There is an old joke about an engineer, a mathematician, and a philosopher sitting together in a train travelling from London (England) to Cardiff (Wales) ***
As the train crosses the border, the engineer glances out of the window and exclaims: “Oh, look! Welsh sheep are black”.
The mathematician responds: “No; all you can say is that there is at least one sheep in Wales that is black.”
The philosopher corrects both of them: “Gentlemen, all you can claim is that there appears to be a sheep in Wales that seems to be black on one side.”
(Trust me, in 1970, this was quite funny).
The point of telling the tale is this: the best viewpoint to take when trouble-shooting an Oracle database is that of the mathematician – don’t, as the engineer did, leap to extreme conclusions based on just one observation , but don’t, as the philosopher did, get so stuck into such tiny details of theoretical correctness that reasonable assumptions are swept aside.
*** Footnote: for those not familiar with the geography of the UK: “The UK” is “The United Kingdom of Great Britain and Northern Ireland” and “Great Britain” is the union of England, Scotland (most of the top half of the island), and Wales (the lump at the left hand side, excluding the thin pointy bit at the bottom).