Firstly, let me start by saying that I haven't ever directly used SQL views. I don't know if they are an antiquated thing, or if they're the right way to do things in this arena. Which of the 2 methods do you prefer when considering security (don't show Acme's credit card number that's on file to a WidgetCorp user, etc), and are there other important considerations besides security?
I use it for
Security purposes like you described
In sub queries. Helps to keep my queries more compact, efficient with indexed views and also if I find myself reusing the same sub-query them I just make it into a view.
Here something to read.
Related
I was reading at this article https://www.infoq.com/articles/spring-data-intro to understand how can a data service layer be independent of database(RDBMS /NoSQL). It looks like there's no way to design entity and repository to be independent of database. This article was written on 2012. Do we've any other technologies since then that has implemented this feature?
Before actually answering your question I have to ask: Why do you want to do that? Think twice because abstraction comes at a cost and just doing it in order to have a "clean" design is most certainly not worth it.
Now to your question:
There is no library or framework that does this out of the box.
Probably the thing getting closest to it is spring data which you are obviously aware of. If you stick to the persistent storage independent interfaces your repositories will abstract over the persistence store use at least to some extent. BUT: you will have to provide different kinds of metadata (typically as annotations on the entities) to make it work. So in this sense, it is a really leaky abstraction.
Of course, you can roll your own: create an interface with the operations you need and provide implementations for the different data stores you want to use. Also, include a storage independent way of providing metadata.
So the question becomes: Why hasn't anybody done that yet? And why you probably shouldn't do it either?
It is hard: Just writing SQL in a way that all (relevant) SQL databases understand is difficult, see this for an example.
You loose a lot of power of your stores. For example, RDBMSes are great at joining stuff. But joining is basically a no go for many No-SQL databases. So your API probably shouldn't offer this feature. This basically dumbs everything down to the common denominator, which is going to be really small when you have very different data stores.
It is not worth it. This leads back to my opening question: Why would you want to do it anyway? I certainly see the use of switching different RDBMSes. Some companies only want certain vendors in their datacenter, it is nice to have an in memory variant for testing and so on. But switching a store from for example Oracle to Hazelcast and then to MongoDB to CSV? Why would you want to do that? What is the business value of that?
Hi thank you for the help in advance,
I have looked at some of the posts and I am a bit confused about the multi threading. It seems that it may be pretty easy, however I am very new to programming so I am still trying to grasp this.
These are two calls to pull data from a database, and they take forever as it is... So I'm thinking about multithreading these until I can learn how to build a core data for this. Right now i am using sqllite and the database involves 10,000 + recipes... So not lightning fast like I would like...
Please let me know what you think, and how I can make these happen maybe simultaneously? (If thats even possible)
Thank you in advance.
requestCount++;
[[DataPuller sharedDataPuller] getAllDeletedRecipeList];
[DataPuller sharedDataPuller].target = self;
requestCount++;
[[DataPuller sharedDataPuller] getAllRecipesList];
[DataPuller sharedDataPuller].target = self;
If you're doing SQLite, you might want to contemplate using FMDB which (a) gets you out of the weeds of sqlite3 calls; and (b) offers a FMDatabaseQueue which allows you to coordinate queries from multiple queues, so that the data operations don't stumble across each other.
Having said that, you suggest that you're having significant performance issues which you're hoping to solve with a shift to Core Data or going multi-threaded with SQLite. That's unlikely. Poor performance of local database operations is generally more of a matter of your application design (e.g. it's unlikely to be wise to try to retrieve the entire details for all 10,000 recipes ... you probably want to retrieve just the unique identifiers, perhaps only those required for the given screen, and then only retrieve the particulars for a given recipe at a later point as you need that). For local database interaction, you rarely have to contemplate a multithreaded implementation, but rather just design the system to retrieve the least possible information at any given point that you need for the presentation. I personally find that my database-driven apps generally only need to go multithreaded when I'm doing extensive interaction with some remote web service (in which case, it's the retrieval of server data and the parsing of that which goes on the separate thread, not necessarily the database operations themselves).
If you're having performance issues with your recipe app, I'd suggest you submit a far more detailed question, with code samples, that articulates your particular performance problem. And I wouldn't be surprised if multi-threading was not part of the solution. Likely, appropriate use of indexes and a more judicious retrieval of information at any given point might be more critical.
Get records from database in the form of pages; i.e. 20 or 50 recipes per page. Have a look on YouTube app. on iPhone or have a look on my app. HCCHelper
I know this topic was discusses a couple of times, but none of them represents the ultimate solution for me.
Situation
I'm designing a relational mysql database which later should hold multilingual content. You know this from the Wikipedia or Microsoft Tech Support Pages. The contents should be the same for every language. e.g If translations are missing the site offers you the same content automatically translated or in the languages which the information is available in. If some values are not set, it should fallback to the second or default browser language or translate it e.g. through google. Development environment is Zend.
My ideas so far are for Solving the Problem:
Two Primary Keys: (ID, Language)
Advantage: Easy Database Access through database abstraction layers.
Problem: Foreign Keys, Relations ships, Fallbacks
Columns with language suffix:
Advantage: DB Performance, No relational Problems.
Problem: Database abstraction layers cannot handle this?
Has any concept proven itself or is preferable over the other? Has anyone already created something like this and can share his experience with me? Does a modified Zend DB Controller exist for this situation? How do you link this information to a form?
Thank you for your help, hints and suggestions!
Kind regards,
Manuel
The second option would be not maintainable (this should be added on the minuses side). To actually add another language you'll need to modify table and abstraction layers. Sounds like a nightmare.
The first option seems much more promising but unfortunately there is a lot to do to make it work. However, from my experience this is rather typical solution, so I would not reinvent the wheel.
What I have to add is, language fallback should be done on the Zend side, database would miss some information. You may think of some kind of index table to hold information such as unique id of the contents and available languages. If you need to serve something, you would read such record, compare it against of Accept Languages and ask database again for valid contents (using the most suitable language). The only problem is, you would need to create such an index table somehow (the best way I see would be trigger on inserting contents to your content table).
A lot of work but the problem is not too easy.
I am working on the exact same problem right now.
Somehow it does not make sense to me to add everything into the same database. Lets say I want to go to the extreme and support some 50 languages this would just bloat my DB. So, I tend to keep my main DB in my main language and then introduce some Zend_Translate concept into it. Zend_Translate should give you the fallback solution you are looking for. While the main navigation and core design is not much of a problem for my web site my biggest concern right now is how to store all the main content and how to translate because these elements contain HTML among other things. For the main content I will probably use some alternate approach and use a separate DB with tables for each language.
My plattform will be a community driven database. So I actually gonna rely on humans translating it. You have to store the information anyways, so my first concern is not the database size or performance, but easy usability. So far my idea is to implement some structure as described above, not yet sure if i'll do it in doctrine or not.
Language decision:
Start, application gets users preset language, secondary language, english mother-tong of the article. Fetching the article from the database I will check the following for every column: 1. is the primary language available? 2. Is the secondary language available? 3. If neither of them, display article in mother-tong or english and offer the user to translate it with suggestions from the google translate api. I guess it's gonna be quite a bit of coating and manipulating controllers or building a business model doing this.
#tawfekov is something like this or similar easily realizable with doctrine?
I'm working on a simple eCart system using .net4 (c#). I've been doing a lot of reading about Unit of Work Pattern, Repository Pattern, and Persistence Ignorance. I think I have a grasp on the strategy and benefits to building my layers this way, but for my simple app I'm wondering if it's necessary and if anyone can point me towards good architecture for my scope.
Please correct me if I'm wrong - the main benefits to using repositories are to create fewer trips to the DB and to separate application architecture from DB architecture. IE - what's good for DB performance isn't always good for application design so it's best to design what's best for both and then create an interface between the two.
So here's the question - I want any business transaction that occurs to be saved to the DB as soon as it occurs, so there doesn't seem to be a point in queuing data in repositories and then saving it immediately. Why not just save it directly?
Are there other benefits of DDD that I'm missing or would it be over engineering to build out such a robust architecture for every simple project that comes along? Thanks for any help.
Do you need to use [insert pattern here]: Nope When it comes right down to it, the best practice is always the one that gets your application done, and meets the time, monetary, and technical requirements.
But if you take the "lets just get it done" approach, then be aware of the Technical Debt you might be incurring.
Also there are a lot of reasons to use some of these patterns (and they don't always have to do with performance), particularly the Unit Of Work pattern. This has more to do with the requirements and restrictions that often come with ORM's and such. These issues can be a bit complex, but I suspect as you begin to implement some of these things you'll start to realize what those issues are and come to understand why these patterns are useful.
Agree with CodingGorilla. Patterns are great unless they conflict with YAGNI.
If every transaction needs to be written immediately (that is, if you have potential contention between the actions of two users) then you will need a queuing mechanism or you can use the underlying transactional mechanism of whatever data repository you might be using (e.g. SQL)
The queries that i create frequently have 7-8 joins to retrieve data. Are these many joins normal in a real database application or is my database design poor? I am curious because if on each request database has to do so much work, then won't it die if few thousands of client connect?
In my opinion it's inevitable in some cases, the key is to have the correct indexes for the queries you're doing. With a deep object graph in ORM, or perhaps one with joined subclasses, it'd be easy to go over the 7-8 joins you talk of. I'm keen to hear what everyone else has to say about it :)
Its not possible to draw a Conclusion in this regard without the Application Logic Details.
If your Application Logic leads you to unavoidable joins to maintain the integrity Its not a Problem, and Your Database Platform must handle it.
That is a lot of joins. It's hard to say without seeing your schema, but I have seen cases where people have gone nuts making a schema overcomplicated. I remember one application I worked on where every address and phone number in the system was treated as an entity, and queries frequently involved joins of over a dozen tables. You should be careful when making a schema to distinguish between those things you care about individually tracking and everything else, otherwise you can end up with needless complexity.