On Mon, Feb 20, 2017 at 03:44:49PM -0500, Tom Lane wrote: > > where table.*::text = (saved from select). > > > If the row was changed between the time it was first read and updated, the > > update will do touch any rows as the ::text will be different. > > > Why can't we use xmin and xmax columns to achieve the same. > > Well, that doesn't do quite the same thing: the cookbook query will > proceed if there was a no-op update in between (or maybe even two updates > that canceled each other out). If you look at xmin then you won't proceed > in such cases. I could imagine either behavior being "right" depending on > your application needs.
Also a consideration: table.*::text may become quite unwieldy if there's one or more BYTEA columns in the table. Karsten -- GPG key ID E4071346 @ eu.pool.sks-keyservers.net E167 67FD A291 2BEA 73BD 4537 78B9 A9F9 E407 1346 -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
