This gets us to a point where psqlscan.l can be used by other frontend
programs for the same purpose psql uses it for, ie to detect when it's
collected a complete SQL command from input that is divided across
line boundaries. Moreover, other programs can supply their own lexers
for backslash commands of their own choosing. A follow-on patch will
use this in pgbench.
The end result here is roughly the same as in Kyotaro Horiguchi's
0001-Make-SQL-parser-part-of-psqlscan-independent-from-ps.patch, although
the details of the method for switching between lexers are quite different.
Basically, in this patch we share the entire PsqlScanState, YY_BUFFER_STATE
stack, *and* yyscan_t between different lexers. The only thing we need
to do to switch to a different lexer is to make sure the start_state is
valid for the new lexer. This works because flex doesn't keep any other
persistent state that depends on the specific lexing tables generated for
a particular .l file. (We are assuming that both lexers are built with
the same flex version, or at least versions that are compatible with
respect to the contents of yyscan_t; but that doesn't seem likely to
be a big problem in practice, considering how slowly flex changes.)
Aside from being more efficient than Horiguchi-san's original solution,
this avoids possible corner-case changes in semantics: the original code
was capable of popping the input buffer stack while still staying in
backslash-related parsing states. I'm not sure that that equates to any
useful user-visible behaviors, but I'm not sure it doesn't either, so
I'm loath to assume that we only need to consider the topmost buffer when
parsing a backslash command.
I've attempted to update the MSVC build scripts for the added .l file,
but will rely on the buildfarm to see if I missed anything.
Kyotaro Horiguchi and Tom Lane
Change psqlscan.l to specify '%option reentrant', adjust internal APIs
to match, and get rid of its internal static variables. While this is
good cleanup in an abstract sense, the reason to do it right now is that
it seems the only practical way to support use of separate flex lexers
with common PsqlScanState infrastructure. If we build two non-reentrant
lexers then we are going to have problems with dangling buffer pointers
in whichever lexer isn't active when we transition from one buffer to
another, as well as curious side-effects if we try to share any code
between the files. (Horiguchi-san had a different solution to that in his
pending patch, but I find it ugly and probably broken for corner cases.)
Depending on which version of flex you're using, this may result in getting
a "warning: unused variable 'yyg'" warning from psqlscan, similar to the
one you'd have seen for a long time in backend/parser/scan.l. I put a
local -Wno-error into CFLAGS for the file, for the convenience of those
who compile with -Werror.
Also, stop compiling psqlscan as part of mainloop.c, and make it a
standalone build target instead. This is a lot cleaner than before, though
it doesn't really change much in practice as of this commit. (I'm not sure
whether the MSVC build scripts will need some help with this part, but the
buildfarm will soon tell us.)
Remove assorted external references from psqlscan.l in preparation for
making it usable by other frontend programs. This mostly involves
getting rid of direct calls to psql_error() and GetVariable() in favor
of introducing a callback-functions struct to encapsulate variable
fetching and error printing. In addition, pass the current encoding
and standard-strings status as additional parameters to psql_scan_setup
instead of looking directly at "pset" or calling additional functions.
I did not bother to change some references to psql_error that are in
functions that will soon migrate to a psql-specific backslash-command
lexer. Other than that, this version of psqlscan.l is capable of
compiling standalone. It still depends on assorted src/common functions
as well as some encoding-related libpq functions, but we expect that
all programs using it will be happy with those dependencies.
Kyotaro Horiguchi, somewhat editorialized on by me
While the SQL standard is pretty vague on the overall topic of operator
precedence (because it never presents a unified BNF for all expressions),
it does seem reasonable to conclude from the spec for <boolean value
expression> that OR has the lowest precedence, then AND, then NOT, then IS
tests, then the six standard comparison operators, then everything else
(since any non-boolean operator in a WHERE clause would need to be an
argument of one of these).
We were only sort of on board with that: most notably, while "<" ">" and
"=" had properly low precedence, "<=" ">=" and "<>" were treated as generic
operators and so had significantly higher precedence. And "IS" tests were
even higher precedence than those, which is very clearly wrong per spec.
Another problem was that "foo NOT SOMETHING bar" constructs, such as
"x NOT LIKE y", were treated inconsistently because of a bison
implementation artifact: they had the documented precedence with respect
to operators to their right, but behaved like NOT (i.e., very low priority)
with respect to operators to their left.
Fixing the precedence issues is just a small matter of rearranging the
precedence declarations in gram.y, except for the NOT problem, which
requires adding an additional lookahead case in base_yylex() so that we
can attach a different token precedence to NOT LIKE and allied two-word
operators.
The bulk of this patch is not the bug fix per se, but adding logic to
parse_expr.c to allow giving warnings if an expression has changed meaning
because of these precedence changes. These warnings are off by default
and are enabled by the new GUC operator_precedence_warning. It's believed
that very few applications will be affected by these changes, but it was
agreed that a warning mechanism is essential to help debug any that are.
Commit 865f14a2d3 was quite a few bricks
shy of a load: psql, ecpg, and plpgsql were all left out-of-step with
the core lexer. Of these only the last was likely to be a fatal
problem; but still, a minimal amount of grepping, or even just reading
the comments adjacent to the places that were changed, would have found
the other places that needed to be changed.
Commit a5ff502fce was a brick shy of a load
in the backend lexer too, not just psql. Per further testing of bug #9068.
In passing, improve related comments.
Even though this patch had no user-visible difference, better keep the code
in psqlscan.l sync with the backend lexer. And of course it's nice to shrink
the psql binary, too. Ecpg's version of the lexer doesn't have the error
rule, it doesn't try to avoid backing up, so it doesn't need to be modified.
As reminded by Tom Lane
client encoding and the client encoding is not *safe* one. Such an
example is, file encoding is UTF-8 and client encoding SJIS. Patch
contributed by Jiang Guiqing.
We had a number of variants on the theme of "malloc or die", with the
majority named like "pg_malloc", but by no means all. Standardize on the
names pg_malloc, pg_malloc0, pg_realloc, pg_strdup. Get rid of pg_calloc
entirely in favor of using pg_malloc0.
This is an essentially cosmetic change, so no back-patch. (I did find
a couple of places where psql and pg_dump were using plain malloc or
strdup instead of the pg_ versions, but they don't look significant
enough to bother back-patching.)
For those variables only used when asserts are enabled, use a new
macro PG_USED_FOR_ASSERTS_ONLY, which expands to
__attribute__((unused)) when asserts are not enabled.
These changes allow backtick command evaluation and psql variable
interpolation to happen on substrings of a single meta-command argument.
Formerly, no such evaluations happened at all if the backtick or colon
wasn't the first character of the argument, and we considered an argument
completed as soon as we'd processed one backtick, variable reference, or
quoted substring. A string like 'FOO'BAR was thus taken as two arguments
not one, not exactly what one would expect. In the new coding, an argument
is considered terminated only by unquoted whitespace or backslash.
Also, clean up a bunch of omissions, infelicities and outright errors in
the psql documentation of variables and metacommand argument syntax.
Per previous experimentation, backtracking slows down lexing performance
significantly (by about a third). It's usually pretty easy to avoid, just
need to have rules that accept an incomplete construct and do whatever the
lexer would have done otherwise.
The backtracking was introduced by the patch that added quoted variable
substitution. Back-patch to 9.0 where that was added.
This warning is new in gcc 4.6 and part of -Wall. This patch cleans
up most of the noise, but there are some still warnings that are
trickier to remove.
Original patch failed to include new exclusive states in a switch that
needed to include them; and also was guilty of very fuzzy thinking
about how to handle error cases. Per bug #5729 from Alan Choi.
"val AS name" to "name := val", as per recent discussion.
This patch catches everything in the original named-parameters patch,
but I'm not certain that no other dependencies snuck in later (grepping
the source tree for all uses of AS soon proved unworkable).
In passing I note that we've dropped the ball at least once on keeping
ecpg's lexer (as opposed to parser) in sync with the backend. It would
be a good idea to go through all of pgc.l and see if it's in sync now.
I didn't attempt that at the moment.
refers to itself (directly or indirectly). Instead, print a message when
recursion is detected, and don't expand the repeated reference. Per bug
#5448 from Francis Markham.
Back-patch to 8.0. Although the issue exists in 7.4 as well, it seems
impractical to fix there because of the lack of any state stack that
could be used to track active expansions.
directly. This was a lot of trouble, but should be worth it in terms of
not having to keep the plpgsql lexer in step with core anymore. In addition
the handling of keywords is significantly better-structured, allowing us to
de-reserve a number of words that plpgsql formerly treated as reserved.
results (ie, an empty "broken" buffer) if memory overrun occurs anywhere
along the way to filling the buffer. The previous coding would just silently
discard portions of the intended buffer contents, as exhibited in trouble
report from Sam Mason. Also, tweak psql's main loop to correctly detect
and report such overruns. There's probably much more that should be done
in this line, but this is a start.
This has been the only documented and encouraged syntax for a long time, and
with extension facilities such as aliases being proposed, it is a good time to
clean up the legacy syntax a bit.
Author: Bernd Helmle <mailings@oopsware.de>
renumbering of encoding IDs done between 8.2 and 8.3 turns out to break 8.2
initdb and psql if they are run with an 8.3beta1 libpq.so. For the moment
we can rearrange the order of enum pg_enc to keep the same number for
everything except PG_JOHAB, which isn't a problem since there are no direct
references to it in the 8.2 programs anyway. (This does force initdb
unfortunately.)
Going forward, we want to fix things so that encoding IDs can be changed
without an ABI break, and this commit includes the changes needed to allow
libpq's encoding IDs to be treated as fully independent of the backend's.
The main issue is that libpq clients should not include pg_wchar.h or
otherwise assume they know the specific values of libpq's encoding IDs,
since they might encounter version skew between pg_wchar.h and the libpq.so
they are using. To fix, have libpq officially export functions needed for
encoding name<=>ID conversion and validity checking; it was doing this
anyway unofficially.
It's still the case that we can't renumber backend encoding IDs until the
next bump in libpq's major version number, since doing so will break the
8.2-era client programs. However the code is now prepared to avoid this
type of problem in future.
Note that initdb is no longer a libpq client: we just pull in the two
source files we need directly. The patch also fixes a few places that
were being sloppy about checking for an unrecognized encoding name.
throw warnings for 100%-SQL-standard constructs, clean up some minor
infelicities, try to un-break ecpg to the best of my ability. (It's not clear
how ecpg is going to find out the setting of standard_conforming_strings,
though.) I think pg_dump still needs work, too.
with main, avoid using a SQL-defined SQLSTATE for what is most definitely
not a SQL-compatible error condition, fix documentation omissions,
adhere to message style guidelines, don't use two GUC_REPORT variables
when one is sufficient. Nothing done about pg_dump issues.
Tom Lane
Bruce Momjian
Heikki Linnakangas
Andrew Dunstan
Tatsuo Ishii
Peter Eisentraut
Magnus Hagander
Robert Haas