This provides a separate exception class for each error code that the
backend defines, as well as the ability to get the SQLSTATE from the
exception object.
Jan Urbański, reviewed by Steve Singer
Until now, our Serializable mode has in fact been what's called Snapshot
Isolation, which allows some anomalies that could not occur in any
serialized ordering of the transactions. This patch fixes that using a
method called Serializable Snapshot Isolation, based on research papers by
Michael J. Cahill (see README-SSI for full references). In Serializable
Snapshot Isolation, transactions run like they do in Snapshot Isolation,
but a predicate lock manager observes the reads and writes performed and
aborts transactions if it detects that an anomaly might occur. This method
produces some false positives, ie. it sometimes aborts transactions even
though there is no anomaly.
To track reads we implement predicate locking, see storage/lmgr/predicate.c.
Whenever a tuple is read, a predicate lock is acquired on the tuple. Shared
memory is finite, so when a transaction takes many tuple-level locks on a
page, the locks are promoted to a single page-level lock, and further to a
single relation level lock if necessary. To lock key values with no matching
tuple, a sequential scan always takes a relation-level lock, and an index
scan acquires a page-level lock that covers the search key, whether or not
there are any matching keys at the moment.
A predicate lock doesn't conflict with any regular locks or with another
predicate locks in the normal sense. They're only used by the predicate lock
manager to detect the danger of anomalies. Only serializable transactions
participate in predicate locking, so there should be no extra overhead for
for other transactions.
Predicate locks can't be released at commit, but must be remembered until
all the transactions that overlapped with it have completed. That means that
we need to remember an unbounded amount of predicate locks, so we apply a
lossy but conservative method of tracking locks for committed transactions.
If we run short of shared memory, we overflow to a new "pg_serial" SLRU
pool.
We don't currently allow Serializable transactions in Hot Standby mode.
That would be hard, because even read-only transactions can cause anomalies
that wouldn't otherwise occur.
Serializable isolation mode now means the new fully serializable level.
Repeatable Read gives you the old Snapshot Isolation level that we have
always had.
Kevin Grittner and Dan Ports, reviewed by Jeff Davis, Heikki Linnakangas and
Anssi Kääriäinen
This fixes make distprep, and seems more robust in other ways as well.
Some special handling is required because errcodes.txt is needed by
some stuff in src/port, but just by src/backend as is the case for the
other generated headers.
While I'm at it, fix a few other things that were overlooked in the
original patch.
src/pl/plpgsql/src/plerrcodes.h, src/include/utils/errcodes.h, and a
big chunk of errcodes.sgml are now automatically generated from a single
file, src/backend/utils/errcodes.txt.
Jan Urbański, reviewed by Tom Lane.
This tool makes it possible to do the pg_start_backup/
copy files/pg_stop_backup step in a single command.
There are still some steps to be done before this is a
complete backup solution, such as the ability to stream
the required WAL logs, but it's still usable, and
could do with some buildfarm coverage.
In passing, make the checkpoint request optionally
fast instead of hardcoding it.
Magnus Hagander, reviewed by Fujii Masao and Dimitri Fontaine
Makes it easier to parse mainly the BASE_BACKUP command
with it's options, and avoids having to manually deal
with quoted identifiers in the label (previously broken),
and makes it easier to add new commands and options in
the future.
In passing, refactor the case statement in the walsender
to put each command in it's own function.
This is slower than the original coding but avoids the problem of
including files in an unpredictable order. Aside from being more
trustworthy, we can get rid of some exclusions that were formerly
made for what turn out to be ordering or re-inclusion problems.
I also modified it to include libpq's exported files in the check.
ecpg should be included as well, but I'm unclear on which ecpg .h
files are meant to be included by clients.
Replace for loops in makefiles with proper dependencies. Parallel
make can now span across directories. Also, make -k and make -q work
properly.
GNU make 3.80 or newer is now required.
Look only at the non-localized part of the output from "vcbuild /?",
which is used to determine the version of Visual Studio in use. Different
languages seem to localize different amounts of the string, but we assume
the part "Microsoft Visual C++" won't be modified.
1. Resurrect the behavior where old commits on master will have Branch:
labels for branches sprouted after the commit was made. I'm still
dubious about this mode, but if you want it, say --post-date or -p.
2. Annotate the Branch: labels with the release or branch in which the
commit was publicly released. For example, on a release branch you could
see
Branch: REL8_3_STABLE Release: REL8_3_2 [92c3a8004] 2008-03-29 00:15:37 +0000
showing that the fix was released in 8.3.2. Commits on master will
usually instead have notes like
Branch: master Release: REL8_4_BR [6fc9d4272] 2008-03-29 00:15:28 +0000
showing that this commit is ancestral to release branches 8.4 and later.
If no Release: marker appears, the commit hasn't yet made it into any
release.
3. Add support for release branches older than 7.4.
4. The implementation is improved by running git log on each branch only
back to where the branch sprouts from master. This saves a good deal
of time (about 50% of the runtime when generating the complete history).
We generate the post-date-mode tags via a direct understanding that
they should be applied to master commits made before the branch sprouted,
rather than backing into them via matching (which isn't any too
reliable when people used identical log messages for successive commits).
1. Don't assume there's only one candidate match; check them all and use the
one with the closest timestamp. Avoids funny output when someone makes
several successive commits with the same log message, as certain people
have been known to do.
2. When the same commit (with the same SHA1) is reachable from multiple
branch tips, don't report it for all the branches; instead report it only
for the first such branch. Given our development practices, this case
arises only for commits that occurred before a given branch split off from
master. The original coding blamed old commits on *all* the branches,
which isn't terribly useful; the new coding blames such a commit only on
master.
1. Don't forget the last (oldest) commit on the oldest branch.
2. When considering which commit to print next, if two alternatives have
the same "distortion" score (which is actually the normal case, since
generally the "distortion" is 0), then choose the later timestamp to
print first. I don't know where Robert got the idea to ignore timestamps
and sort by branch age, but it wasn't a good idea: the resulting ordering
of commits was just plain bizarre anywhere that some branches had many
fewer commits than others, which is the typical situation for us.
Avoid depending on Date::Calc, which isn't in a basic Perl installation,
when we can equally well use Time::Local which is. Also fix the parsing
of timestamps to take heed of the timezone. (It looks like cvs2git emitted
all commit timestamps with zone GMT, so this refinement might've looked
unnecessary when looking at converted data; but it's needed now.)
Fix parsing of message bodies so that blank lines that may or may not get
emitted by "git log" aren't confused with real data. This avoids strange
formatting of the oldest commit on a branch.
Check child-process exit status, so that we actually notice if "git log"
fails, and so that we don't accumulate zombie children.
