The previous comment described how things worked in PostgreSQL 8.2
and prior.

Thom Brown

cost_index's method for estimating per-tuple costs of evaluating filter
conditions (a/k/a qpquals) was completely wrong in the presence of derived
indexable conditions, such as range conditions derived from a LIKE clause.
This was largely masked in common cases as a result of all simple operator
clauses having about the same costs, but it could show up in a big way when
dealing with functional indexes containing expensive functions, as seen for
example in bug #6579 from Istvan Endredy.  Rejigger the calculation to give
sane answers when the indexquals aren't a subset of the baserestrictinfo
list.  As a side benefit, we now do the calculation properly for cases
involving join clauses (ie, parameterized indexscans), which we always
overestimated before.

There are still cases where this is an oversimplification, such as clauses
that can be dropped because they are implied by a partial index's
predicate.  But we've never accounted for that in cost estimates before,
and I'm not convinced it's worth the cycles to try to do so.

Previously we attempted to throw an error or at least warning for missing
schemas, but this was done inconsistently because of implementation
restrictions (in many cases, GUC settings are applied outside transactions
so that we can't do system catalog lookups).  Furthermore, there were
exceptions to the rule even in the beginning, and we'd been poking more
and more holes in it as time went on, because it turns out that there are
lots of use-cases for having some irrelevant items in a common search_path
value.  It seems better to just adopt a philosophy similar to what's always
been done with Unix PATH settings, wherein nonexistent or unreadable
directories are silently ignored.

This commit also fixes the documentation to point out that schemas for
which the user lacks USAGE privilege are silently ignored.  That's always
been true but was previously not documented.

This is mostly in response to Robert Haas' complaint that 9.1 started to
throw errors or warnings for missing schemas in cases where prior releases
had not.  We won't adopt such a significant behavioral change in a back
branch, so something different will be needed in 9.1.

postgres:// URIs are an attempt to "stop the bleeding" in this general
area that has been said to occur due to external projects adopting their
own syntaxes.  The syntaxes supported by this patch:

 postgres://[user[:pwd]@][unix-socket][:port[/dbname]][?param1=value1&...]
 postgres://[user[:pwd]@][net-location][:port][/dbname][?param1=value1&...]

should be enough to cover most interesting cases without having to
resort to "param=value" pairs, but those are provided for the cases that
need them regardless.

libpq documentation has been shuffled around a bit, to avoid stuffing
all the format details into the PQconnectdbParams description, which was
already a bit overwhelming.  The list of keywords has moved to its own
subsection, and the details on the URI format live in another subsection.

This includes a simple test program, as requested in discussion, to
ensure that interesting corner cases continue to work appropriately in
the future.

Author: Alexander Shulgin
Some tweaking by Álvaro Herrera, Greg Smith, Daniel Farina, Peter Eisentraut
Reviewed by Robert Haas, Alexey Klyukin (offlist), Heikki Linnakangas,
Marko Kreen, and others

Oh, it also supports postgresql:// but that's probably just an accident.

This definition is convenient when applying the function to the
reltablespace column of pg_class, since that's what zero means there;
and it doesn't interfere with any other plausible use of the function.
Per gripe from Bruce Momjian.

default tablespace, but part of a database that is in a user-defined
tablespace.  Caused "file not found" error during upgrade.

Per bug report from Ants Aasma.

Backpatch to 9.1 and 9.0.

Since xgettext provides options to do this now, we might as well use
them.

Only match when WITH is the first word, as WITH may appear in many
other contexts.

Josh Kupershmidt

This patch reverts commit 191ef2b4
and thereby restores the pre-7.3 behavior of EXTRACT(EPOCH FROM
timestamp-without-tz).  Per discussion, the more recent behavior was
misguided on a couple of grounds: it makes it hard to get a
non-timezone-aware epoch value for a timestamp, and it makes this one
case dependent on the value of the timezone GUC, which is incompatible
with having timestamp_part() labeled as immutable.

The other behavior is still available (in all releases) by explicitly
casting the timestamp to timestamp with time zone before applying EXTRACT.

This will need to be called out as an incompatible change in the 9.2
release notes.  Although having mutable behavior in a function marked
immutable is clearly a bug, we're not going to back-patch such a change.

It used to point to a top-level page that contains client-side tools as
well. It was hard to find the procedural language there.

Thom Brown

It's still non-deterministic in some sense ... but given fixed settings
and identical planning problems, it will now always choose the same plan,
so we probably shouldn't tar it with that brush.  Per bug #6565 from
Guillaume Cottenceau.  Back-patch to 9.0 where the behavior was fixed.

storage.

because there was only a beta for 9.0 and it does not compile on 9.1.

estimate_num_groups() gets unhappy with
	create table empty();
	select * from empty except select * from empty e2;
I can't see any actual use-case for such a query (and the table is illegal
per SQL spec), but it seems like a good idea that it not cause an assert
failure.

The case could not arise when this code was originally written, but it can
now (since we made zero-column MergeJoins work for the benefit of FULL JOIN
ON TRUE).  I don't think there is any actual bug here, but we might as well
treat it consistently with other uses of COPY_POINTER_FIELD().  Per comment
from Ashutosh Bapat.

There's no need to sit there and increment the stats when we know all the
increments would be zero anyway.  The actual additions might not be very
expensive, but skipping acquisition of the spinlock seems like a good
thing.  Pushing the logic about initialization of the usage count down into
entry_alloc() allows us to do that while making the code actually simpler,
not more complex.  Expansion on a suggestion by Peter Geoghegan.

Thom Browne pointed out that the URL was out of date, and Devrim GÜNDÜZ
pointed out that the project isn't maintained anymore.

Patch by me; review by Tom Lane and others.

This patch addresses a deficiency in the previous pg_stat_statements patch.
We want to give sticky entries an initial "usage" factor high enough that
they probably will stick around until their query is completed.  However,
if the query never completes (eg it gets an error during execution), the
entry shouldn't persist indefinitely.  Manage this by starting out with
a usage setting equal to the (approximate) median usage value within the
whole hashtable, but decaying the value much more aggressively than we
do for normal entries.

Peter Geoghegan

This was a thinko in previous commit. Now that stack base pointer is now set
in PostmasterMain and SubPostmasterMain, it doesn't need to be set in
PostgresMain anymore.

We used to only initialize the stack base pointer when starting up a regular
backend, not in other processes. In particular, autovacuum workers can run
arbitrary user code, and without stack-depth checking, infinite recursion
in e.g an index expression will bring down the whole cluster.

The comment about PL/Java using set_stack_base() is not yet true. As the
code stands, PL/java still modifies the stack_base_ptr variable directly.
However, it's been discussed in the PL/Java mailing list that it should be
changed to use the function, because PL/Java is currently oblivious to the
register stack used on Itanium. There's another issues with PL/Java, namely
that the stack base pointer it sets is not really the base of the stack, it
could be something close to the bottom of the stack. That's a separate issue
that might need some further changes to this code, but that's a different
story.

Backpatch to all supported releases.

Thom Brown

XLOG_GIN_UPDATE_META_PAGE and XLOG_GIN_DELETE_LISTPAGE records were printed
with a list link field labeled as "blkno", which was confusing, especially
when the link was empty (InvalidBlockNumber).  Print the metapage block
number instead, since that's what's actually being updated.  We could
include the link values too as a separate field, but not clear it's worth
the trouble.

Back-patch to 8.4 where the dubious code was added.

Commit 337b6f5e contained the entirely
fanciful assumption that it had made comparetup_datum unreachable.
Reported and patched by Takashi Yamamoto.

Fix up some not terribly accurate/useful comments from that commit, too.

Thom Brown

Thom Brown

If we make the initially-called function return the table physical-size
estimate, acquire_inherited_sample_rows will be able to use that to
allocate numbers of samples among child tables, when the day comes that
we want to support foreign tables in inheritance trees.

ANALYZE now accepts foreign tables and allows the table's FDW to control
how the sample rows are collected.  (But only manual ANALYZEs will touch
foreign tables, for the moment, since among other things it's not very
clear how to handle remote permissions checks in an auto-analyze.)

contrib/file_fdw is extended to support this.

Etsuro Fujita, reviewed by Shigeru Hanada, some further tweaking by me.

Report by Guillaume Lelarge.

Report by Andrew Dunstan.

The option --no-wrap prevents wars with (most?) editors about proper
line wrapping.  --sort-by-file ensures consistent file order, for
easier diffing.

Greg Smith and Jaime Casanova, reviewed by Alex Shulgin and myself.
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