In may, I started a thread on the consistency guarantees afforded by
READ COMMITTED. I was wondering whether a long-running SELECT in READ
COMMITTED mode were prone to see data from various points in time, data
produced by intervening commits. Turned out that yes, which is why you
should prefer SNAPSHOT (the default) if that matters to you.

READ ONLY READ COMMITTED and consistency - 2010-05-16
http://tech.dir.groups.yahoo.com/group/firebird-support/message/108522

Now I'm just reading a book on Oracle and found the definition of READ
COMMITTED to be different. In fact, it does afford exactly what I was
wondering existed or not in Firebird, and it also has a term for it:
Statement-Level Read Consistency. Here's the reference:

Oracle® Database Concepts
10g Release 2 (10.2)
Part Number B14220-02

13 Data Concurrency and Consistency
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/consist.htm

No further questions, just informational, perhaps mainly for myself. :-)

I haven't read the standards (and don't know if they're available
online), so I don't know which version (if any) is closer or true
to the standard.

--
Michael Ludwig