How is the performance of a Stored Procedure? Is it worth using them instead of implementing a complex query in a PHP/MySQL call?
Stored procedures will give you a small performance boost, but mostly they are for doing tasks that are difficult or impossible to do with a simple query. Stored procedures are great for simplifying access to data for many different types of clients. Database administrators love them because they control how the database is used as opposed to leaving those details to the developer.
Look to indexes and proper table design to get better performance.
Yikes I'd hate for someone to read these answers and get the wrong impression. There are some really important differences between the "Stored Whatever" implementations on "MySQL" vs "SQL server/Oracle".
See: http://www.joinfu.com/2010/05/mysql-stored-procedures-aint-all-that/
Every person that asks this question assumes something about MySQL’s
stored procedure implementation; they incorrectly believe that stored
procedures are compiled and stored in a global stored procedure cache,
similar to the stored procedure cache in Microsoft SQL Server[1] or
Oracle[2].
This is wrong. Flat-out incorrect.
Here is the truth: Every single connection to the MySQL server
maintains it’s own stored procedure cache.
Take a minute to read the rest of the article and comments. It's short and you'll have a much better understanding of the issues.
As was pointed out to me in a previous answer courtesy of JohnFX:
"The performance benefit of stored
procedures is dubious and minimal at
best. Some reading material on this
point:
http://statestreetgang.net/post/2008/04/My-Statement-on-Stored-Procedures.aspx
http://betav.com/blog/billva/2006/05/are_stored_procedures_faster_t.html
Enjoy.
Grossly simplified -
Stored procedure performance is equal to or marginally better than code at the cost of db server load. Since most db systems are concerned with multi-user access and are using commodity hardware for the db server, using code offloading the db server will probably win overall. With high end DB servers, > 4 cores, > 32gb ram, SP load is often not an issue.
Stored procedures;
transfer less data in the query - minimal speed improvement for well written code
parsing & caching is "slightly better" - minimal speed improvement for well written code
move the execution load to the db server vs. client(s) (web servers), potentially spreading the load over many systems. - speed improvements are very dependant on the actual code and amount of data including "excess" data transferred. Quite a bit of code transfers more data than is actually used (db libraries, poorly written queries, select *, etc.)
Don't optimize early.
Stored procedures have many other benefits than speed, security being high on the list.
In a single programmer environment, benefits may be offset by SP programming learning curve, SP testing framework, multiple methods of revision control - SP and code, etc..
Learning and using a testing and profiling framework will answer this definitively and will guide you in providing better "performance" to your app than simply choosing SP or ad-hoc queries.
Answer to "is it worth it" - If you don't have a testing/profiling framework in place you'll only be guessing. Any answer based on my code and hardware is probably irrelevant on yours.
My real world experience on many Perl/TCL/PHP/C web apps using DB's (Sybase,Oracle,MS SQL,MySQL,Postgres) stored procs DO NOT greatly improve performance over all. But I still use them often, just for other reasons than performance. They can greatly improve a specific complex query, but that's rarely the bulk of the code and overall processing time.
In MySQL or any other SQL server as MSSQL or Oracle, stored procedures increase dramatically the speed of the queries involved because this are already compiled. Stored procedures are more secure than direct queries and as object in the database they can be administered by the owner, giving the right access to each user.
Using stored procedures you can also hide the logic of the queries and procedures and give to the development team and other programmers a "black box" in wich they insert params and receive results.
Definitively stored procedures rocks!!!!
From MySQL 5.1 Documentation:
Stored routines can be particularly useful in certain situations:
When multiple client applications are written in different languages or work on different platforms, but need to perform the same database operations.
When security is paramount. Banks, for example, use stored procedures and functions for all common operations. This provides a consistent and secure environment, and routines can ensure that each operation is properly logged. In such a setup, applications and users would have no access to the database tables directly, but can only execute specific stored routines.
Stored routines can provide improved performance because less information needs to be sent between the server and the client. The tradeoff is that this does increase the load on the database server because more of the work is done on the server side and less is done on the client (application) side. Consider this if many client machines (such as Web servers) are serviced by only one or a few database servers.
Stored routines also allow you to have libraries of functions in the database server. This is a feature shared by modern application languages that allow such design internally (for example, by using classes). Using these client application language features is beneficial for the programmer even outside the scope of database use.
Related
When I first got into databases I was using SQL Server. I got into that originally with classic ASP. One of the big things we were told was that you saved a LOT of time in your SQL transactions if you used stored procedures, rather than working with the ASP SQL commands (doing it "in line", I suppose). So almost everything I ever wanted to do with the database I wrote a stored procedure for, and then called the stored procedure from my code.
Anyway, fast forward several years and I'm now doing all of my work with PHP and MySQL (and a little Python). One thing that I don't seem to see much of at all is people using stored procedures/functions, so I haven't really been worrying about it.
However, it occurs to me that I'm just doing it wrong and don't realize it. Is there a major advantage to using stored functions in MySQL? I'm building a fairly good-sized website that handles a lot of calls to the database. The calls are all done in-line with my PHP code. Would I be better off using stored functions for the calls that I'm making consistently, and then just passing variables to the function from the PHP?
Well that depends. Stored procedures are a way to handle functional decomposition and can be absolutely essential if you have multiple applications interacting with the same database. The idea of using stored procures for everything was on the ascendancy a couple of years ago and as the world has moved to a service/RAD world they are losing some ground.
Some of the benefits of stored procedures are
Reuse / This can certainly be accomplished within your code base but it beats the hell out of writing the same query with 10 sub joins 15 times
Security - when sp were the rage sql injection attacks were coming to the for front and one way to reduce your exposure is to offer parameterized sp that sanitize you input automatically for the most case
Documentation by definition on really large databases table layout is not always sufficient to explain what you are storing and why and have SP sometimes gives you and those that come after you what was intended
A defined interface.
I think that all of these pros can be provided assuming good application design and only make scene to a degree on projects of some scale.
Some cons
Redundant functionality - I have seen a lot of shops where business and crud logic is spread in the application and business logic is in the database.
Lack of configuration management on SPs -- While there are established procedures and tools for code SP management lags far behind.
This is the same question as asking, "Should I break up my code into methods/functions/procedures and call them or should I code everything into my current function?"
Some of the advantages that stored procedures give you:
Easier testing. You can test the stored procedures without running the app.
Easier development. You can have a DB developer write the stored procedures and a GUI developer write the UI, etc.
Easier porting to a different database. The changes are all contained in the database and the contract with the app (The parameters passed to the stored procedures) should not change.
The ability to use the logic in the stored procedure from multiple front ends. You do not have to code the same customer create logic in every app that needs to create a new customer.
The big downside is that you have to learn multiple diciplines and probably use multiple tools. This is one of the big reasons for using Linq for SQL in .Net. You do not have to learn SQL and everything is contained in the .Net code.
We use stored procedures for everything. It works exceptionally well. Abstraction is your friend.
I'm the webmaster for a major US university. We have a great deal of requests on our website, which I've built and been in charge of for the last 7 years or so. I've been building ever-more-complex features into our website and it's always been my practice to put as much of the programming burden on our multi-processor Microsoft SQL server as possible - using stored procedures, views, etc, and fill-in what can't be done with PHP, ASP, or Perl from the IIS web server. Both servers are very powerful and capable machines. Since I've been doing this alone for so long without anyone else to brainstorm with, I'm curious if my approach is ideal for even higher load situations we'll have in the future.
My question is: Is it better practice to place more of the load burden on the SQL server using nested SELECT statements, views, stored procedures and aggregate functions, or should I be pulling multiple simpler queries and processing through them using server-side compile-time scripts like PHP? Keep on keepin' on or come up with a better way?
I've recently become more interested in performance after I did some load traces and learned just how much I've been putting on the shoulders of the SQL server. Both the web server and SQL servers are fast and responsive throughout the day, and almost without regard for how much I put on them, but I'd like to be ready and have trained myself and upgraded my existing code optimized best practices in mind by the time it becomes important.
Thanks for your advice and input.
You put each layer in your stack to use in the domain it fits best.
There is no use in having your database server send 1000 rows and using PHP to filter them if a WHERE-clause or GROUP-clause would suffice. It's not optimal to call the database to add two integers (SELECT 5+9 works fine, but php can do it itself, and you save the roundtrip).
You will probably want to look into scalability: what parts of your application can be divided unto multiple processes? If you're still just using 2 layers (script & db), there is a lot of room for scaling there. But always start with the bottleneck first.
Some examples: host static contents on CDN, use caching for your pages, read about nginx and memcached, use nosql (mongoDB), consider sharding, consider replication.
My opinion is that it's generally (mostly) best to favor letting the web servers do the processing. Two points:
First is scalability. Once your application gets enough usage, you'll need to start worrying about load balancing. And it's a lot easier to drop in a couple of extra web servers pointing to a common database than it is to set up a distributed database cluster. So best to take as much strain away from the Database as you can and keep it on a single machine for as long as possible.
The second point i'd like to make is about optimizing the queries. This will depend a lot on the queries you are using, and the database backend. When i first started working with databases, i fell into the trap of making elaborate SQL queries with multiple JOINs that fetched exactly the data i wanted, even if it was from four or five different tables. I reasoned that "That's what the database is there for - lets get it to do the hard work"
I quickly found that these queries took way too long to execute, and often ended up blocking the database from other requests. While it may seam inefficient to split your query into multiple requests (for example in a for loop), you'll often find that executing multiple small queries with fast indexes will make your application run far more smoothly than trying to pass all the hard work to the database
Firstly, you might want to check if there is any load which can be removed entirely by client side caching (.js, .css, static HTML and images), and use of technologies such as AJAX to do partial updates of screens - this will remove load on both web and sql servers.
Secondly, see if there is sql load which can be reduced by web server caching - e.g. static or low refresh data - if you have a lot of 'content' pages on your systems, have a look at common CMS caching techniques which will scale to allow many more users to view the same data without rebuilding the page or hitting the database.
I tend to do as much as possible outside the db, viewing db calls as expensive/time-intensive.
For example, when performing a select on a user table with fields name_given and name_family, I could fatten the query to return a column called full_name built by concatenation. But that kind of thing can be easily done in a model on your server-side scripting language (PHP, Ruby, etc).
Of course, there are cases when the db is the more "natural" place to perform an operation. But, in general, I incline more towards putting the load on the web server and optimize there with many of the techniques noted in other answers.
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I've been writing asp.net apps with SQL Server back ends for the past 10 years. During that time, I have also written some PHP apps, but not many.
I'm going to be porting some of my asp.net apps to PHP and have run into a bit of an issue. In the Asp.net world, it's generally understood that when accessing any databases, using views or stored procedures is the preferred way of doing so.
I've been reading some PHP/MySQL books and I'm beginning to get the impression that utilizing stored procedures in MySQL is not advisable. I hesitate in using that word, advisable, but that's just the feeling I get.
So, the advice I'm looking for is basically, am I right or wrong? Do PHP developers use stored procedures at all? Or, is it something that is shunned?
Whether to use Stored Procedures or not is more of a religious or political discussion at a bar than not.
What needs to be done is clearly define your application layers and not step over those boundaries. Stored procedures have several advantages and disadvantages over doing queries outside of the database.
Advantage 1: Stored procedures are modular. This is a good thing from a maintenance standpoint. When query trouble arises in your application, you would likely agree that it is much easier to troubleshoot a stored procedure than an embedded query buried within many lines of GUI code.
Advantage 2: Stored procedures are tunable. By having procedures that handle the database work for your interface, you eliminate the need to modify the GUI source code to improve a query's performance. Changes can be made to the stored procedures--in terms of join methods, differing tables, etc.--that are transparent to the front-end interface.
Advantage 3: Stored procedures abstract or separate server-side functions from the client-side. It is much easier to code a GUI application to call a procedure than to build a query through the GUI code.
Advantage 4: Stored procedures are usually written by database developers/administrators. Persons holding these roles are usually more experienced in writing efficient queries and SQL statements. This frees the GUI application developers to utilize their skills on the functional and graphical presentation pieces of the application. If you have your people performing the tasks to which they are best suited, then you will ultimately produce a better overall application.
With all that in mind there are several disadvantages.
Disadvantage 1:
Applications that involve extensive business logic and processing could place an excessive load on the server if the logic was implemented entirely in stored procedures. Examples of this type of processing include data transfers, data traversals, data transformations and intensive computational operations. You should move this type of processing to business process or data access logic components, which are a more scalable resource than your database server.
Disadvantage 2:
Do not put all of your business logic into stored procedures. Maintenance and the agility of your application becomes an issue when you must modify business logic in Sp language. For example, ISV applications that support multiple RDBMS should not need to maintain separate stored procedures for each system.
Disadvantage 3:
Writing and maintaining stored procedures is most often a specialized skill set that not all developers possess. This situation may introduce bottlenecks in the project development schedule.
I have probably missed some advantages and disadvantages, feel free to comment.
Could also be because MySQL didn't get stored procedures until version 5. If you use prepared statement you should be okay...just don't use inline SQL
A couple of years ago I ended up writing a fair amount (~3K lines) of stored procedure code for a PHP/MySQL project. In my experience:
MySQL stored procedures probably aren't going to help you performance-wise.
Executing SPs through prepared statements with MySQLi can cause headaches.
It can be hard to abstract out common patterns—I found myself repeating myself more than I liked.
Depending on the MySQL version and configuration, you might need SUPER privileges to create SPs.
If you're porting code that uses stored procedures, it might be easiest to keep them. It's certainly possible to use them with PHP and MySQL, and I wouldn't personally call it inadvisable, exactly. I just probably wouldn't choose to use them again if I were starting a new PHP project from scratch.
In general, I very much dislike stored procedures because:
It's too easy to slip in business logic that shouldn't be there.
Updates to the application that require updates to your stored procedures is a pain to synchronize, especially if you have to revert to a previous build.
For any database manipulation, I recommend going with a PHP ORM framework like http://www.doctrine-project.org or a framework that includes ORM like CakePHP. You'll have an added bonus of being able to more easily switch between SQL Server and MySQL.
Stored procedures are -- often -- a complete waste of effort.
When in doubt, actually measure the performance. You'll often find that stored procedures add complexity for no recognizable benefit. You may have no performance enhancement from your SP's.
Some folks think they're very "Important". It's essential to actually measure performance rather than quibble or debate.
Many (most?) webapps use a database abstraction layer to take care of injection vulnerabilities/etc.
If you want one for your own app, take a look at PDO. Here is a big tutorial about how to use it:
http://www.devshed.com/c/a/PHP/Using-PDO-Objects-in-PHP-5/
What about SQL injection ?
Procedures allow you to do parameter invocation on the WHERE clause, reducing injection hazards
Here is a balanced and informed article on stored procedures in MySQL: http://www.linuxjournal.com/article/9652?page=0,0
To dismiss them out of hand as a "waste of time" or "hard to maintain" or "providing no real benefit" in any database and application of significant size would be very unwise.
I'm working on a PHP web application with PostgreSQL. All of the SQL queries are being called from the PHP code. I've seen no Views, Functions or Stored Procedures. From what I've learned, it's always better to use these database subroutines since they are stored in the database with the advantages:
Encapsulation
Abstraction
Access rights (limited to DB Admin) and responsibility
Avoid compilation
I think I read something about performance improvements too. I really don't see why the team hasn't used these yet. In this particular case, I would like to know, from experience, is there any good reason to NOT use them?
Mostly when there are so many "SELECT" queries along the code, why not use Views?
I am planning on refactoring the code and start coding the subroutines on the DB Server. I would like to know opinions in favor or against this. The project is rather big (many tables), and expects lots of data to be stored. The amount of data you would have in a social network with some more stuff in it, so yeah, pretty big.
In my opinion, views and stored procedures are usually just extra trouble with little benefit.
I have written and worked with a bunch of different web apps, though none with bazillions of users. The ones with stored procedures are awkward. The ones with ad-hoc SQL queries are plenty fast (use placeholders and other best practices to avoid SQL injection). My favorite use database abstraction (ORM) so your code deals with PHP classes and objects rather than directly with the database. I have increasingly been turning to the symfony framework for that.
Also: in general you should not optimize for performance prematurely. Optimize for good fast development now (no stored procedures). After it's working, benchmark your app, find the bottlenecks, and optimize them. You just waste time and make complexity when you try to optimize from the start.
I. Views offer encapsulation, but if not carefully designed they can slow down the application. Use with caution.
II. Use functions if needed, no reason to put them in if they are unneeded.
III. Stored Procedures are a godsend, use them everywhere there is a static query!!
In response to the views vs. queries, try to use views with Stored Procedure's, the Stored Procedure's will mitigate some of the performance hit taken with most views.
The advantage of stored procedures is that, because all the processing is done on the database, you do not incur network overhead shunting intermediate result sets back and forth.
The disadvantage is that each RDBMS system out there has its own peculiar syntax for stored procedures. By implementing your business logic in stored procedures, you're pretty much restricting your app to a single database product, something you need to keep in mind if you intend your application to be database independent. Also, as gahooa pointed out, because stored procedures live in the database, your access to them as a developer may be restricted by local policy; some organisations will only let DBAs touch the database.
#WolfmanDragon: I don't know if views inherently make things slower; your mileage may vary, I guess, depending on the complexity of the view and the RDBMS you're using. Plus, some RDBMS allow you to materialise commonly-used views so access to them is as fast as a base table.
We try to use the features you mentioned only where there is a significant benefit
Being part of the "Database", they fall under "schema changes", rather than "source code changes", and are naturally harder to version control.
Whatever you do, just make sure you retain full visibility of who-changed-what-when, so that you can diff, rollback, and recover in the case of problems.
I'm quoting part of an answer which I received for another question of mine:
In the PHP/MySQL world I would say
stored procedures are no-go
I would like to know: Is that so? Why? Why not?
[edit]I mean this as a general question without a specific need in mind[/edit]
I develop and maintain a large PHP/MySQL application. Here is my experience with stored procedures.
Over time our application has grown very complex. And with all the logic on the php side, some operations would query the database with over 100 short queries.
MySQL is so quick that the performance was still acceptable, but not great.
We made the decision in our latest version of the software to move some of the logic to stored procedures for complex operations.
We did achieve a significant performance gain due to the fact that we did not have to send data back and forth between PHP and MySQL.
I do agree with the other posters here that PL/SQL is not a modern language and is difficult to debug.
Bottom Line: Stored Procedures are a great tool for certain situations. But I would not recommend using them unless you have a good reason. For simple applications, stored procedures are not worth the hassle.
When using stored procedures with MySQL, you will often need to use the mysqli interface in PHP and not the regular mysql interface.
The reason for this is due to the fact that the stored procedures often will return more than 1 result set. If it does, the mysql API can not handle it and will you get errors.
The mysqli interface has functions to handling these multiple result sets, functions such as mysqli_more_results and mysqli_next_result.
Keep in mind that if you return any result set at all from the stored procedure, then you need to use these APIs, as the stored procedure generates 1 result set for the actual execution, and then 1 additional one for each result set intentionally returned from the stored procedure.
I generally stay away from stored procedures because it adds load to the database which is 99% of the time, your biggest bottleneck. Adding a new php server is nothing compared to making your MySQL db replicate.
Do you have a specific need in mind which makes you consider them? Stored procedures are much less portable than "plain" SQL, that's usually why people don't want to use them. Also, having written a fair share of PL/SQL, I must say that the procedural way of writing code adds complexity and it's just not very modern or testable. They might be handy in some special cases where you need to optimize, but I'd certainly think twice. Jeff has similar opinions.
This is a subjective question.
I would personally include all calculations within PHP and only really use MySQL as a table.
But, If you feel that it is easier to use stored procedures then by all means, go ahead and do it.
There's possibly a phobia of stored procedures with mysql, partly due to not being overwhelmingly powerful ( compared to Postgresql and even MSSQL, mysqls stored procedures are greatly lacking ).
On the plus: They make interfacing with it from more than one language easier.
If somebody states that "using stored procedures is bad because its not portable to different databases" then this of course means they think you're likely to switch databases, which means they in turn saying they think you shouldn't be using mysql.
It is popular to use ORM's these days, but I personally think ORM is a BadThing (Question:82882)
I would not say "stored procedures are a no-go", I would say "Don't use them without a good reason".
MySQL stored procedures have a particularly horrible syntax (Oracle and MSSQL are pretty awful too), maintaining them just complicates your application.
Do use a stored procedure if you have a real (measurable) reason to do so, otherwise don't. That's my opinion anyway.
I think that using stored procedures can offer some abstraction in certain applications, as in any where you would use the same SQL code chunk to update or add the same data, you could then create the one sproc save_user($attr.....) rather that repeating yourself all over the place.
Agreed the syntax is hairy and if your used to MSSQL and oracle sprocs there are differences that can fustrate.
You should also be aware that stored procedures were not supported in Mysql before version 5.0. http://dev.mysql.com/doc/refman/5.0/en/stored-routines.html Also stored procedures tended to be be a bit weird in that implementation. Now that Mysql 5.1 is starting to crop up in the wild I see more use of stored procedures with Mysql.
I make limited use of stored procedures, and it works well. I am the lead dev for one of my companies clients, working on their e-comm website. The client has a stock system, we implemented a set of stored procedures on their system and built an API to communicate with it. This allowed us to abstract their database and they could implement logic in the stored procedures. Simple but met the business requirement very well.