I haven't looked in great detail into why this is happpening, but it seems as though processNamePattern() doesn't handle ?'s correctly in the negative lookahead context correctly.
Negative lookahead context!? You are several sigmas beyond the subset of regex functionality that \d and friends are intended to support. Given that we're defining * and ? as shell-style wildcards, it's not going to be feasible to handle very much of ordinary regex usage let alone advanced.
I was worried you'd say as much. I'm in a situation where I've got a few hundred schemas floating around now and about half of them end with _log or _shadow and I was surprised at how non-trivial it was to filter out the _log or _shadow schemas with \dn. I tried thinking up the psql equiv of tcsh's fignore but had no luck (ex: set fignore = (\~ .o .bak)).
The more I think about this, a leading pipe could be used to pipe the output to a utility, so that \dn | egrep -v '(log|shadow) would work and would be the easiest solution.
This on the other hand seems more like a potentially useful feature, although I'm unclear on what you expect to get sent through the pipe exactly --- you want column headers for instance? What if you're using a nondefault display layout?
Instead of using printf(), fprintf(), fwrite(), or whatever it is that psql(1) uses internally for displaying result sets, have it use the following chunk of pseudo code:
if (pipe_symbol_found) {
char buf[8192];
size_t len = 0;
memset(&buf, 0, sizeof(buf));fh = popen(..., "r+"); /* or setsocketpair() + fork() */
fwrite(formatted_output_buffer, strlen(formatted_output_buffer), 1, fh);
while((len = read(fileno(fh), buf, sizeof(buf)))) {
fwrite(buf, len, 1, stdout);
}
} else {
/* whatever the current code does */
}That doesn't take into account the set option that lets you write the output to a file, but that is trivial to handle. To answer your question, I'd send _everything_ through the pipe and use the pipe as a blanket IO filter. I haven't thought about this, but would it be possible to hand the data off to sh(1) and have it handle the pipe/redirection foo that way psql doesn't have to have any pipe/redirection brains? If so, I think that'd be slick since you could do things like '\dn | tail -n +3 | grep -v blah' to handle your concern about having the header sent through and a utility not wanting it.
Too bad tee(1) doesn't support a -p option to have tee(1)'s argument sent to sh(1) or a pipe instead of a file, then there'd be some real interesting things that one could script. Ex:
\dn | tee -p 'head -n 3 >> /dev/stdout' | tail -n +3 | egrep -v '_(log|shadow)$'
Which'd show you the header, but everything after the header would be sent to egrep(1). I can't understand why win32 users think *NIX's CLI can be confusing.... *grin*.
Just some thoughts. -sc
-- Sean Chittenden
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