SEMrush keeps taking down my site

My site is being absolutely bombarded by page requests originating from semrush.com. Its a bot that is¬†indexing and downloading links to my entire site, which would be fine if it were a small website, except that I have content going back to 1996, which is rather a lot, and they are hitting the server with …
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MySQL Collation Error

Occasionally I come across databases written by other developers who have a complete mix of character sets, and where the database character set does not match the character set of fields within a table. This causes all sorts of nasty errors when trying to use CONCAT or CONCAT_WS. Errors like: Illegal mix of collations for …
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MySQL ibtmp1 file grows exponentially

Recently we have had several servers run out of hard drive space causing inaccessibility and crashing. On further investigation the hard drive was full so many operations were complaining. The hard drive was being consumed by a very large file within the /var/lib/mysql directory called ibtmp1. ibtmp1 is a temporary working file for MySQL. When …
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