> A third idea would be for a heap scan to check if all rows are visible
> and if so set a per-table flag which can be checked by index scans.
> Any change to the table would have to clear the flag. To detect
> changes during the heap scan a counter could be set at the start and
> checked at the end --- if it is the same, the table has not been
> modified --- any table change would increment the counter.
certain corner cases. Per discussion, the code does what we want, but
it really needs to be documented that these functions act differently
from regexp_matches.
that cached compiled patterns will still be there when the function is next
called. Clean up looping logic, thereby fixing bug identified by Pavel
Stehule. Share setup code between the two functions, add some comments, and
avoid risky mixing of int and size_t variables. Clean up the documentation a
tad, and accept all the flag characters mentioned in table 9-19 rather than
just a subset.
displayed in the postmaster log. This avoids Windows-specific problems with
localized time zone names that are in the wrong encoding, and generally seems
like a good idea to forestall other potential platform-dependent issues.
To preserve the existing behavior that all backends will log in the same time
zone, create a new GUC variable log_timezone that can only be changed on a
system-wide basis, and reference log-related calculations to that zone instead
of the TimeZone variable.
This fixes the issue reported by Hiroshi Saito that timestamps printed by
xlog.c startup could be improperly localized on Windows. We still need a
simpler patch for that problem in the back branches, however.
so that we will be able to create a cookie for all processes for CSVlogs.
It is set wherever MyProcPid is set. Take the opportunity to remove the now
unnecessary session-only restriction on the %s and %c escapes in log_line_prefix.
before reporting a transaction committed. Data consistency is still
guaranteed (unlike setting fsync = off), but a crash may lose the effects
of the last few transactions. Patch by Simon, some editorialization by Tom.
sugar for PL/PgSQL set-returning functions that want to return the result
of evaluating a query; it should also be more efficient than repeated
RETURN NEXT statements. Based on an earlier patch from Pavel Stehule.
and fsync WAL at convenient intervals. For the moment it just tries to
offload this work from backends, but soon it will be responsible for
guaranteeing a maximum delay before asynchronously-committed transactions
will be flushed to disk.
This is a portion of Simon Riggs' async-commit patch, committed to CVS
separately because a background WAL writer seems like it might be a good idea
independently of the async-commit feature. I rebased walwriter.c on
bgwriter.c because it seemed like a more appropriate way of handling signals;
while the startup/shutdown logic in postmaster.c is more like autovac because
we want walwriter to quit before we start the shutdown checkpoint.
I/O utilization, per discussion.
While at it, lower the autovacuum vacuum and analyze threshold values to 50
tuples. It is a bit higher (i.e. more conservative) than what I originally
proposed but much better than the old values for small tables.
against a Unix server, and Windows-specific server-side authentication
using SSPI "negotiate" method (Kerberos or NTLM).
Only builds properly with MSVC for now.
name. With this patch, it is always possible for the user to qualify a
plpgsql variable name if needed to avoid ambiguity. While there is much more
work to be done in this area, this simple change removes one unnecessary
incompatibility with Oracle. Per discussion.
of variable substitution and plan caching behavior in dedicated sections.
(A lot of this material existed already, but was scattered in various places
in the chapter.) Reorganize material a little bit, mostly to try to avoid
diving into deep details in the first introductory sections. Document some
fine points that had escaped treatment before, notably the ability to qualify
plpgsql variable names with block labels. Some minor wordsmithing here and
there.
literally, whether quoted or not. Since we allow $ as a character within
identifiers, this behavior is useful, whereas the previous behavior of
treating it as the regexp ending anchor was nearly useless given that the
pattern is automatically anchored anyway. This affects the arguments of
psql's \d commands as well as pg_dump's -n and -t switches. Per discussion.
PGconn. Invent a new libpq connection-status function,
PQconnectionUsedPassword() that returns true if the server
demanded a password during authentication, false otherwise.
This may be useful to clients in general, but is immediately
useful to help plug a privilege escalation path in dblink.
Per list discussion and design proposed by Tom Lane.
Sequences and views could previously be renamed using ALTER TABLE, but
this was a repeated source of confusion for users. Update the docs,
and psql tab completion. Patch from David Fetter; various minor fixes
by myself.
over a fairly long period of time, rather than being spat out in a burst.
This happens only for background checkpoints carried out by the bgwriter;
other cases, such as a shutdown checkpoint, are still done at full speed.
Remove the "all buffers" scan in the bgwriter, and associated stats
infrastructure, since this seems no longer very useful when the checkpoint
itself is properly throttled.
Original patch by Itagaki Takahiro, reworked by Heikki Linnakangas,
and some minor API editorialization by me.
installations whose pg_config program does not appear first in the PATH.
Per gripe from Eddie Stanley and subsequent discussions with Fabien Coelho
and others.
provide visual separation from the rest of the log line; I've been
noticing lately that quite a few newbies fail to figure this out for
themselves. Also a little editorial cleanup of the log_line_prefix
description.
constraints the planner is unable to disprove, hence simple btree-compatible
conditions should be used. We've seen people try to get cute with stuff
like date_part(something) = something at least twice now. Even if we
wanted to try to teach predtest.c about the properties of date_part,
most of the useful variants aren't immutable so nothing could be proved.
within a signal handler (this might be safe given the relatively narrow code
range in which the interrupt is enabled, but it seems awfully risky); do issue
more informative log messages that tell what is being waited for and the exact
length of the wait; minor other code cleanup. Greg Stark and Tom Lane
an array of strings rather than an array of integers, and allow any simple
constant or identifier to be used in typmods; for example
create table foo (f1 widget(42,'23skidoo',point));
Of course the typmodin function has still got to pack this info into a
non-negative int32 for storage, but it's still a useful improvement in
flexibility, especially considering that you can do nearly anything if you
are willing to keep the info in a side table. We can get away with this
change since we have not yet released a version providing user-definable
typmods. Per discussion.
with a plpgsql-defined cursor. The underlying mechanism for this is that the
main SQL engine will now take "WHERE CURRENT OF $n" where $n is a refcursor
parameter. Not sure if we should document that fact or consider it an
implementation detail. Per discussion with Pavel Stehule.
< o Allow UPDATE/DELETE WHERE CURRENT OF cursor
<
< This requires using the row ctid to map cursor rows back to the
< original heap row. This become more complicated if WITH HOLD cursors
< are to be supported because WITH HOLD cursors have a copy of the row
< and no FOR UPDATE lock.
< http://archives.postgresql.org/pgsql-hackers/2007-01/msg01014.php
<
> o -Allow UPDATE/DELETE WHERE CURRENT OF cursor
Along the way, allow FOR UPDATE in non-WITH-HOLD cursors; there may once
have been a reason to disallow that, but it seems to work now, and it's
really rather necessary if you want to select a row via a cursor and then
update it in a concurrent-safe fashion.
Original patch by Arul Shaji, rather heavily editorialized by Tom Lane.
value for the vacuum code. Instead, make zero signify getting the value from a
higher level configuration facility, just like -1 in the original coding. We
still document that -1 is the value that disables the feature, to avoid
confusing the user unnecessarily.
Reported by Galy Lee in <200705310914.l4V9E6JA094603@wwwmaster.postgresql.org>;
per subsequent discussion.
for each temp file, rather than once per sort or hashjoin; this allows
spreading the data of a large sort or join across multiple tablespaces.
(I remain dubious that this will make any difference in practice, but certain
people insisted.) Arrange to cache the results of parsing the GUC variable
instead of recomputing from scratch on every demand, and push usage of the
cache down to the bottommost fd.c level.
were accepted by prior Postgres releases. This takes care of the loose end
left by the preceding patch to downgrade implicit casts-to-text. To avoid
breaking desirable behavior for array concatenation, introduce a new
polymorphic pseudo-type "anynonarray" --- the added concatenation operators
are actually text || anynonarray and anynonarray || text.
from the other string-category types; this eliminates a lot of surprising
interpretations that the parser could formerly make when there was no directly
applicable operator.
Create a general mechanism that supports casts to and from the standard string
types (text,varchar,bpchar) for *every* datatype, by invoking the datatype's
I/O functions. These new casts are assignment-only in the to-string direction,
explicit-only in the other, and therefore should create no surprising behavior.
Remove a bunch of thereby-obsoleted datatype-specific casting functions.
The "general mechanism" is a new expression node type CoerceViaIO that can
actually convert between *any* two datatypes if their external text
representations are compatible. This is more general than needed for the
immediate feature, but might be useful in plpgsql or other places in future.
This commit does nothing about the issue that applying the concatenation
operator || to non-text types will now fail, often with strange error messages
due to misinterpreting the operator as array concatenation. Since it often
(not always) worked before, we should either make it succeed or at least give
a more user-friendly error; but details are still under debate.
Peter Eisentraut and Tom Lane
(Possibly release notes material, lest users be confused.)
The --quiet option is now obsolete and without effect in createdb,
createuser, dropdb, dropuser; kept for compatibility but marked for
removal in 8.4.
Progress messages when acting on all databases now go to stdout instead
of stderr, since they are not in fact errors.
Ordered options in reindexdb reference page alphabetically, like in
other programs' pages.
o -Add a GUC variable to control the tablespace for temporary objects
and sort files
<
< It could start with a random tablespace from a supplied list and
< cycle through the list.
<
tablespace(s) in which to store temp tables and temporary files. This is a
list to allow spreading the load across multiple tablespaces (a random list
element is chosen each time a temp object is to be created). Temp files are
not stored in per-database pgsql_tmp/ directories anymore, but per-tablespace
directories.
Jaime Casanova and Albert Cervera, with review by Bernd Helmle and Tom Lane.
< * Allow free-behind capability for large sequential scans, perhaps using
< posix_fadvise()
> * Allow free-behind capability for large sequential scans to avoid
> kernel cache spoiling
scan-resistant:
<
< * Allow free-behind capability for large sequential scans, perhaps using
< posix_fadvise()
<
< Posix_fadvise() can control both sequential/random file caching and
< free-behind behavior, but it is unclear how the setting affects other
< backends that also have the file open, and the feature is not supported
< on all operating systems.
type. Also, add explicit casts between boolean and text/varchar. Both
of these changes are for conformance with SQL:2003.
Update the regression tests, bump the catversion.
< * Consider allowing 64-bit integers to be passed by value on 64-bit
< platforms
> * Consider allowing 64-bit integers and floats to be passed by value on
> 64-bit platforms
>
> Also change 32-bit floats (float4) to be passed by value at the same
> time.
>
* Improve speed with indexes
For large table adjustments during VACUUM FULL, it is faster to cluster
or reindex rather than update the index. Also, index updates can bloat
the index.
"microsecond" and "millisecond" units were not considered valid input
by themselves, which caused inputs like "1 millisecond" to be rejected
erroneously.
Update the docs, add regression tests, and backport to 8.2 and 8.1
- Function renamed to "xpath".
- Function is now strict, per discussion.
- Return empty array in case when XPath expression detects nothing
(previously, NULL was returned in such case), per discussion.
- (bugfix) Work with fragments with prologue: select xpath('/a',
'<?xml version="1.0"?><a /><b />'); // now XML datum is always wrapped
with dummy <x>...</x>, XML prologue simply goes away (if any).
- Some cleanup.
Nikolay Samokhvalov
Some code cleanup and documentation work by myself.