'Data' Tag

• What is this MySQL file used for?

  February 16, 2011

  MySQL keeps many different files, some contain real data, some contain meta data. Witch ones are important? Witch can your throw away? This is my attempt to create a quick reference of all the files used by MySQL, whats in them, what can you do if they are missing, what can you do with them. [...]

  posted in Tips & Tricks by mark

• HandlerSocket plugin – NoSQL/SQL interactions

  December 28, 2010

  HandlerSocket is cool. But, it turns out there are a few issues. Justin Swanhart points out HandlerSocket currently lacks atomic operations . Since HandlerSocket uses different connections for reading and writing, you can’t increment/decrement a value without creating a race condition. Still, the idea of skipping SQL interpretation and just reading the data you know [...]

  posted in Code, Commentary by mark

• MySQL GIS – Part 4

  September 21, 2010

  WHAT CAN YOU DO WITH GEO DATA? Geo spatial indexes are what make this type of data valuable.  With shape and point data you can find relationships between object in our physical world.  How close is the lightning in the storm front?  What homes where hailed on? (WDT) What schools are in my city?  With a [...]

  posted in GIS by mark

• MySQL GIS – Part 3

  September 7, 2010

  What data is available? GEO data is expensive to create, so has been created by governments.  In the past governments charged for this data.  In 1980 the USGS was charging $300 (usd) per county for Oklahoma GEO data. (I complained to my congressman.) Today, a quick Internet search turns up lots of free GIS data. I was [...]

  posted in GIS by mark

• MySQL GIS – Part 1

  August 23, 2010

  In my business (weather) we use lots map based (Geo) information.  Almost every table has latitude and longitude. Working with this kind of data can be exciting and frustrating.  This should give you a quick start into GIS with MySQL. “A geographic information system (GIS), or geographical information system, is any system that captures, stores, [...]

  posted in GIS, HOW TO, Tips & Tricks by mark

• Does Size or Type Matter?

  July 27, 2010

  MySQL seems to be happy to convert types for you. Developers are rushed to complete their project and if the function works they just move on. But what is the costs of mixing your types? Does it matter if your are running across a million rows or more? Lets find out. Here is what the [...]

  posted in Tips & Tricks, Tunning by mark

• Federated Tables

  July 7, 2010

  Your searching for how to create a join across two databases on two different servers and it can’t be done directly.   select  d1.a, d2.b from db1@server1 join db2@server2 where db1.c = db2.c; does not work. You learn about federated databases.  The federated storage engine allows accesses data in tables of remote databases.  Now how do [...]

  posted in Tips & Tricks by mark

• mg_hot_replace_table.pl

  May 1, 2010

  Do you have MyISAM tables you reload with new data? Do your queries, using that table, get blocked because the table is locked? Do the waiting queries create idle connections slowing down the table load? Do you wish you could just replace the table? Years ago I was told you can replace CSV tables by [...]

  posted in Code by admin

• Loading Bulk CSV Tables

  March 23, 2010

  In my job I use many data tables that are transient.  New weather data is received all the time and old data is purged.  Most of these table are received as CSV files.  The data is then loaded into MySQL tables and indexed to be used with geographic queries. Most of these tables never see [...]

  posted in Tips & Tricks by mark