Jeff Janes <jeff.janes@xxxxxxxxx> writes: > On Sun, Nov 18, 2012 at 4:35 PM, Vick Khera <vivek@xxxxxxxxx> wrote: >> On Sun, Nov 18, 2012 at 7:24 PM, Craig Ringer <craig@xxxxxxxxxxxxxxx> wrote: >>> That depends on the PostgreSQL version. Some changes were made to improve >>> that recently; from memory, it used to require rewriting, so people would >>> sometimes work around it with (dodgy and unsafe) hacks directly to the >>> system catalogs. I'm not sure if "recently" is 9.2 or 9.3. > Just looking at the timing of the below, I'd say the optimization of > varchar(n) to text took place in 9.1. 9.1 is bright enough to optimize that specific case; 9.2 covers some additional cases like varchar(m) to varchar(n) for m <= n. I think also that 9.2 avoids rebuilding indexes on the affected column in some of these cases, but 9.1 did not. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
