Implicit sort order on a database

[NotAllThere]

In my table of "which mod I hate the most" I have found the order is always changing.

Rubbish - that would imply there was a mod you hate least.

[GreenMirror]

In my table of "which mod I hate the most" I have found the order is always changing.

[woohoo]

Has anyone else found bugs in software caused by programmers assuming that a database table's data is stored in an implicit order?

Not for a while, perhaps 4 years ago.

[NickFitz]

Only my own

Back around 2000, a site I was working on suddenly started producing unexpected results because I'd left out an ORDER BY. It was using SQL Server, and apparently that had decided to rearrange its stuff on disk. The data in question, which had been coming back in order of insertion, started coming back in an entirely different order; as I recall, it started a couple of thousand records in, with the stuff at the "beginning" turning up much further down.

Luckily I knew that "different order to the one you expect" is usually, in fact, "unordered but giving the impression of having some kind of order as an artefact of the underlying implementation" so I was able to quickly diagnose and fix it. It would've been rather embarrassing had it made it into production

[NotAllThere]

Has anyone else found bugs in software caused by programmers assuming that a database table's data is stored in an implicit order?