Planet MySQL Planet MySQL: Meta Deutsch Español Français Italiano 日本語 Русский Português 中文
Showing entries 1 to 10 of 20 10 Older Entries

Displaying posts with tag: c (reset)

C Library Visibility
+0 Vote Up -0Vote Down

I was surprised by the recent announcement that MySQL are going to start to conceal the hidden function calls in their C connector. Surprised because although this is great news I had expected them to do this years ago. Working for HP's Advanced Technology Group I realise I take such things for granted. For this blog post I'm going to talk about why it is important and how to do it.

So, when you create a dynamic library in C the default thing that happens is every function call in that library effectively becomes a potential API call. Whether …

  [Read more...]
Popular Programming Languages
+0 Vote Up -0Vote Down

First of all, Happy New Year!

IEEE Spectrum published a ranking of the most popular programming languages. Computational journalist Nick Diakopoulos wrote the article. While it may surprise some, I wasn’t surprised to find SQL in the top ten.

Nick weighted and combined 12 metrics from 10 sources (including IEEE Xplore, Google, and GitHub) to rank the most popular programming languages.

  • Compiled …
  [Read more...]
Why Stored Programs?
+0 Vote Up -0Vote Down

Why should you use stored programs? Great question, here’s my little insight into a situation that I heard about in a large organization.

A very large organization is having a technology argument. In someway, like politics, half-truth drives this type of discussion. This company has hundreds of databases and they’re about half SQL Server and Oracle. The argument (half-truth) states that using T-SQL or PL/SQL yields “spaghetti” code!

It seems like an old argument from my perspective. After all, I’ve been working with T-SQL and PL/SQL for a long time. Spaghetti code exists in every language when unskilled programmers solve problems but …

  [Read more...]
Separate docs for MySQL Connectors
+1 Vote Up -0Vote Down

The MySQL documentation section has always had this Topic Guides page containing links to the docs for the various MySQL Connectors -- the official database drivers for various languages and programming technologies. That is the most convenient way to get the information for each Connector in PDF form, rather than downloading the entire Ref Man PDF. For HTML, it was more of a shortcut, because

MySQL LDAP Authentication Plugin (Clear password client plugin)
+1 Vote Up -0Vote Down

Based on my last post MySQL LDAP Authentication Plugin, I received feedback from MySql Joro Blog by Oracle.

They told me:

Insted of writing (and having to deply) your own client plugin you probably can reuse the cleartext client side plugin, specially because it’s available in a number of mysql clients already. Check sql-common/client.c on MySQL 5.5+ for details.

This is very useful because you only need to put the plugin in server side, and …

  [Read more...]
MySQL LDAP Authentication Plugin
+3 Vote Up -0Vote Down

As a continuation of previous post, now, I will show how to make a mysql plugin for ldap authentication.

Get the mysql-server source code at http://dev.mysql.com/downloads/mysql/ (http://dev.mysql.com/get/Downloads/MySQL-5.5/mysql-5.5.27.tar.gz/from/http://cdn.mysql.com/)

Installing necessary packages

yum groupinstall 'Development Tools'
yum install cmake ncurses-devel

Download source code, build and start MySQL Server

wget http://dev.mysql.com/get/Downloads/MySQL-5.5/mysql-5.5.27.tar.gz/from/http://cdn.mysql.com/
tar -xzf mysql-5.5.27.tar.gz
cd mysql-5.5.25

# Preconfiguration setup …
  [Read more...]
LDAP C Client Authentication Example (with OpenLDAP)
+0 Vote Up -0Vote Down

I have the goal of authenticate MySQL users with an LDAP server, currently, employees of my company are authenticated in several services (ftp, ssh, svn) through my LDAP server, except MySQL. (As you can imagine, I need to add manually every user in MySQL, a very tedious task).

In this post I only leave the example with LDAP authentication.

Installing necessary packages


yum groupinstall 'Development Tools'
yum install openldap-devel

Source ldapClient.c

#include <stdio.h>
#include <ldap.h>
/* LDAP Server settings */
#define LDAP_SERVER …
  [Read more...]
Integer overflow
+0 Vote Up -1Vote Down

What do you think of this piece of C code?

  void foo(long v) {
    unsigned long u;
    unsigned sign;
    if (v < 0) {
      u = -v;
      sign = 1;
    } else {
      u = v;
      sign = 0;
    }
    ...

Seems pretty simple, right? Then what do you think of this output from MySQL:

  mysql> create table t1 (a bigint) as select '-9223372036854775807.5' as a;
  mysql> select * from t1;
  +----------------------+
  | a                    |
  +----------------------+
  | -'..--).0-*(+,))+(0( | 
  +----------------------+

Yes, that is authentic output from older versions of MySQL. Not just the wrong number, the output is complete garbage! This …

  [Read more...]
Dennis Ritchie, the creator of C, dies at 70..
+2 Vote Up -0Vote Down

When I first got in touch with C it was in the early 1980's. I was a sysadmin at a Swedish telco operator (then THE Swedish Telco operator, Televerket, nowadays called Telia) for a system used for software development for a PABX system called A345 in Sweden, better known as Meridian in the rest of the world (co-developed by Televrket and Nortel). The Meridian system was the biggest of the non-custom built PABXes in those days. The language used to program it was called SL-1 (Switching Language 1) and the development system, like editors (vi / ined), compilers etc was running on a Unix system.

This sure was one of the …

  [Read more...]
New algorithm for calculating 95 percentile
+1 Vote Up -0Vote Down

The 95 percentile for query response times is and old concept; Peter and Roland blogged about it in 2008. Since then, MySQL tools have calculated the 95 percentile by collecting all values, either exactly or approximately, and returning all_values[int(number_of_values * 0.95)] (that’s an extreme simplification). But recently I asked myself*: must we save …

  [Read more...]
Showing entries 1 to 10 of 20 10 Older Entries

Planet MySQL © 1995, 2015, Oracle Corporation and/or its affiliates   Legal Policies | Your Privacy Rights | Terms of Use

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.