in reply to Re^2: Recoding a multi-sql-statement storedProc transaction in a script
in thread Recoding a multi-sql-statement storedProc transaction in a script

Stored procedures have a number of disadvantages compared to SQL embedded in a perl script.

I know next to nothing about SQL Server, but as an Oracle guy, I have to speak up in support of stored procedures.

One big one is that you need DBA privileges to manage them.

If that is really the case, it is an SQL Server oddity. Oracle lets everyone create and manage his own stored procedures.

Another is that updating them and backing them up is typically more complex than the basic source control steps used for perl code.

When you back up your database, that backup includes stored procedures. You can update them very easily using the DB SQL client. Of course, you want to put them into source control. You can use the same source control system you use for your Perl code.

The biggest one for me is that things which are not pure SQL -- i.e. procedural stuff in the programming language supported by the database -- is usually done in some crippled language without modern constructs or solid debugging tools like Perl's.

Well, those languages are domain languages, and are mainly intended to query the database, which they can do much more elegantly than more general languages (including Perl). Also, some DBMS have plugins that let you write stored procedures in Perl (not sure if that is a good idea, though).

There is a performance advantage to them when they involve examining a large number of rows that are not actually needed in the end result, but this is not that common a situation.

There are also the performance advantages of not having to parse and prepare the SQL every time (that will be done only once, and not just once per connection, which is the best you can do from the outside), of using native database datatypes, and of reduced network traffic.

And then we have: easier transaction management in Perl (just keep AutoCommit on, one transaction can always be a single statement), shorter, simpler code (Perl just needs to call stored procedures, which is simple with our excellent DBI, the stored procedures themselves are usually more concise than their Perl counterparts), accessibilty of the code from other programming environments, the ability to fix code and to see dependencies in one place (rather than everywhere on your server farm) and data validation right in the database.

Forgive the rant, but I am a hopeless PL/SQL fan boy, and try to keep my programs completely free of any SQL (for the same reasons that I keep them free of HTML). It is all about separation of concerns and using the right tool for the job.

  • Comment on No stored procedure bashing on my watch!

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Re: No stored procedure bashing on my watch!
by perrin (Chancellor) on Dec 15, 2004 at 20:10 UTC
    I know next to nothing about SQL Server

    I've never used SQL Server. My comments refer to Oracle.

    Oracle lets everyone create and manage his own stored procedures.

    Only if you have DBAs who are happy to grant that privilege. None of the ones I've worked with were.

    When you back up your database, that backup includes stored procedures. You can update them very easily using the DB SQL client. Of course, you want to put them into source control. You can use the same source control system you use for your Perl code.

    No special procedure is required to make perl code live in a typical environment. For stored procs, you have to connect to the database and install the new version. It's not horrible, but it is more work than file-based stuff. And it adds to versioning problems between code and database. A good automated code deploy tool could probably fix this issue, but most places don't have one.

    There are also the performance advantages of not having to parse and prepare the SQL every time (that will be done only once, and not just once per connection, which is the best you can do from the outside), of using native database datatypes, and of reduced network traffic.

    With Oracle, when you use placeholders correctly, statements are parsed and then kept in the cache. Sending the request again doesn't require it be parsed again. The network stuff is a savings if you need to examine lots of rows but won't actually be needing them in your final results, as I mentioned. Otherwise, it's negligible.

    accessibilty of the code from other programming environments

    That's the big argument in favor of stored procs, and the only one that I actually buy. I don't think PL/SQL is an adequate language for this kind of development though.

    Forgive the rant

    Ditto! We disagree about most of this, but some of that is surely due to different database policies at our places of work.

    try to keep my programs completely free of any SQL (for the same reasons that I keep them free of HTML)

    There are some nice modules for keeping your SQL statements in a separate file. That's a nice way to do it for people like me who want to avoid stored procs.

[reply]
      As a former DBA, not wanting to use stored procedures sounds to me as someone coming perlmonks asking how to do "X", without using modules. And the reason "my DBA doesn't give me permission" is similar as "I don't want to use Perl modules because the sysadmin doesn't let me install any".

      I'm a great fan of stored procedures, and IMO, no application should ever touch a table directly. Not even with a select. Stored procedures should act as an extra abstraction level. Besides from the reasons given by other people, it gives database people the opportunity to re-organize the data layout (add/delete columns, split tables) without having to modify an unknown number of programs - all that's needed is to change the relevant stored procedures. Granted, probably less important for a database that's the backend for a short-lived website, but very important for databases that will last for decades, with a myriad of applications running against it. If there's any intention your database is going to last for a while, in an environment that might change don't use any SQL code in your applications (except for calling stored procedures). Ever.

      If your DBA doesn't give you permission, you have a problem. But not a problem different than your sysadmin not giving you permission to write files either. Would you accept the latter, and search for a way to get programs on the system (perhaps by typing them in on the command line each time you want to run them)? Or would you make it so that you get access? Assuming your application is important for someone, go and get the access you need! Talk to your manager.

[reply]
        don't use any SQL code in your applications (except for calling stored procedures). Ever.

        Shameless plug: DBIx::ProcedureCall makes Perl wrappers for stored procedures, eliminating the SQL to call them from your application source code as well. Only works for Oracle at the moment, though (contributions for other DBMS always welcome).

[reply]
        I don't buy it. Change the data structures around in a significant way and hide it all with stored procs? You'd end up with something messy and slow, just like all of those awful "we'll fix it with a view" solutions.

        Many DBAs are reluctant to give out permission for developers to modify stored procs. They see it as a way to make sure that all SQL is filtered through them. The problem is, they tend not to have any time to look at your SQL either, so the vetting process becomes a bottleneck.

        That sort of thing can be fixed, albeit slowly and painfully, but it doesn't change the fact that stored procs normally use crippled languages. I wouldn't want to use them for anything with actual programming logic in it.

[reply]
        ...don't use any SQL code in your applications (except for calling stored procedures). Ever.

        Abso-bloody-lutely!

        Examine what is said, not who speaks.        The end of an era!
        "But you should never overestimate the ingenuity of the sceptics to come up with a counter-argument." -Myles Allen
        "Think for yourself!" - Abigail        "Time is a poor substitute for thought"--theorbtwo         "Efficiency is intelligent laziness." -David Dunham
        "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon
[reply]
        I feel like poor Paco.

        I fully understand the value of storedProcs, and the value of abstracting, and the value of not using SQLs in the scripts, etc. I merely wanted to find out how to replicate a multi-command SQL proc in my script, because, well..., because I wanted to.

        I have come to the conclusion that it is messy to do so because DBI doesn't seem to provide the ability of abstracting the transactions for me, but that is a good and valuable conclusion.

        Now, I have a minor quibble to pick with the above post.

        Besides from the reasons given by other people, it gives database people the opportunity to re-organize the data layout (add/delete columns, split tables) without having to modify an unknown number of programs - all that's needed is to change the relevant stored procedures.

        Well, what the heck are storeprocs other than an "unknown number of programs?" I can't see how the db structure can be changed, and yet storedProcs can prevent any pain? Whether I get to the data via a SQL statement in my Perl script, or via a storedProc in the database called from my Perl script, somewhere, someone will have to change something.

        I think the dba types tend to think one way only -- that the world depends on the database they are custodians of. While that may be true in their realm, there are tons of small programs and processes that are run using databases where the dba can't do everything. The programmer has to find ways to do things in a variety of ways.

        That is the kind of situation I ran into.

        Anyway, thanks everyone for the input. Every bit helps.

[reply]

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