I recently had a long conversation with Joe Stump, CTO of SimpleGeo, about location, geodata, and the NoSQL movement. Stump, who was formerly lead architect at Digg, had a lot to say. Highlights are posted below. You can find a transcript of the full interview here.

Competition in the geodata industry:

I personally haven't seen anybody that has come out and said, "We're actively indexing millions of points of data. We're also offering storage and we're giving tools to leverage that. I've seen a lot of fragmentation." Where SimpleGeo fits is, I really think, at the crossroads or the nexus of a lot of people that are trying to figure out this space. So …

Introduction

If your WordPress comment counts got messed up, whether because of a plugin (I'm talking about you, DISQUS) or you messed with your database manually and did something wrong (yup, that's what I just did), fear not – I have a solution for you.

But first, a little background.

Comment Counts In WordPress

Here's how comment counts work in WP:

• Posts live in a table called wp_posts and each has an ID.
• Comments reside in a table called wp_comments, each referring to an ID in wp_posts.
• However, to make queries faster, the comment count is also cached in the wp_posts table, rather than getting calculated on every page load.
  If this count ever gets out of sync with the actual number of comments for some reason, WordPress, while still displaying all comments properly, will simply show the wrong count. …

We have an early draft of a new tool available for you to use and test. It uses heuristics to find problems in SQL. Please use it and give feedback! Here’s how:

$ wget http://www.maatkit.org/trunk/mk-query-advisor
$ perl mk-query-advisor /var/log/mysql/slow.log

By default it consumes a log file in MySQL’s slow query log format, but it can also parse the general-log format, and if you have any other kind of log you can feed it through mk-query-digest to transform the log into something it can recognize. Tell me if you’d be able to spot the mixture of join styles and use of leading % wildcards in the following query without help:

# Query ID 0x643E813A9ABDA151 at byte 2001701
# CRIT JOI.001 Mixing comma and ANSI joins.
# WARN ARG.001 Argument with leading wildcard.
SELECT `rhubarb_series_title`.`id`, `rhubarb_series_title`.`series_id`, …

I am rather excited about being able to do awesome things such as this to get the current configuration of your server:

drizzle> SELECT NAME,VALUE
    -> FROM DATA_DICTIONARY.INNODB_CONFIGURATION
    ->  WHERE NAME IN ("data_file_path", "data_home_dir");
+----------------+-------+
| NAME           | VALUE |
+----------------+-------+
| data_file_path | NULL  |
| data_home_dir  | ./    |
+----------------+-------+
2 rows in set (0 sec)

drizzle> SELECT NAME,VALUE
    -> FROM DATA_DICTIONARY.INNODB_CONFIGURATION
    -> WHERE NAME IN ("data_file_path", "data_home_dir");
+----------------+-------+
| NAME           | VALUE |
+----------------+-------+
| data_file_path | NULL  |
| data_home_dir  | ./    |
+----------------+-------+
2 rows in set (0 sec)

drizzle> SELECT NAME,VALUE
    -> FROM DATA_DICTIONARY.INNODB_CONFIGURATION
    -> WHERE NAME = "io_capacity";
+-------------+-------+
| NAME        | VALUE | …

Persistence Smoothie: Blending NoSQL and SQL – see user feedback and comments at http://joind.in/talk/view/1332.

Michael Bleigh from Intridea, high-end Ruby and Ruby on Rails consultants, build apps from start to finish, making it scalable. He’s written a lot of stuff, available at http://github.com/intridea. @mbleigh on twitter

NoSQL is a new way to think about persistence. Most NoSQL systems are not ACID compliant (Atomicity, Consistency, Isolation, Durability).

Generally, most NoSQL systems have:

• Denormalization
  
• Eventual Consistency
  
• Schema-Free
  
• Horizontal Scale
  

NoSQL tries to scale (more) simply, it is starting to go mainstream – NY …

I’ve submitted a Birds of a Feather session for Maatkit at the upcoming MySQL conference. It’s not on the public schedule yet, but it has been accepted and scheduled for 19:00 on 13 Apr 2010. See you there!

Related posts:

1. Presentation uploaded for Maatkit talk at MySQL Conference The slides
2. I’ll be speaking at the O’Reilly MySQL Conference 2010 I’m
3. Learn about Maatkit at the MySQL Conference …

It seems that a lot of people equate non-SQL databases with non-relational-ness, or malign the word relational. This is pretty much pure ignorance. If you’ve ever uttered a sentence that includes the phrase “…non-relational database…” then I have two suggestions for you.

1. Study relational algebra. At a bare minimum, read the Wikipedia article on relational algebra. There is much more you could do — take a class on the topic, or read C.J. Date’s SQL and Relational Theory (my review). Ask yourself how similar SQL is to the relational algebra. How is relational algebra different …

I’ve been noticing an undeniable trend in my consulting engagements in the last year or so, and when I vocalized this today, heads nodded all around me. Everyone sees a growth in the number of cases where otherwise well-optimized systems are artificially limited by InnoDB contention problems.

A year ago, I simply wasn’t seeing the need for analysis of GDB backtraces en masse. These days, I’m writing custom tools to gather and analyze backtraces. A year ago, I simply looked at the SEMAPHORE section of SHOW INNODB STATUS. These days I’m writing custom tools to aggregate and reformat that data so I can interpret it more easily. And I’m actually seeing cases of this type of problem multiple times every week. I remember the first time I ran into a server that was literally optimized to the limit, but struggling under the load. It was something new for me, not that long ago. Oh, I’d seen it before, plenty, but was always able to point …

One of my colleagues, Ryan Lowe, has just heard that his session on PCI compliance with MySQL has been accepted at the upcoming MySQL conference. Ryan is highly qualified to present this topic, and not many people can say that; I certainly can’t claim that title myself. If you’re looking to learn how to make your MySQL installation PCI-compliant, there’s also not a lot of trustworthy information online. Personally — and really, no bias just because he’s my colleague — I think this is a great session for the MySQL conference, which I sometimes thought didn’t have enough diversity of topics in past years. We need more stuff like this to give people a reason to return after they’ve gone for 2 or 3 years in a …

I’ll be helping Morgan Tocker deliver the second half of his training course for MySQL Developers/DBAs in New York City in a few days (more Percona training). It was a snap decision at the last minute, but I’m hoping I’ll still get to meet some folks there. If we’ve corresponded over email or blog comments and you would like to get together, ping me in the comments here!

If you’re in the New York City area and you use MySQL, you should consider attending this course, too. Morgan knows his stuff and has written a good curriculum. Attendees give his courses excellent feedback, and the price is very reasonable. Oh, and I’ll be there too, did I mention that? You can pick my …