Second thoughts about commit 824bf7190: we apply makesearch() to
an NFA after having determined whether it is a MATCHALL pattern.
Prepending ".*" doesn't make it non-MATCHALL, but it does change the
maximum possible match length, and makesearch() failed to update that.
This has no ill effects given the stylized usage of search NFAs, but
it seems like it's better to keep the data structure consistent. In
particular, fixing this allows more honest handling of the MATCHALL
check in matchuntil(): we can now assert that maxmatchall is infinity,
instead of lamely assuming that it should act that way.
In passing, improve the code in dump[c]nfa so that infinite maxmatchall
is printed as "inf" not a magic number.
Commit 824bf7190 introduced a new search of the NFAs generated by
regex compilation. I failed to think hard about the performance
characteristics of that search, with the predictable outcome
that it's bad: weird regexes can trigger exponential search time.
Worse, there's no check-for-interrupt in that code, so you can't
even cancel the query if this happens.
Fix by introducing memo-ization of the search results, so that any one
NFA state need be examined in detail just once. This potentially uses
a lot of memory, but we can bound the memory usage by putting a limit
on the number of states for which we'll try to prove match-all-ness.
That is sane because we already have a limit (DUPINF) on the maximum
finite string length that a matchall regex can match; and patterns
that involve much more than DUPINF states would probably exceed that
limit anyway.
Also, rearrange the logic so that we check the basic is-the-graph-
all-RAINBOW-arcs property before we start the recursive search to
determine path lengths. This will ensure that we fall out quickly
whenever the NFA couldn't possibly be matchall.
Also stick in a check-for-interrupt, just in case these measures
don't completely eliminate the risk of slowness.
Discussion: https://postgr.es/m/3483895.1619898362@sss.pgh.pa.us
POSIX defines the behavior of back-references thus:
The back-reference expression '\n' shall match the same (possibly
empty) string of characters as was matched by a subexpression
enclosed between "\(" and "\)" preceding the '\n'.
As far as I can see, the back-reference is supposed to consider only
the data characters matched by the referenced subexpression. However,
because our engine copies the NFA constructed from the referenced
subexpression, it effectively enforces any constraints therein, too.
As an example, '(^.)\1' ought to match 'xx', or any other string
starting with two occurrences of the same character; but in our code
it does not, and indeed can't match anything, because the '^' anchor
constraint is included in the backref's copied NFA. If POSIX intended
that, you'd think they'd mention it. Perl for one doesn't act that
way, so it's hard to conclude that this isn't a bug.
Fix by modifying the backref's NFA immediately after it's copied from
the reference, replacing all constraint arcs by EMPTY arcs so that the
constraints are treated as automatically satisfied. This still allows
us to enforce matching rules that depend only on the data characters;
for example, in '(^\d+).*\1' the NFA matching step will still know
that the backref can only match strings of digits.
Perhaps surprisingly, this change does not affect the results of any
of a rather large corpus of real-world regexes. Nonetheless, I would
not consider back-patching it, since it's a clear compatibility break.
Patch by me, reviewed by Joel Jacobson
Discussion: https://postgr.es/m/661609.1614560029@sss.pgh.pa.us
The previous logic here created a separate pool of arcs for each
state, so that the out-arcs of each state were physically stored
within it. Perhaps this choice was driven by trying to not include
a "from" pointer within each arc; but Spencer gave up on that idea
long ago, and it's hard to see what the value is now. The approach
turns out to be fairly disastrous in terms of memory consumption,
though. In the first place, NFAs built by this engine seem to have
about 4 arcs per state on average, with a majority having only one
or two out-arcs. So pre-allocating 10 out-arcs for each state is
already cause for a factor of two or more bloat. Worse, the NFA
optimization phase moves arcs around with abandon. In a large NFA,
some of the states will have hundreds of out-arcs, so towards the
end of the optimization phase we have a significant number of states
whose arc pools have room for hundreds of arcs each, even though only
a few of those arcs are in use. We have seen real-world regexes in
which this effect bloats the memory requirement by 25X or even more.
Hence, get rid of the per-state arc pools in favor of a single arc
pool for the whole NFA, with variable-sized allocation batches
instead of always asking for 10 at a time. While we're at it,
let's batch the allocations of state structs too, to further reduce
the malloc traffic.
This incidentally allows moveouts() to be optimized in a similar
way to moveins(): when moving an arc to another state, it's now
valid to just re-link the same arc struct into a different outchain,
where before the code invariants required us to make a physically
new arc and then free the old one.
These changes reduce the regex compiler's typical space consumption
for average-size regexes by about a factor of two, and much more for
large or complicated regexes. In a large test set of real-world
regexes, we formerly had half a dozen cases that failed with "regular
expression too complex" due to exceeding the REG_MAX_COMPILE_SPACE
limit (about 150MB); we would have had to raise that limit to
something close to 400MB to make them work with the old code. Now,
none of those cases need more than 13MB to compile. Furthermore,
the test set is about 10% faster overall due to less malloc traffic.
Discussion: https://postgr.es/m/168861.1614298592@sss.pgh.pa.us
gcc 10 is smart enough to notice that control could reach this
"hasmatch[depth]" assignment with depth < 0, but not smart enough
to know that that would require a badly broken NFA graph. Change
the assert() to a plain runtime test to shut it up.
Per report from Andres Freund.
Discussion: https://postgr.es/m/20210223173437.b3ywijygsy6q42gq@alap3.anarazel.de
This builds on the previous "rainbow" patch to detect NFAs that will
match any string, though possibly with constraints on the string length.
This definition is chosen to match constructs such as ".*", ".+", and
".{1,100}". Recognizing such an NFA after the optimization pass is
fairly cheap, since we basically just have to verify that all arcs
are RAINBOW arcs and count the number of steps to the end state.
(Well, there's a bit of complication with pseudo-color arcs for string
boundary conditions, but not much.)
Once we have these markings, the regex executor functions longest(),
shortest(), and matchuntil() don't have to expend per-character work
to determine whether a given substring satisfies such an NFA; they
just need to check its length against the bounds. Since some matching
problems require O(N) invocations of these functions, we've reduced
the runtime for an N-character string from O(N^2) to O(N). Of course,
this is no help for non-matchall sub-patterns, but those usually have
constraints that allow us to avoid needing O(N) substring checks in the
first place. It's precisely the unconstrained "match-all" cases that
cause the most headaches.
This is part of a patch series that in total reduces the regex engine's
runtime by about a factor of four on a large corpus of real-world regexes.
Patch by me, reviewed by Joel Jacobson
Discussion: https://postgr.es/m/1340281.1613018383@sss.pgh.pa.us
Some regular expression constructs, most notably the "." match-anything
metacharacter, produce a sheaf of parallel NFA arcs covering all
possible colors (that is, character equivalence classes). We can make
a noticeable improvement in the space and time needed to process large
regexes by replacing such cases with a single arc bearing the special
color code "RAINBOW". This requires only minor additional complication
in places such as pull() and push().
Callers of pg_reg_getoutarcs() must now be prepared for the possibility
of seeing a RAINBOW arc. For the one known user, contrib/pg_trgm,
that's a net benefit since it cuts the number of arcs to be dealt with,
and the handling isn't any different than for other colors that contain
too many characters to be dealt with individually.
This is part of a patch series that in total reduces the regex engine's
runtime by about a factor of four on a large corpus of real-world regexes.
Patch by me, reviewed by Joel Jacobson
Discussion: https://postgr.es/m/1340281.1613018383@sss.pgh.pa.us
Push some hopefully-uncontroversial bits extracted from an upcoming
patch series, to remove non-relevant clutter from the main patches.
In compact(), return immediately after setting REG_ASSERT error;
continuing the loop would just lead to assertion failure below.
(Ask me how I know.)
In parseqatom(), remove assertion that moresubs() did its job.
When moresubs actually did its job, this is redundant with that
function's final assert; but when it failed on OOM, this is an
assertion crash. We could avoid the crash by adding a NOERR()
check before the assertion, but it seems better to subtract code
than add it. (Note that there's a NOERR exit a few lines further
down, and nothing else between here and there requires moresubs
to have succeeded. So we don't really need an extra error exit.)
This is a live bug in assert-enabled builds, but given the very
low likelihood of OOM in moresub's tiny allocation, I don't think
it's worth back-patching.
On the other hand, it seems worthwhile to add an assertion that
our intended v->subs[subno] target is still null by the time we
are ready to insert into it, since there's a recursion in between.
In pg_regexec, ensure we fflush any debug output on the way out,
and try to make MDEBUG messages more uniform and helpful. (In
particular, ensure that all of them are prefixed with the subre's
id number, so one can match up entry and exit reports.)
Add some test cases in test_regex to improve coverage of lookahead
and lookbehind constraints. Adding these now is mainly to establish
that this is indeed the existing behavior.
Discussion: https://postgr.es/m/1340281.1613018383@sss.pgh.pa.us
When REG_DEBUG is defined, ensure that an un-filled "struct cnfa"
is all-zeroes, not just that it has nstates == 0. This is mainly
so that looking at "struct subre" structs in gdb doesn't distract
one with a lot of garbage fields during regex compilation.
Adjust some places that print debug output to have suitable fflush
calls afterwards.
In passing, correct an erroneous ancient comment: the concatenation
subre-s created by parsebranch() have op == '.' not ','.
Noted while fooling around with some regex performance improvements.
Change pg_bsd_indent to follow upstream rules for placement of comments
to the right of code, and remove pgindent hack that caused comments
following #endif to not obey the general rule.
Commit e3860ffa4d wasn't actually using
the published version of pg_bsd_indent, but a hacked-up version that
tried to minimize the amount of movement of comments to the right of
code. The situation of interest is where such a comment has to be
moved to the right of its default placement at column 33 because there's
code there. BSD indent has always moved right in units of tab stops
in such cases --- but in the previous incarnation, indent was working
in 8-space tab stops, while now it knows we use 4-space tabs. So the
net result is that in about half the cases, such comments are placed
one tab stop left of before. This is better all around: it leaves
more room on the line for comment text, and it means that in such
cases the comment uniformly starts at the next 4-space tab stop after
the code, rather than sometimes one and sometimes two tabs after.
Also, ensure that comments following #endif are indented the same
as comments following other preprocessor commands such as #else.
That inconsistency turns out to have been self-inflicted damage
from a poorly-thought-through post-indent "fixup" in pgindent.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
The new indent version includes numerous fixes thanks to Piotr Stefaniak.
The main changes visible in this commit are:
* Nicer formatting of function-pointer declarations.
* No longer unexpectedly removes spaces in expressions using casts,
sizeof, or offsetof.
* No longer wants to add a space in "struct structname *varname", as
well as some similar cases for const- or volatile-qualified pointers.
* Declarations using PG_USED_FOR_ASSERTS_ONLY are formatted more nicely.
* Fixes bug where comments following declarations were sometimes placed
with no space separating them from the code.
* Fixes some odd decisions for comments following case labels.
* Fixes some cases where comments following code were indented to less
than the expected column 33.
On the less good side, it now tends to put more whitespace around typedef
names that are not listed in typedefs.list. This might encourage us to
put more effort into typedef name collection; it's not really a bug in
indent itself.
There are more changes coming after this round, having to do with comment
indentation and alignment of lines appearing within parentheses. I wanted
to limit the size of the diffs to something that could be reviewed without
one's eyes completely glazing over, so it seemed better to split up the
changes as much as practical.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
pcolor was used to represent function arguments that are nominally of
type color, but when using a pre-ANSI C compiler would be passed as the
promoted integer type. We really don't need that anymore.
A lookbehind constraint is like a lookahead constraint in that it consumes
no text; but it checks for existence (or nonexistence) of a match *ending*
at the current point in the string, rather than one *starting* at the
current point. This is a long-requested feature since it exists in many
other regex libraries, but Henry Spencer had never got around to
implementing it in the code we use.
Just making it work is actually pretty trivial; but naive copying of the
logic for lookahead constraints leads to code that often spends O(N^2) time
to scan an N-character string, because we have to run the match engine
from string start to the current probe point each time the constraint is
checked. In typical use-cases a lookbehind constraint will be written at
the start of the regex and hence will need to be checked at every character
--- so O(N^2) work overall. To fix that, I introduced a third copy of the
core DFA matching loop, paralleling the existing longest() and shortest()
loops. This version, matchuntil(), can suspend and resume matching given
a couple of pointers' worth of storage space. So we need only run it
across the string once, stopping at each interesting probe point and then
resuming to advance to the next one.
I also put in an optimization that simplifies one-character lookahead and
lookbehind constraints, such as "(?=x)" or "(?<!\w)", into AHEAD and BEHIND
constraints, which already existed in the engine. This avoids the overhead
of the LACON machinery entirely for these rather common cases.
The net result is that lookbehind constraints run a factor of three or so
slower than Perl's for multi-character constraints, but faster than Perl's
for one-character constraints ... and they work fine for variable-length
constraints, which Perl gives up on entirely. So that's not bad from a
competitive perspective, and there's room for further optimization if
anyone cares. (In reality, raw scan rate across a large input string is
probably not that big a deal for Postgres usage anyway; so I'm happy if
it's linear.)
Revert our previous addition of "all" flags to copyins() and copyouts();
they're no longer needed, and were never anything but an unsightly hack.
Improve a couple of infelicities in the REG_DEBUG code for dumping
the NFA data structure, including adding code to count the total
number of states and arcs.
Add a couple of missed error checks.
Add some more documentation in the README file, and some regression tests
illustrating cases that exceeded the state-count limit and/or took
unreasonable amounts of time before this set of patches.
Back-patch to all supported branches.
This code previously counted the number of NFA states it created, and
complained if a limit was exceeded, so as to prevent bizarre regex patterns
from consuming unreasonable time or memory. That's fine as far as it went,
but the code paid no attention to how many arcs linked those states. Since
regexes can be contrived that have O(N) states but will need O(N^2) arcs
after fixempties() processing, it was still possible to blow out memory,
and take a long time doing it too. To fix, modify the bookkeeping to count
space used by both states and arcs.
I did not bother with including the "color map" in the accounting; it
can only grow to a few megabytes, which is not a lot in comparison to
what we're allowing for states+arcs (about 150MB on 64-bit machines
or half that on 32-bit machines).
Looking at some of the larger real-world regexes captured in the Tcl
regression test suite suggests that the most that is likely to be needed
for regexes found in the wild is under 10MB, so I believe that the current
limit has enough headroom to make it okay to keep it as a hard-wired limit.
In connection with this, redefine REG_ETOOBIG as meaning "regular
expression is too complex"; the previous wording of "nfa has too many
states" was already somewhat inapropos because of the error code's use
for stack depth overrun, and it was not very user-friendly either.
Back-patch to all supported branches.
The previous coding would create a new intermediate state every time it
wanted to interchange the ordering of two constraint arcs. Certain regex
features such as \Y can generate large numbers of parallel constraint arcs,
and if we needed to reorder the results of that, we created unreasonable
numbers of intermediate states. To improve matters, keep a list of
already-created intermediate states associated with the state currently
being considered by the outer loop; we can re-use such states to place all
the new arcs leading to the same destination or source.
I also took the trouble to redefine push() and pull() to have a less risky
API: they no longer delete any state or arc that the caller might possibly
have a pointer to, except for the specifically-passed constraint arc.
This reduces the risk of re-introducing the same type of error seen in
the failed patch for CVE-2007-4772.
Back-patch to all supported branches.
The previous coding took something like O(N^4) time to fully process a
chain of N EMPTY arcs. We can't really do much better than O(N^2) because
we have to insert about that many arcs, but we can do lots better than
what's there now. The win comes partly from using mergeins() to amortize
de-duplication of arcs across multiple source states, and partly from
exploiting knowledge of the ordering of arcs for each state to avoid
looking at arcs we don't need to consider during the scan. We do have
to be a bit careful of the possible reordering of arcs introduced by
the sort-merge coding of the previous commit, but that's not hard to
deal with.
Back-patch to all supported branches.
Change the singly-linked in-arc and out-arc lists to be doubly-linked,
so that arc deletion is constant time rather than having worst-case time
proportional to the number of other arcs on the connected states.
Modify the bulk arc transfer operations copyins(), copyouts(), moveins(),
moveouts() so that they use a sort-and-merge algorithm whenever there's
more than a small number of arcs to be copied or moved. The previous
method is O(N^2) in the number of arcs involved, because it performs
duplicate checking independently for each copied arc. The new method may
change the ordering of existing arcs for the destination state, but nothing
really cares about that.
Provide another bulk arc copying method mergeins(), which is unused as
of this commit but is needed for the next one. It basically is like
copyins(), but the source arcs might not all come from the same state.
Replace the O(N^2) bubble-sort algorithm used in carcsort() with a qsort()
call.
These changes greatly improve the performance of regex compilation for
large or complex regexes, at the cost of extra space for arc storage during
compilation. The original tradeoff was probably fine when it was made, but
now we care more about speed and less about memory consumption.
Back-patch to all supported branches.
It's possible to construct regular expressions that contain loops of
constraint arcs (that is, ^ $ AHEAD BEHIND or LACON arcs). There's no use
in fully traversing such a loop at execution, since you'd just end up in
the same NFA state without having consumed any input. Worse, such a loop
leads to infinite looping in the pullback/pushfwd stage of compilation,
because we keep pushing or pulling the same constraints around the loop
in a vain attempt to move them to the pre or post state. Such looping was
previously recognized in CVE-2007-4772; but the fix only handled the case
of trivial single-state loops (that is, a constraint arc leading back to
its source state) ... and not only that, it was incorrect even for that
case, because it broke the admittedly-not-very-clearly-stated API contract
of the pull() and push() subroutines. The first two regression test cases
added by this commit exhibit patterns that result in assertion failures
because of that (though there seem to be no ill effects in non-assert
builds). The other new test cases exhibit multi-state constraint loops;
in an unpatched build they will run until the NFA state-count limit is
exceeded.
To fix, remove the code added for CVE-2007-4772, and instead create a
general-purpose constraint-loop-breaking phase of regex compilation that
executes before we do pullback/pushfwd. Since we never need to traverse
a constraint loop fully, we can just break the loop at any chosen spot,
if we add clone states that can replicate any sequence of arc transitions
that would've traversed just part of the loop.
Also add some commentary clarifying why we have to have all these
machinations in the first place.
This class of problems has been known for some time --- we had a report
from Marc Mamin about two years ago, for example, and there are related
complaints in the Tcl bug tracker. I had discussed a fix of this kind
off-list with Henry Spencer, but didn't get around to doing something
about it until the issue was rediscovered by Greg Stark recently.
Back-patch to all supported branches.
Some of the functions in regex compilation and execution recurse, and
therefore could in principle be driven to stack overflow. The Tcl crew
has seen this happen in practice in duptraverse(), though their fix was
to put in a hard-wired limit on the number of recursive levels, which is
not too appetizing --- fortunately, we have enough infrastructure to check
the actually available stack. Greg Stark has also seen it in other places
while fuzz testing on a machine with limited stack space. Let's put guards
in to prevent crashes in all these places.
Since the regex code would leak memory if we simply threw elog(ERROR),
we have to introduce an API that checks for stack depth without throwing
such an error. Fortunately that's not difficult.
Commit 9662143f0c added infrastructure to
allow regular-expression operations to be terminated early in the event
of SIGINT etc. However, fuzz testing by Greg Stark disclosed that there
are still cases where regex compilation could run for a long time without
noticing a cancel request. Specifically, the fixempties() phase never
adds new states, only new arcs, so it doesn't hit the cancel check I'd put
in newstate(). Add one to newarc() as well to cover that.
Some experimentation of my own found that regex execution could also run
for a long time despite a pending cancel. We'd put a high-level cancel
check into cdissect(), but there was none inside the core text-matching
routines longest() and shortest(). Ordinarily those inner loops are very
very fast ... but in the presence of lookahead constraints, not so much.
As a compromise, stick a cancel check into the stateset cache-miss
function, which is enough to guarantee a cancel check at least once per
lookahead constraint test.
Making this work required more attention to error handling throughout the
regex executor. Henry Spencer had apparently originally intended longest()
and shortest() to be incapable of incurring errors while running, so
neither they nor their subroutines had well-defined error reporting
behaviors. However, that was already broken by the lookahead constraint
feature, since lacon() can surely suffer an out-of-memory failure ---
which, in the code as it stood, might never be reported to the user at all,
but just silently be treated as a non-match of the lookahead constraint.
Normalize all that by inserting explicit error tests as needed. I took the
opportunity to add some more comments to the code, too.
Back-patch to all supported branches, like the previous patch.
newnfa() failed to set the regex error state when malloc() fails.
Several places in regcomp.c failed to check for an error after calling
subre(). Each of these mistakes could lead to null-pointer-dereference
crashes in memory-starved backends.
Report and patch by Andreas Seltenreich. Back-patch to all branches.
The regex code didn't have any provision for query cancel; which is
unsurprising given its non-Postgres origin, but still problematic since
some operations can take a long time. Introduce a callback function to
check for a pending query cancel or session termination request, and
call it in a couple of strategic spots where we can make the regex code
exit with an error indicator.
If we ever actually split out the regex code as a standalone library,
some additional work will be needed to let the cancel callback function
be specified externally to the library. But that's straightforward
(certainly so by comparison to putting the locale-dependent character
classification logic on a similar arms-length basis), and there seems
no need to do it right now.
A bigger issue is that there may be more places than these two where
we need to check for cancels. We can always add more checks later,
now that the infrastructure is in place.
Since there are known examples of not-terribly-long regexes that can
lock up a backend for a long time, back-patch to all supported branches.
I have hopes of fixing the known performance problems later, but adding
query cancel ability seems like a good idea even if they were all fixed.
The previous coding of this function could get into situations where it
would never terminate, because successive passes would re-add EMPTY arcs
that had been removed by the previous pass. Rewrite the function
completely using a new algorithm that is guaranteed to terminate, and
also seems to be usually faster than the old one. Per Tcl bugs 3604074
and 3606683.
Tom Lane and Don Porter
The previous coding abused the first element of a cNFA state's arcs list
to hold a per-state flag bit, which was confusing, undocumented, and not
even particularly efficient. Get rid of that in favor of a separate
"stflags" vector. Since there's only one bit in use, I chose to allocate a
char per state; we could possibly replace this with a bitmap at some point,
but that would make accesses a little slower. It's already about 8X
smaller than before, so let's not get overly tense.
Also document the representation better than it was before, which is to say
not at all.
This patch is a byproduct of investigations towards extracting a "fixed
prefix" string from the compact-NFA representation of regex patterns.
Might need to back-patch it if we decide to back-patch that fix, but for
now it's just code cleanup so I'll just put it in HEAD.
was Tcl 8.4.8. The main changes are to remove the never-fully-implemented
code for multi-character collating elements, and to const-ify some stuff a
bit more fully. In combination with the recent security patch, this commit
brings us into line with Tcl 8.5.0.
Note that I didn't make any effort to duplicate a lot of cosmetic changes
that they made to bring their copy into line with their own style
guidelines, such as adding braces around single-line IF bodies. Most of
those we either had done already (such as ANSI-fication of function headers)
or there is no point because pgindent would undo the change anyway.
are shared with Tcl, since it's their code to begin with, and the patches
have been copied from Tcl 8.5.0. Problems:
CVE-2007-4769: Inadequate check on the range of backref numbers allows
crash due to out-of-bounds read.
CVE-2007-4772: Infinite loop in regex optimizer for pattern '($|^)*'.
CVE-2007-6067: Very slow optimizer cleanup for regex with a large NFA
representation, as well as crash if we encounter an out-of-memory condition
during NFA construction.
Part of the response to CVE-2007-6067 is to put a limit on the number of
states in the NFA representation of a regex. This seems needed even though
the within-the-code problems have been corrected, since otherwise the code
could try to use very large amounts of memory for a suitably-crafted regex,
leading to potential DOS by driving the system into swap, activating a kernel
OOM killer, etc.
Although there are certainly plenty of ways to drive the system into effective
DOS with poorly-written SQL queries, these problems seem worth treating as
security issues because many applications might accept regex search patterns
from untrustworthy sources.
Thanks to Will Drewry of Google for reporting these problems. Patches by Will
Drewry and Tom Lane.
Security: CVE-2007-4769, CVE-2007-4772, CVE-2007-6067
(extracted from Tcl 8.4.1 release, as Henry still hasn't got round to
making it a separate library). This solves a performance problem for
multibyte, as well as upgrading our regexp support to match recent Tcl
and nearly match recent Perl.
Tom Lane
Bruce Momjian
Magnus Hagander
PostgreSQL Daemon