There was a race condition where the receiving pipe could be closed by the
child thread if the main thread was pre-empted before it got a chance to
create a new one, and the dispatch thread ran to completion during that time.
One symptom of this is that rows in pg_listener could be dropped under
heavy load.
Analysis and original patch by Radu Ilie, with some small
modifications by Magnus Hagander.
Since all current and foreseeable future command tags will be pure ASCII,
there is no need to do conversion on them. This saves a few cycles and also
avoids polluting otherwise-pristine subtransaction memory contexts, which
is the cause of the backend memory leak exhibited in bug #5302. (Someday
we'll probably want to have a better method of determining whether
subtransaction contexts need to be kept around, but today is not that day.)
Backpatch to 8.0. The cycle-shaving aspect of this would work in 7.4
too, but without subtransactions the memory-leak aspect doesn't apply,
so it doesn't seem worth touching 7.4.
(failure to free col_lineptrs[] array elements) and exacerbated in the
current devel cycle (failure to free "wrap"). This resulted in moderate
bloat of psql over long script runs. Noted while testing bug #5302,
although what the reporter was complaining of was backend-side leakage.
false positives during Hot Standby conflict processing. Simple
patch to enhance conflict processing, following previous discussions.
Controlled by parameter minimize_standby_conflicts = on | off, with
default off allows measurement of performance impact to see whether
it should be set on all the time.
records for heap and btree. Minor change, mostly API changes to
pass through the required values. This is a simple change though
also provides the refactoring required for further enhancements
to conflict processing using the relOid. Changes only have effect
during Hot Standby.
PQconnectStartParams. These are analogous to PQconnectdb and PQconnectStart
respectively. They differ from the legacy functions in that they accept
two NULL-terminated arrays, keywords and values, rather than conninfo
strings. This avoids the need to build the conninfo string in cases
where it might be inconvenient to do so. Includes documentation.
Also modify psql to utilize PQconnectdbParams rather than PQsetdbLogin.
This allows the new config parameter application_name to be set, which
in turn is displayed in the pg_stat_activity view and included in CSV
log entries. This will also ensure both new functions get regularly
exercised.
Patch by Guillaume Lelarge with review and minor adjustments by
Joe Conway.
LogwrtRqst.Write can be set to non-existent FF log segment, we mustn't
try to send that in XLogSend().
Also fix similar bug in ReadRecord(), which I just introduced in the
ReadRecord() refactoring patch.
restore_command, if the connection to the primary server is lost. This
ensures that the standby can recover automatically, if the connection is
lost for a long time and standby falls behind so much that the required
WAL segments have been archived and deleted in the master.
This also makes standby_mode useful without streaming replication; the
server will keep retrying restore_command every few seconds until the
trigger file is found. That's the same basic functionality pg_standby
offers, but without the bells and whistles.
To implement that, refactor the ReadRecord/FetchRecord functions. The
FetchRecord() function introduced in the original streaming replication
patch is removed, and all the retry logic is now in a new function called
XLogReadPage(). XLogReadPage() is now responsible for executing
restore_command, launching walreceiver, and waiting for new WAL to arrive
from primary, as required.
This also changes the life cycle of walreceiver. When launched, it now only
tries to connect to the master once, and exits if the connection fails, or
is lost during streaming for any reason. The startup process detects the
death, and re-launches walreceiver if necessary.
- Allow (ineffective) use of 'require' in plperl
If the required module is not already loaded then it dies.
So "use strict;" now works in plperl.
- Pre-load the feature module if perl >= 5.10.
So "use feature :5.10;" now works in plperl.
- Stored procedure subs are now given names.
The names are not visible in ordinary use, but they make
tools like Devel::NYTProf and Devel::Cover much more useful.
- Simplified and generalized the subroutine creation code.
Now one code path for generating sub source code, not four.
Can generate multiple 'use' statements with specific imports
(which handles plperl.use_strict currently and can easily
be extended to handle a plperl.use_feature=':5.12' in future).
- Disallows use of Safe version 2.20 which is broken for PL/Perl.
http://rt.perl.org/rt3/Ticket/Display.html?id=72068
- Assorted minor optimizations by pre-growing data structures.
Patch from Tim Bunce, reviewed by Alex Hunsaker.
default of "plpgsql". This is more reasonable than it was when the DO patch
was written, because we have since decided that plpgsql should be installed
by default. Per discussion, having a parameter for this doesn't seem useful
enough to justify the risk of application breakage if the value is changed
unexpectedly.
These files have apparently been edited over the years by a dozen people
with as many different editor settings, which made the alignment of the
paragraphs quite inconsistent and ugly. I made a pass of M-q with Emacs
to straighten it out.
and implement OVERLAY() for bit strings and bytea.
In passing also convert text OVERLAY() to a true built-in, instead of
relying on a SQL function.
Leonardo F, reviewed by Kevin Grittner
You might think this is unnecessary since that interpreter is never used
to run code --- but it turns out that's wrong. As of Tcl 8.5, the "clock"
command (alone among builtin Tcl commands) is partially implemented by
loaded-on-demand Tcl code, which means that it fails if there's not
unknown-command support, and also that it's impossible to run it directly
in a safe interpreter. The way they get around the latter is that
Tcl_CreateSlave() automatically sets up an alias command that forwards any
execution of "clock" in a safe slave interpreter to its parent interpreter.
Thus, when attempting to execute "clock" in trusted pltcl, the command
actually executes in the "hold" interpreter, where it will fail if
unknown-command support hasn't been introduced by sourcing the standard
init.tcl script, which is done by Tcl_Init(). (This is a pretty dubious
design decision on the Tcl boys' part, if you ask me ... but they didn't.)
Back-patch all the way. It's not clear that anyone would try to use ancient
versions of pltcl with a recent Tcl, but it's not clear they wouldn't, either.
Also add a regression test using "clock", in branches that have regression
test support for pltcl.
Per recent trouble report from Kyle Bateman.
AbortTransaction or AbortSubTransaction, when trying to clean up after an
error that prevented (sub)transaction start from completing:
* access to TopTransactionResourceOwner that might not exist
* assert failure in AtEOXact_GUC, if AtStart_GUC not called yet
* assert failure or core dump in AfterTriggerEndSubXact, if
AfterTriggerBeginSubXact not called yet
Per testing by injecting elog(ERROR) at successive steps in StartTransaction
and StartSubTransaction. It's not clear whether all of these cases could
really occur in the field, but at least one of them is easily exposed by
simple stress testing, as per my accidental discovery yesterday.
the various disk-size-reporting functions will respond to query cancel
reasonably promptly even in very large databases. Per report from
Kevin Grittner.
woken by alarm we send SIGUSR1 to all backends requesting that they
check to see if they are blocking Startup process. If so, they throw
ERROR/FATAL as for other conflict resolutions. Deadlock stop gap
removed. max_standby_delay = -1 option removed to prevent deadlock.
Attributes can now have options, just as relations and tablespaces do, and
the reloptions code is used to parse, validate, and store them. For
simplicity and because these options are not performance critical, we store
them in a separate cache rather than the main relcache.
Thanks to Alex Hunsaker for the review.
PQescapeLiteral is similar to PQescapeStringConn, but it relieves the
caller of the need to know how large the output buffer should be, and
it provides the appropriate quoting (in addition to escaping special
characers within the string). PQescapeIdentifier provides similar
functionality for escaping identifiers.
Per recent discussion with Tom Lane.
Magnus Hagander
Tom Lane
Andrew Dunstan
Simon Riggs
Robert Haas
Michael Meskes
Itagaki Takahiro
Peter Eisentraut
Heikki Linnakangas
Joe Conway