KnowledgeTree notes

Failed to retrieve documents: DB Error: unknown error

If KnowledgeTree just outputs the error message Failed to retrieve documents: DB Error: unknown error, check the log files in ${KNOWLEDGETREE_ROOT}/var/log. The newest file will show you the function that it just tried to execute and. Just copy and paste it to the MySQL prompt.

In my case, when trying to executing the query from the MySQL prompt, I got the following error:

ERROR 1030 (HY000): Got error 28 from storage engine

I then saw, in this message on the MySQL forum, that it could be that a partition that filled up.

Also, the perror MySQL utility told me about the error 28 I got on that error message:

$ perror 28
OS error code  28:  No space left on device

df -h told me that /tmp was full, so I just deleted some stuff that was there, but was not necessary, and everything was OK. I didn't know MySQL used /tmp, but it is not a good idea to let it full, although it doesn't need to be big (mine was too small: about 1MB - by probably an error during the install process -, but MySQL and other services worked very well with it).