Month: July 2008
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Linux CentOS – Kernel panic
This looks like an error with memory by sim. Anyone has a better clue? The kernel version is 2.6.9-67.0.4.EL, then we rebooted and upgraded to 2.6.9-67.0.20.EL. Any kernel bug I should be aware of? Jul 13 04:03:13 host syslogd 1.4.1: restart. Jul 16 08:00:01 host kernel: swap_free: Unused swap offset entry 00010000 Jul 16 08:00:01…
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jQuery, Google AJAX APIs
We recently implemented jQuery into our ad server, majorly for future feature expansions and hopefully convert some of the existing JS enhancements using jQuery for a simpler codebase. Google AJAX API is nice but does not support SSL, which is quite inconvenient.
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Frustrations with Google AdWords
Google withholds lots of data for their own data-mining purposes. The stated level of click frauds is definitely questionable from our own experience. Don’t forget to check your own click logs and adjust your account promptly or Google and their affiliates are wasting your budget. Their customer service representative often replies with a very long…
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MySQL – SHOW commands are expensive
It’s convenient to display information about a table, running status, server configurations. However, it is expensive! A simple “SHOW COLUMNS FROM SomeTable” create a disk-based temporary table!!! The same for “SHOW STATUS LIKE ‘Created_%’”. Lesson: avoid these if you don’t want to see “Created_tmp_disk_tables” and “Created_tmp_tables” counters spinning. It’s not a bug but can mislead…
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Issue with MySQL replication
For some reasons I have not been able to pin point exactly which piece goes wrong, if a master has too many slaves, it will have quite a few issues. 1) lighttpd regularly get backend overloaded errors; 2) ping to this server will fluctuate drastically. And I don’t think it’s that many slaves.
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Windows Vista Firewall
If I didn’t know, I would say it sucks and install another firewall, like ZoneAlarm for all my other XP computers. However, after an issue with delay and slow connection to localhost, I have identified the problem is with conflicting firewalls. Uninstalled ZoneAlarm, then tweak Vista Firewall, it’s quite powerful (use w/ Advanced Security option).…
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SHOW TABLE STATUS FROM MyDatabaseName;
Run that query if you would like to know basic details about a database, especially the overhead to see if you would need to optimize it. Name: AdSpeedDB Engine: MyISAM Version: 10 Row_format: Dynamic Rows: 0 Avg_row_length: 0 Data_length: 4676 Max_data_length: 281474976710655 Index_length: 3072 Data_free: 4676 Auto_increment: 221 Create_time: 2007-08-01 17:15:24 Update_time: 2008-06-03 07:26:13 Check_time:…