Why do my emacs comint buffers sometimes seem to share the same history?

I often have several comint buffers open at once, for example I'll have a SQLi buffer open to a database and a set of shell buffers open in various places. Sometimes, for no reason I can detect, all of these buffers start to share a common buffer command history, such that M-p will pull up my last SQL command in a shell-mode buffer, and so on.

H开发者_运维知识库ow can I fix this? What on earth is causing it?

Have you exited from any of the shells or SQL sessions? Long time since I used emacs but I seem to remember when a shell terminated the commands would be part of a 'global-command-history-list'.

note - A shell can quit, but the buffer will still be there in emacs.

It sounds like there is something else going on in your system that you are not aware of. One possibility may be something in your .emacs is mixing between buffers without your knowledge. Another possibility is that you are inadvertently moving data through your copy-and-paste system.