On Tue, Sep 02, 2014 at 09:49:56AM -0400, Tom Lane wrote: > Noah Misch <n...@leadboat.com> writes: > > I'm with you that far. Given a patch that does not change "\s /tmp/foo" and > > that makes "\s" equivalent to "\s /tmp/foo" + "\! cat /tmp/foo >/dev/tty", > > back-patch by all means. No patch posted on this thread is so surgical, > > hence > > my objection. In particular, your latest patch revision changes "\s > > /tmp/foo" > > to match the novel output the patch introduces for plain "\s". "\s > > /tmp/foo" > > would no longer write data that libedit can reload as a history file. > > BTW, I failed last night to produce a coherent argument against that > particular point, but consider this. What are the main use-cases for > \s to a file? I argue that they are > > 1. Create a human-readable record of what you did. > 2. Create the starting point for a SQL script file. > > I do not deny it's possible that somebody out there is also using \s for > > 3. Create a file that I can overwrite ~/.psql_history with later. > > But if this is being done in the field at all, surely it is miles behind > the applications listed above.
I'm unprepared to speculate about the relative prevalence of those use cases. > Now, if you are using libreadline, the output of \s has always been > perfectly fit for purposes 1 and 2, because it's plain text of the > history entries. Moreover, it is *not* particularly fit for purpose 3, > because intra-command newlines aren't encoded. Yes, you could get > libreadline to read the file, but multiline SQL commands will be seen > as multiple history entries which is very far from convenient to use. > (This adds to my suspicion that nobody is doing #3 in practice.) > > On the other hand, if you are using libedit, purpose 3 works great > but the output is utterly unfit for either purpose 1 or 2. Here > are the first few lines of ~/.psql_history on one of my Macs: > > _HiStOrY_V2_ > explain\040verbose\^A\040\040select\0401\^Aunion\^A\040\040select\0402; > \\q > select\0404; > explain\040verbose\^A\040\040select\0401\^Aunion\^A\040\040select\0402; > select\04044; > \\q > \\s > \\s\040foobar > \\q > > What the proposed patch does is ensure that \s produces plain text > regardless of which history library you are using. I think arguing > that we shouldn't do that is stretching the concept of backwards > compatibility well past the breaking point. Given the negligible urgency to improve \s, the slightest compatibility hazard justifies punting this work from back-patch to master-only. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers