On Thu, Jun 27, 2013 at 11:28 AM, Dean Rasheed <dean.a.rash...@gmail.com> wrote: > On 26 June 2013 21:46, Peter Eisentraut <pete...@gmx.net> wrote: >> On 6/26/13 4:04 PM, Dean Rasheed wrote: >>> A quick google search reveals several people asking for something like >>> this, and people recommending md5(string_agg(...)) or >>> md5(string_agg(md5(...))) based solutions, which are doomed to failure >>> on larger tables. >> >> The thread discussed several other options of checksumming tables that >> did not have the air of a crytographic offering, as Noah put it. >> > > True but md5 has the advantage of being directly comparable with the > output of Unix md5sum, which would be useful if you loaded data from > external files and wanted to confirm that your import process didn't > mangle it.
The problem with md5_agg() is that it's only useful in toy scenarios. It's more useful give people script that does same sum(hash(row)) on dump file than try to run MD5 on ordered rows. Also, I don't think anybody actually cares about MD5(table-as-bytes), instead people want way to check if 2 tables or table and dump are same. -- marko -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers