database

If you find that you Drupal installation is WSOD-dead with the following error message:
Error: Class 'SelectQueryExtender' not found in includes/pager.inc

then this means that you've messed up the Drupal (7, at the time of writing) registry somehow. You might have done this during an import/export operation where you forgot to export the registry and registry_file tables, or as I did, you have foolishly just emptied them to clear up issues with a missing class file that Drupal fastidiously continues to track.

While trying to import a CSV file into MySQL today using the LOAD DATA INFILE command, I ran into the following situation:

mysql> LOAD DATA INFILE 'foo.csv' INTO TABLE bar FIELDS TERMINATED BY ',' ENCLOSED BY '#' LINES TERMINATED BY '\r' (a, b);
ERROR 29 (HY000): File 'foo.csv' not found (Errcode: 13)

The file exists fine and the permissions are also kosher. After much gnashing of teeth and perusing of documentation, I found out that local file sources require the LOCAL keyword:

I installed MySQL on my local server today and when I went to access it via mysql_secure_installation to set my root password etc., I ran into the following curious error:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

While I initially thought that it was some kind of installation issue, after much scratching of pate, I realised that Occam was right and that I should be checking the simpler things first. Sure enough, after a quick check, I found that MySQL was not even running :/