kevin.kembel (1/2/2013)
I've look at Google and your links, and it still appears to me that what you said before isn't entirely correct - which is why I was hoping for some explicit clarification. The articles you just linked to are a perfect example of what I mean. They seem to contradict each other, as well as what you said about table variables and temp tables (quoted above). So far I'm still assuming that they do always write to disk - both temp tables and table variables because that's the bulk of what I've read as well as what I've experienced when I monitor my TempDB's MDF read/write usage. If RAM is available, they cache as per usual, but they will still always write to disk even if sufficient RAM is available.
I think that the source of confusion here is teh difference between allocating space for some data on the disc and actually writing the data to the disc.
Every page of table data, whether permanent table, temp table, or table variable, has to have space allocated for it on disc; however, it's possible that the data is never written to the space allocated for it. Most of the time, data is never written to the space allocated for table variables or for temp tables - that's what Gus is telling you; but all the time, space is allocated on disc so that the data could be written to disc if that became neccessary - that's what some of the references are telling you, but apparently it is so badly phrased as to appear to contradict what Gus told you.
Tom