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Displaying posts with tag: Stored Procedures (reset)
Next Week’s MySQL Sessions at ODTUG Kaleidoscope

By now you know that there is a MySQL Track during next week’s ODTUG Kaleidoscope in Washington, DC. Ronald Bradford and I organized the schedule at the last minute (Ronald did a lot of the work!). It was difficult to fill a schedule with 19 sessions that are either 1 hour or 1.5 hours long, and to do it I ended up with three presentations.

At each presentation I will be giving away a copy of The MySQL Administrator’s Bible, so be sure to show up! All MySQL track sessions are in Maryland C, and all times are Eastern.

On Monday, June 28th from 4 pm – 5:30 pm I will be presenting …

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Getting started with MySQL 5.5



Some time go, we announced a new release model for MySQL. As all new things, it had some initial hiccups (with MySQL 5.4 we were still getting acquainted with the new model), but now it seems to be in full swing.
By the time you read these lines, MySQL 5.5 will be available. If the mirrors aren't seeded yet, the impatient can compile and use the new version from the launchpad source tree..

OverviewWhat's this new …

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New white paper: Guide to Optimizing Performance of the MySQL Cluster Database

MySQL Cluster Connection Pooling

This guide explores how to tune and optimize the MySQL Cluster database to handle diverse workload requirements. It discusses data access patterns and how to build distribution awareness into applications, before exploring schema and query optimization, tuning of parameters and how to get the best out of the latest innovations in hardware design.

The Guide concludes with recent performance benchmarks conducted with the MySQL Cluster database, an overview of how MySQL Cluster can be integrated with other MySQL storage engines, before summarizing additional resources that will enable you to optimize MySQL Cluster performance with your applications.

Download the white paper (as always, for free) from: …

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A micro-benchmark of stored routines in MySQL

Ever wondered how fast stored routines are in MySQL? I just ran a quick micro-benchmark to compare the speed of a stored function against a "roughly equivalent" subquery. The idea -- and there may be shortcomings that are poisoning the results here, your comments welcome -- is to see how fast the SQL procedure code is at doing basically the same thing the subquery code does natively (so to speak).

Before we go further, I want to make sure you know that the queries I'm writing here are deliberately mis-optimized to force a bad execution plan. You should never use IN() subqueries the way I do, at least not in MySQL 5.1 and earlier.

I loaded the World sample database and cooked up this query:

PLAIN TEXT SQL:

  1. SELECT sql_no_cache sum(ci.Population) FROM City AS ci
  2.   WHERE …
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Creating a MySQL plugin to produce an integer timestamp

This article shows how to create a MySQL-plugin that can be used to create a function which can in turn be used in stored procedures. The function will produce an integer value representing the time (to the nearest usec).

I’m working on an article for conflict detection/resolution when using MySQL Cluster asynchronous replication which requires an integer column to store a timestamp for comparison purposes. In fact, it doesn’t actually need the timestamp to represent an absolute or even a relative point in time – all it cares about is that the if the function is called twice on 2 different hosts that the 2nd call will always result in a larger number than the 1st. Obviously, in a production environment the times on the 2 hosts would need to be kept in sync.

The c code (inttime.c)

#include <mysql.h>
#include <sys/time.h>

my_bool inttime_init(UDF_INIT *initid,UDF_ARGS *args, char *message) {
  return 0;
} …
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MySQLi result set iteration - recursive

PHP 5.3 is released and after the release stress is over my mind is open for new ideas. While relaxing yesterday I thought about many things, among them was the Resultset iterator I recently discussed.

Now I wondered where to go next with this and had the idea that an individual Resultset is a child of the whole result and this might be wrapped in an Recursive Iterator. For doing so we don't implement the Iterator interface but RecursiveIterator. RecursiveIterator extends a typical Iterator with two methods: hasChildren() and getChildren(). But now we have a problem: The Iterator returned by getChildren() has to be a RecursiveIterator, too, which makes sense, in general. But I want to return a MySQLi Resultset which isn't recursive - so making this a RecursiveIterator is wrong. My solution now is to introduce yet another Iterator which goes by …

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MySQLi Resultset Iterator

Over at phpdeveloper.org I was pointed to a blog post talking about MySQLi and stored procedures. That reminded me about a small thing I recently did: When using MySQLi's multi_query to send queries which return multiple result sets you have to use a rather unintuitive API which can certainly be improved.

Recently I sat down and cooked up a small improvement for that, being an iterator fan I, of course, had to use an iterator for that and implemented the following class:

<?php
class MySQLi_ResultsetIterator implements Iterator {
    private $mysqli;
    private $counter = 0;
    private $current = null;
    private $rewinded = false;

    public function __construct(mysqli $mysqli) {
        $this->mysqli = $mysqli;
    }
    private function freeCurrent() {
        if …
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Are Stored Procedures available with MySQL Cluster?

The answer is yes – kind of.

Stored procedures are implemented in a MySQL Server and can be used regardless of the storage engine being used for a specific table. One inference from this is that they won’t work when accessing the Cluster database directly through the NDB API.

This leads to the question of whether or not that limitation actually restricts what you can achieve. This article gives a brief introduction to stored procedures and looks at how the same results can be achieved using the NDB API.

Stored procedures provide a rudimentary way of implementing functionality within the database (rather than in the application code). They are implemented by the database designer and have the ability to perform computations as well as make changes to the data in the database. A typical use of stored procedures would be to control all access to the data by a user or application – for example, to impose extra checks on …

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Stored Procedures Are Slow Part 2

Last time I demonstrated a case where stored procedures are slow.  There were a few comments that I should include selects in the stored procedure to make the tests  more realistic.  From experience I already knew the answer so I didn’t go into that level of detail, but since stored procedures are all about database access this is a reasonable comment. 

This is a simple stored procedure that selects data and then summarizes it by customer.  No one would actually write this as it is far too easy to use a SQL statement instead.    Assume the logic is more complex and can’t be done easily by the standard SQL techniques of case statements, temp tables, etc, and then this makes more sense.  

The end result is this stored procedure takes 696 seconds to run. 

 

create procedure slowCounter()
begin

    declare done int …

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Are MySQL stored procedures slow?

 

Yes, if compared to code in Java or C#. For example, this overly simple code took 284 seconds.

CREATE PROCEDURE CountTest()
begin
    declare counter int default 0;
    select now();
    repeat
        set counter = counter + 1;
    until counter > 120000000
    end repeat;
    select counter;
    select now();
end

Ignoring my off by one error, here is equivalent code in C# (the language I’m currently learning).  It took 419 milliseconds, or MySQL took 677 times longer to execute. From my experience, Java isn’t going to be any slower.

 int counter = 0;
while (counter < 120000000)
{
    counter++;
}

Slow stored procedure …

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