Executing (II) against pg 8.4.4 or 9.0.4 yields 'BEFORE', but in order for 9.1.7 to yield the same one has to execute (I) .. bummer
This has nothing to do with regexp's. It's a change in how '\' is interpreted in any quoted string. The change came with Postgres 9.x and is documented in the release notes. It brings Postgres into compliance with the SQL standard.
In Perl, I do something like this:
my $pg_bs_char; if ($dbh->get_info($GetInfoType{SQL_DBMS_VER}) gt "09.00.00") { $pg_bs_char = "\\"; # a single '\' for PG 9.1 and higher } else { $pg_bs_char = "\\\\"; # a double '\\' for PG up to 9.0 }
You can also revert to the old 8.x interpretation; see