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
Foreign tables are a core component of SQL/MED. This commit does
not provide a working SQL/MED infrastructure, because foreign tables
cannot yet be queried. Support for foreign table scans will need to
be added in a future patch. However, this patch creates the necessary
system catalog structure, syntax support, and support for ancillary
operations such as COMMENT and SECURITY LABEL.
Shigeru Hanada, heavily revised by Robert Haas
The contents of an unlogged table are WAL-logged; thus, they are not
available on standby servers and are truncated whenever the database
system enters recovery. Indexes on unlogged tables are also unlogged.
Unlogged GiST indexes are not currently supported.
This is intended as infrastructure to support integration with label-based
mandatory access control systems such as SE-Linux. Further changes (mostly
hooks) will be needed, but this is a big chunk of it.
KaiGai Kohei and Robert Haas
I've added a quote_all_identifiers GUC which affects the behavior
of the backend, and a --quote-all-identifiers argument to pg_dump
and pg_dumpall which sets the GUC and also affects the quoting done
internally by those applications.
Design by Tom Lane; review by Alex Hunsaker; in response to bug #5488
filed by Hartmut Goebel.
is still available, but you must now write the long equivalent --inserts
or --column-inserts. This change is made to eliminate confusion with the
use of -d to specify a database name in most other Postgres client programs.
Original patch by Greg Mullane, modified per subsequent discussion.
performing dumps and restores in accordance with a security policy that
forbids logging in directly as superuser, but instead specifies that you
should log into an admin account and then SET ROLE to the superuser.
In passing, clean up some ugly and mostly-broken code for quoting shell
arguments in pg_dumpall.
Benedek László, with some help from Tom Lane
the server version check is now always enforced. Relax the version check to
allow a server that is of pg_dump's own major version but a later minor
version; this is the only case that -i was at all safe to use in.
pg_restore already enforced only a very weak version check, so this is
really just a documentation change for it.
Per discussion.
dumps can be loaded into databases without the same tablespaces that the
source had. The option acts by suppressing all "SET default_tablespace"
commands, and also CREATE TABLESPACE commands in pg_dumpall's case.
Gavin Roy, with documentation and minor fixes by me.
Standard English uses "may", "can", and "might" in different ways:
may - permission, "You may borrow my rake."
can - ability, "I can lift that log."
might - possibility, "It might rain today."
Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice. Similarly, "It may crash" is better stated, "It might crash".
to process all inclusion switches then all exclusion switches, so that the
behavior is independent of switch ordering.
Use of -T does not cause non-table objects to be suppressed. And
the patterns are now interpreted the same way psql's \d commands do it,
rather than as pure regex commands; this allows for example -t schema.tab
to do what it should have been doing all along. Re-enable the --blobs
switch to do something useful, ie, add back blobs into a dump they were
otherwise suppressed from.
portable long options. But we have had portable long options for a long
time now, so this is obsolete. Now people have added options which *only*
work with -X but not as regular long option, so I'm putting a stop to this:
-X is deprecated; it still works, but it has been removed from the
documentation, and please don't add more of them.
The Problem: Occassionally a DBA needs to dump a database to a new
encoding. In instances where the current encoding, (or lack of an
encoding, like SQL_ASCII) is poorly supported on the target database
server, it can be useful to dump into a particular encoding. But,
currently the only way to set the encoding of a pg_dump file is to
change client_encoding in postgresql.conf and restart postmaster.
This is more than a little awkward for production systems.
Magnus Hagander
using the recently added lo_create() function. The restore logic in
pg_restore is greatly simplified as well, since there's no need anymore
to try to adjust database references to match a new set of blob OIDs.
AUTHORIZATION commands by default. Move all GRANT and REVOKE commands
to the end of the dump to avoid restore failures in several situations.
Bring back --use-set-session-authorization option to get previous SET
behaviour
Christopher Kings-Lyne
proposal for eventually deprecating OIDs on user tables that I posted
earlier to pgsql-hackers. pg_dump now always specifies WITH OIDS or
WITHOUT OIDS when dumping a table. The documentation has been updated.
Neil Conway
to control object ownership. The use-set-session-authorization and
no-reconnect switches are obsolete (still accepted on the command line,
but they don't do anything). This is a precursor to fixing handling
of CREATE SCHEMA, which will be a separate commit.
not all SQL identifiers taken from command line arguments. We decided
years ago that that was a bad idea: identifiers taken from the command
line should be treated as literally correct. Remove the inconsistent
code that has crept in recently. Also fix pg_dump so that the combination
of --schema and --table does what you'd expect, namely dump exactly one
table from exactly one schema. Per gripe from Deepak Bhole of Red Hat.
> I don't care what you use for short options if all useful ones are taken.
> But the long option should be --schema.
Ok, fair enough: a revised patch is attached that uses the '-n' short
option and the '--schema' long option.
Neil Conway
including:
- replacing all the appropriate usages of <citetitle>PostgreSQL
...</citetitle> with &cite-user;, &cite-admin;, and so on
- fix an omission in the EXECUTE documentation
- add some more text to the EXPLAIN documentation
- improve the PL/PgSQL RETURN NEXT documentation (more work to do here)
- minor markup fixes
Neil Conway
The -n and -N options were removed. Quoting is now smart enough to
supply quotes if and only if necessary.
Numerical types are now printed without quotes, except in cases of
special values such as NaN.
Boolean values printed as true and false.
Most string literals now do not escape whitespace characters (newlines,
etc.) for portability.
SET SESSION AUTHORIZATION argument is a string literal, to follow SQL.
Made commands output by pg_dump use consistent spacing and indentation.
capabilities of specifying time zones as intervals per SQL9x.
Put refentrytitle contents on the same line as the tag.
Otherwise, leading whitespace is propagated into the product, which
(at least) messes up the ToC layout.
Remove (some) docinfo tags containing dates. Best to omit if the dates
are not accurate; maybe use CVS dates instead or leave them out.
Don't hardcode the maximum accepted server version, use PG_VERSION instead.
Install a notice processor so notices are handled like error messages.
Word smithing.
not all of them attached properly in the post I made a few minutes
ago. Please disregard those earlier files. The diffs in the tar file
replace them.
Pierce Tyler
Heikki Linnakangas
Bruce Momjian
Robert Haas
Peter Eisentraut
Magnus Hagander
Tom Lane
Alvaro Herrera
Neil Conway
PostgreSQL Daemon
Thomas G. Lockhart
Philip Warner