Re: reducing the footprint of ScanKeyword (was Re: Large writable variables)

On Wed, Jan 9, 2019 at 2:04 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> I wrote:
> > John Naylor <john.naylor@2ndquadrant.com> writes:
> >> -There is a bit of a cognitive clash between $case_sensitive in
> >> gen_keywordlist.pl and $case_insensitive in PerfectHash.pm. They each
> >> make sense in their own file, but might it be worth using one or the
> >> other?

> Working on the fmgr-oid-lookup idea gave me the thought that
> PerfectHash.pm ought to support fixed-length keys.  Rather than start
> adding random parameters to the function, I borrowed an idea from
> PostgresNode.pm and made the options be keyword-style parameters.  Now
> the impedance mismatch about case sensitivity is handled with
>
> my $f = PerfectHash::generate_hash_function(\@keywords, $funcname,
>         case_insensitive => !$case_sensitive);
>
> which is at least a little clearer than before, though I'm not sure
> if it entirely solves the problem.

It's a bit clearer, but thinking about this some more, it makes sense
for gen_keywordlist.pl to use $case_insensitive, because right now
every instance of the var is "!$case_sensitive". In the attached (on
top of v4), I change the command line option to --citext, and add the
ability to negate it within the option, as '--no-citext'. It's kind of
a double negative for the C-keywords invocation, but we can have the
option for both cases, so we don't need to worry about what the
default is (which is case_insensitive=1).

--
John Naylor                https://www.2ndQuadrant.com/
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