description from Microsoft:
Microsoft Sync Framework is a data synchronization platform from Microsoft that can be used to synchronize data across multiple data stores. Sync Framework includes a transport-agnostic architecture, into which data store-specific synchronization providers, modelled on the ADO.NET data provider API, can be plugged in.
Sync Framework is a comprehensive data synchronization solution that enables developers to build solutions that support synchronization of any database, on any data protocol over any network topology. msdn.microsoft.com
For your convinience providing link to good tutorial on the subject
If it is just a couple of tables that need to be synchronized and there is not a lot of data in the tables (now and future) you could develop some sort of bulk copy from your servers and bulk insert routine on the customer's server.
Since you said you can't use SQL Server replication services or SSIS, then perhaps a backup/restore procedure could be written. You could take a scheduled backup of your database and make it available to calling applications which could then copy the backup, restore it to another instance on the customers server, then pull all data you need via any number of methods and it would exist locally on the customers servers.
Beyond that, I think you may be asking for a maintenance and synchronization nightmare if you can't base your solution on tools that are made to do this sort of thing.
I'm going to develop a Web Application with two essential requirements:
Total independence of DBMS. The application should work with different DBMS like Oracle, SQL Server and MySQL. That is, Client 1 use this application with SQL Server, but he wants to migrate to an MySQL Database. The application should be able to work with this new DBMS without needing to make changes to the application code. The only change I want to do is to change the connection string.
Scalability. ie, we will have a clustered SQL Server installation.
I know that Data Access Block is able to handle different DBMS and I assume it won`t be an issue to meet the scalability requirement, but I don't know if this is the case with Entity Framework.
Choose Entity Framework, for a couple of reasons.
First, EF is where Microsoft is putting all its data access emphasis for the foreseeable future. Entlib's data block is primarily there to support folks already using it.
Second, Entlib will give you a regular API, but it doesn't insulate you from the differences in SQL statements. Oracle in particular does stuff with cursors no other database does (or needs to); EF at least attempts to give you a uniform API.
As far as scalability, that's all about the design of your database and application, no data access tool will give you that.
Our IT manager is asking my help on deciding on which would be the best to save the data. Is it in sharepoint or sql server.
On my side I don't know much about saving data on sharepoint server, how does it work, how fast, how secured, etc. I even have a doubt if sharepoint is capable of complex database design. As far as I know, sharepoint is not a database server that's why I have this doubts.
So obviously I would say Sql Server would be my prefered storage and also because Sql server is known to me for a long time already. Considering my 3 weeks exposure on sharepoint vs. 7 years on Sql Server. I don't have the enough experience to witness the strength of Sharepoint for me to decide on what to do. So to be fair on sharepoint I would like to ask you guys out there who are more experienced on this.
My questions:
1.) Does sharepoint have the ability to store data?
2.) If sharepoint can store data, what are the pros and cons?
3.) Can it cover a complex design such as relational database design like sql server does?
4.) If you where to develop a sharepoint project, would you choose sql server as the backend?
Thanks in advance!
It obviously depends on the application, and complexity of it, who the client or audience is, and how you want to deploy it.
Here are my answers to your questions:
1. Yes
2. Pros:
It provides a UI for updating data.
Cons:
Creating relational structures will be complicated.
Think custom lookup lists, associated with other custom lists.
3. Yes, but I wouldn't try it.
4. SQL Server, but this depends on the project and
isn't an entirely technical decision.
Personally, I think given your skillset, you should use SQL Server, if your manager has said it's up to you.
SharePoint itself is built on top SQL Server and ASP.NET.
Yes. You can create a custom list (basically similar to table structure), you can store document along with its metadata. You can store web pages if you are using it as your publishing (CMS) platform.
It's not supposed be a relational engine like SQL Server. Pro: versioning, workflow, for most cases, UI is there to support data input / editing. Con: Limitation of the UI w/ large amount of data.
To some degree you can relate one list to another field in a different list / document metadata.
See what I said before point 1.
SharePoint offers its own database layer built on top of SQL Server.
A complex object model is provided, and the SQL language API not available.
Acsess is by API, REST, and UI List Webparts with views; NOT SQL and the database is not accessible except through interfaces.
Deep inside data stored in Entity-Attribute-Value triples (specifically: site, web, list, item, state, field, value) such that each value goes into its own record. This is strickly non-tablular.
Maintains a dynamic end-user populated Metadata dictionary.
As a non-relational layer above a DB is offers inheritance, multi-type list, hierarchies, taxonomies, versioning, check in/out and other advanced features missing from a relational model.
Documents may be attached to a list.
Extensive use of GUIDS for identifiers, but this causes problems when moving partial related data between systems.
No referential integrity.
No joining of database tables or lists.
Filtering is more limited than in SQL.
No concept of a schema.
Parts of SharePoint break when restoring from a backup or when published to a separate site.
Rolling new features and data from development to production is problematic and sometimes breaks.
Hope this helps.
Sharepoint is obviously not a Database Server but somehow it works on some ways.
1.)Yes
2.)You can but not as complicated as Sql Server does.
Pros: It's the interfaces the gives sharepoint the edge, UI grants the user a friendlier way of inputting data.
Cons:Just like what I've said complicated database design is not easy to do.
3.) 100% Yes
4.) I would prefer Sharepoint if the application doesn't need complex design on data. Definitely Sql Server for enterprise type of application.
Our client wants to support both SQL Server and Oracle in the next project. Our experience comes from .NET/SQL Server platform. We will hire an Oracle developer, but our concern is with the DataAccess code. Will NHibernate make the DB Engine transparent for us? I don't think so, but i would like to hear from developers who have faced similar situations.
I know this question is a little vague, because i don't have Oracle experience, so i don't know what issues we will find.
You can easily use NHibernate to make your application database-agnostic by following some basic practices:
Design your object model first.
Do not use any database-specific code. You need somebody with good C# experience, not an Oracle developer. Do not rely on stuff like triggers, stored procedures, etc.
Let NHibernate generate the DB schemas at least initially (you can tweak things like indexes later) It will choose the best available datatypes for each DB.
Use a DB-agnostic POID generator (hilo or guid) instead of sequences or identity.
Try to avoid using SQL. HQL and Linq work fine in 99% of the cases.
Avoid NH features that are not supported by all of your target DB (for example, Future, MultiCriteria, etc)
NHibernate has a great community. You can always ask your questions in http://groups.google.com/group/nhusers besides posting here.
There are three things to consider - the ISession object, the SQL queries that are generated and your plain-old-clr-objects that are mapped to tables.
NHiberante will generate the required SQL queries based upon the chosen database dialect. If you configure NHibernate to use the SQL Server dialect it will generate SQL server correct SQL statements. This can easily be configured dynamically at runtime based on configuration.
You also need to configure your session to connect to the right type of database. Again, various configuration methods can support dynamic ISession creation at runtime.
Your actual data objects which are mapped to tables should not need to change based on database choice. One of NHibernates strengths is flexibility it provides in supporting multiple databases via a (fairly) simply configuration change and some up-front architectural thought.
See http://codebetter.com/blogs/karlseguin/archive/2009/03/30/using-nhibernate-with-multiple-databases.aspx for some examples of how you might abstract the underlying database away from the creation and usage of NHibernate.