-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Michael Fuhr wrote: >What words in section 12.2.1 are you referring to? I see the >following (emphasis mine): > > In effect, a SELECT query sees a snapshot of the database as of > the instant that that *query* begins to run. Notice that two > successive SELECT commands can see different data, even though > they are within a single transaction, if other transactions commit > changes during execution of the first SELECT. > > Apologies for the confusion. Indeed the documentation is right. I confused "start of query" with "start of transaction". For my curiosity, what is the reason that in read comitted mode MVCC can guarantee a consistent snapshot durign a query, while in serializable mode MVCC can guarantee it for a longer interval (the entire transaction). Are these different MVCC implementations, or is some kind of locking performed when executing queries in read committed mode? Thanks, Geert -----BEGIN PGP SIGNATURE----- Version: PGP Desktop 9.0.1 (Build 2185) iQEVAwUBQs/izprPkVOV4lDgAQLpFggAqbxaFnMfajg94aaUcWF/IK0ZlEuEVVGl 2hmb295ukCGOV7IjhMFocCQMWxLHcAuwP4vBJM/Dkcy9HW7PGCM6XWJyWbQMYHcn iWZAw/p2bllxByEe6xli+J2VdeZAohHPixRibLa+uqCE594o2NPK8g06HmPz28rb noZefXv0+4rGI4Nlw03bLbt80WV2+bYkLFfDveEHt8tx93KS8p+cfv+KL7sFwtzK 1ZbSm1TEdCmPfLAo8UI5YZKJtHA58XoW89WTgACATz04TNHMzni+U5ToMqX4tKOI 6AniwTocjko9Nt+ul8CFquOOoyk7WlOVrtUXpUAg4QEsBMA503Z3uA== =JBQU -----END PGP SIGNATURE----- ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
