On Tue, Jan 14, 2020 at 4:12 AM Tom Lane wrote:
>
> John Naylor writes:
> > [ v11 patch ]
>
> I pushed this with some small cosmetic adjustments.
Thanks for your help hacking on the token filter.
--
John Naylorhttps://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support,
John Naylor writes:
> [ v11 patch ]
I pushed this with some small cosmetic adjustments.
One non-cosmetic adjustment I experimented with was to change
str_udeescape() to overwrite the source string in-place, since
we know that's modifiable storage and de-escaping can't make
the string longer. I
On Mon, Jan 13, 2020 at 7:57 AM Tom Lane wrote:
>
> Hmm ... after a bit of research I agree that these functions are not
> a portability hazard. They are present at least as far back as flex
> 2.5.33 which is as old as we've got in the buildfarm.
>
> However, I'm less excited about them from a
John Naylor writes:
>> I no longer use state variables to track scanner state, and in fact I
>> removed the existing "state_before" variable in ECPG. Instead, I used
>> the Flex builtins yy_push_state(), yy_pop_state(), and yy_top_state().
>> These have been a feature for a long time, it seems,
I wrote:
> I no longer use state variables to track scanner state, and in fact I
> removed the existing "state_before" variable in ECPG. Instead, I used
> the Flex builtins yy_push_state(), yy_pop_state(), and yy_top_state().
> These have been a feature for a long time, it seems, so I think we're
On Tue, Nov 26, 2019 at 10:32 PM Tom Lane wrote:
> I haven't looked closely at what ecpg does with the processed
> identifiers. If it just spits them out as-is, a possible solution
> is to not do anything about de-escaping, but pass the sequence
> U&"..." (plus UESCAPE ... if any), just like
John Naylor writes:
> It seems something is not quite right in v9 with the error position reporting:
> SELECT U&'wrong: +0061' UESCAPE '+';
> ERROR: invalid Unicode escape character at or near "'+'"
> LINE 1: SELECT U&'wrong: +0061' UESCAPE '+';
> -^
>
On Tue, Nov 26, 2019 at 5:51 AM Tom Lane wrote:
>
> [ My apologies for being so slow to get back to this ]
No worries -- it's a nice-to-have, not something our users are excited about.
> It struck me though that there's another solution we haven't discussed,
> and that's to make the token
[ My apologies for being so slow to get back to this ]
John Naylor writes:
> Now that I think of it, the regression in v7 was largely due to the
> fact that the parser has to call the lexer 3 times per string in this
> case, and that's going to be slower no matter what we do.
Ah, of course.
Alvaro Herrera writes:
> ... it seems this patch needs attention, but I'm not sure from whom.
> The tests don't pass whenever the server encoding is not UTF8, so I
> suppose we should either have an alternate expected output file to
> account for that, or the tests should be removed. But anyway
... it seems this patch needs attention, but I'm not sure from whom.
The tests don't pass whenever the server encoding is not UTF8, so I
suppose we should either have an alternate expected output file to
account for that, or the tests should be removed. But anyway the code
needs to be reviewed.
On Thu, Aug 1, 2019 at 8:51 PM John Naylor wrote:
> select U&'\de04\d83d'; -- surrogates in wrong order
> -psql:test_unicode.sql:10: ERROR: invalid Unicode surrogate pair at
> or near "U&'\de04\d83d'"
> +psql:test_unicode.sql:10: ERROR: invalid Unicode surrogate pair
> LINE 1: select
On Mon, Jul 29, 2019 at 10:40 PM Tom Lane wrote:
>
> John Naylor writes:
>
> > The lexer returns UCONST from xus and UIDENT from xui. The grammar has
> > rules that are effectively:
>
> > SCONST { do nothing}
> > | UCONST { esc char is backslash }
> > | UCONST UESCAPE SCONST { esc char is from
John Naylor writes:
> On Sun, Jul 21, 2019 at 3:14 AM Tom Lane wrote:
>> So I'm feeling like maybe we should experiment to see what that
>> solution looks like, before we commit to going in this direction.
>> What do you think?
> Given the above wrinkles, I thought it was worth trying. Attached
Chapman Flack writes:
> On 07/24/19 03:45, John Naylor wrote:
>> On Sun, Jul 21, 2019 at 3:14 AM Tom Lane wrote:
>>> However, my second reaction was that maybe you were on to something
>>> upthread when you speculated about postponing de-escaping of
>>> Unicode literals into the grammar. If we
On 07/24/19 03:45, John Naylor wrote:
> On Sun, Jul 21, 2019 at 3:14 AM Tom Lane wrote:
>> However, my second reaction was that maybe you were on to something
>> upthread when you speculated about postponing de-escaping of
>> Unicode literals into the grammar. If we did it like that then
Wow,
On Sun, Jul 21, 2019 at 3:14 AM Tom Lane wrote:
>
> John Naylor writes:
> > The pre-existing ecpg var "state_before" was a bit confusing when
> > combined with the new var "state_before_quote_stop", and the former is
> > also used with C-comments, so I decided to go with
> >
John Naylor writes:
> The pre-existing ecpg var "state_before" was a bit confusing when
> combined with the new var "state_before_quote_stop", and the former is
> also used with C-comments, so I decided to go with
> "state_before_lit_start" and "state_before_lit_stop". Even though
> comments
On Wed, Jul 10, 2019 at 3:15 AM Tom Lane wrote:
>
> John Naylor writes:
> > [ v4 patches for trimming lexer table size ]
>
> I reviewed this and it looks pretty solid. One gripe I have is
> that I think it's best to limit backup-prevention tokens such as
> quotecontinuefail so that they match
John Naylor writes:
> [ v4 patches for trimming lexer table size ]
I reviewed this and it looks pretty solid. One gripe I have is
that I think it's best to limit backup-prevention tokens such as
quotecontinuefail so that they match only exact prefixes of their
"success" tokens. This seems
On Wed, Jul 3, 2019 at 5:35 AM Tom Lane wrote:
>
> As far as I can see, the point of 0002 is to have just one set of
> flex rules for the various variants of quotecontinue processing.
> That sounds OK, though I'm a bit surprised it makes this much difference
> in the table size. I would suggest
On Wed, Jul 3, 2019 at 5:35 AM Tom Lane wrote:
>
> John Naylor writes:
> > 0001 is a small patch to remove some unneeded generality from the
> > current rules. This lowers the number of elements in the yy_transition
> > array from 37045 to 36201.
>
> I don't particularly like 0001. The two bits
John Naylor writes:
> 0001 is a small patch to remove some unneeded generality from the
> current rules. This lowers the number of elements in the yy_transition
> array from 37045 to 36201.
I don't particularly like 0001. The two bits like this
-whitespace ({space}+|{comment})
I wrote:
> > I found a possible other way to bring the size of the transition table
> > under 32k entries while keeping the existing no-backup rules in place:
> > Replace the "quotecontinue" rule with a new state. In the attached
> > draft patch, when Flex encounters a quote while inside any kind
I wrote:
> > I'll look for other rules that could be more
> > easily optimized, but I'm not terribly optimistic.
>
> I found a possible other way to bring the size of the transition table
> under 32k entries while keeping the existing no-backup rules in place:
> Replace the "quotecontinue" rule
I wrote:
> I'll look for other rules that could be more
> easily optimized, but I'm not terribly optimistic.
I found a possible other way to bring the size of the transition table
under 32k entries while keeping the existing no-backup rules in place:
Replace the "quotecontinue" rule with a new
Hi,
On 2019-06-20 10:52:54 -0400, Tom Lane wrote:
> John Naylor writes:
> > It would be nice to have confirmation to make sure I didn't err
> > somewhere, and to try a more real-world benchmark.
>
> I don't see much wrong with using information_schema.sql as a parser/lexer
> benchmark case. We
John Naylor writes:
> I decided to do some experiments with how we use Flex. The main
> takeaway is that backtracking, which we removed in 2005, doesn't seem
> to matter anymore for the core scanner. Also, state table size is of
> marginal importance.
Huh. That's really interesting, because
I decided to do some experiments with how we use Flex. The main
takeaway is that backtracking, which we removed in 2005, doesn't seem
to matter anymore for the core scanner. Also, state table size is of
marginal importance.
Using the information_schema Flex+Bison microbenchmark from Tom [1], I
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