as methods for implementing the DISTINCT step.  This eliminates the former
performance gap between DISTINCT and GROUP BY, and also makes it possible
to do SELECT DISTINCT on datatypes that only support hashing not sorting.

SELECT DISTINCT ON is still always implemented by sorting; it would take
executor changes to support hashing that, and it's not clear it's worth
the trouble.

This is a release-note-worthy incompatibility from previous PG versions,
since SELECT DISTINCT can no longer be counted on to deliver sorted output
without explicitly saying ORDER BY.  (Anyone who can't cope with that
can consider turning off enable_hashagg.)

Several regression test queries needed to have ORDER BY added to preserve
stable output order.  I fixed the ones that manifested here, but there
might be some other cases that show up on other platforms.

or target database is being accessed by other users, it tells you whether
the "other users" are live sessions or uncommitted prepared transactions.
(Indeed, it tells you exactly how many of each, but that's mostly just
because it was easy to do so.)  This should help forestall the gotcha of
not realizing that a prepared transaction is what's blocking the command.
Per discussion.

sorting.  The infrastructure for this was all in place already; it's only
necessary to fix the planner to not assume that sorting is always an available
option.

a size that is one of the supported values, not just anything <= sizeof(Datum).
Cross-check the alignment specification against size as well.

read when the --temp-config argument is bad.  Noted while wondering why
buildfarm member dungbeetle is failing ... this isn't why, but it is why
the error report isn't very helpful ...

as per my recent proposal:

1. Fold SortClause and GroupClause into a single node type SortGroupClause.
We were already relying on them to be struct-equivalent, so using two node
tags wasn't accomplishing much except to get in the way of comparing items
with equal().

2. Add an "eqop" field to SortGroupClause to carry the associated equality
operator.  This is cheap for the parser to get at the same time it's looking
up the sort operator, and storing it eliminates the need for repeated
not-so-cheap lookups during planning.  In future this will also let us
represent GROUP/DISTINCT operations on datatypes that have hash opclasses
but no btree opclasses (ie, they have equality but no natural sort order).
The previous representation simply didn't work for that, since its only
indicator of comparison semantics was a sort operator.

3. Add a hasDistinctOn boolean to struct Query to explicitly record whether
the distinctClause came from DISTINCT or DISTINCT ON.  This allows removing
some complicated and not 100% bulletproof code that attempted to figure
that out from the distinctClause alone.

This patch doesn't in itself create any new capability, but it's necessary
infrastructure for future attempts to use hash-based grouping for DISTINCT
and UNION/INTERSECT/EXCEPT.

numbered program.  Per persistent buildfarm failures.

Tom Lane

Robert Lor

method is grouped together in a reasonably similar way, keeping the "global
shared functions" together in their own section as well. Makes it a lot easier
to find your way around the code.

routines, leaving hba.c to deal only with processing the HBA specific files.

to represent DISTINCT or DISTINCT ON.  This gets rid of a longstanding
annoyance that a view or rule using SELECT DISTINCT will be dumped out
with an overspecified ORDER BY list, and is one small step along the way
to decoupling DISTINCT and ORDER BY enough so that hash-based implementation
of DISTINCT will be possible.  In passing, improve transformDistinctClause
so that it doesn't reject duplicate DISTINCT ON items, as was reported by
Steve Midgley a couple weeks ago.

* Consider decreasing the I/O caused by updating tuple hint bits

>   http://archives.postgresql.org/pgsql-patches/2008-07/msg00199.php

or domains).  This was already effectively required because you had to own
the I/O functions, and the I/O functions pretty much have to be written in
C since we don't let PL functions take or return cstring.  But given the
possible security consequences of a malicious type definition, it seems
prudent to enforce superuser requirement directly.  Per recent discussion.

of the STRING type category, thereby opening up the mechanism for user-defined
types.  This is mainly for the benefit of citext, though; there aren't likely
to be a lot of types that are all general-purpose character strings.
Per discussion with David Wheeler.

only type categories in which the previous coding made *every* type
preferred; so there is no change in effective behavior, because the function
resolution rules only do something different when faced with a choice
between preferred and non-preferred types in the same category.  It just
seems safer and less surprising to have CREATE TYPE default to non-preferred
status ...

by putting it into the standard string category, we cause casts from citext
to text to be recognized as "preferred" casts.  This eliminates the need
for creation of alias functions and operators that only serve to prevent
ambiguous-function errors; get rid of the ones that were in the original
commit.

with system catalog lookups, as was foreseen to be necessary almost since
their creation.  Instead put the information into two new pg_type columns,
typcategory and typispreferred.  Add support for setting these when
creating a user-defined base type.

The category column is just a "char" (i.e. a poor man's enum), allowing
a crude form of user extensibility of the category list: just use an
otherwise-unused character.  This seems sufficient for foreseen uses,
but we could upgrade to having an actual category catalog someday, if
there proves to be a huge demand for custom type categories.

In this patch I have attempted to hew exactly to the behavior of the
previous hardwired logic, except for introducing new type categories for
arrays, composites, and enums.  In particular the default preferred state
for user-defined types remains TRUE.  That seems worth revisiting, but it
should be done as a separate patch from introducing the infrastructure.
Likewise, any adjustment of the standard set of categories should be done
separately.

David E. Wheeler

SGML source but in the actual web/pdf viewer...

for building on MSVC, and that the free distribution is enough
(no need for the enterprise version).

Per gripe from Martin Zaun.

filter to be used when INSERT or SELECT INTO has a plan that returns raw
disk tuples.  The virtual-tuple-slot optimizations that were put in place
awhile ago mean that ExecInsert has to do ExecMaterializeSlot, and that
already copies the tuple if it's raw (and does so more efficiently than
a junk filter, too).  So get rid of that logic.  This in turn means that
we can throw away ExecMayReturnRawTuples, which wasn't used for any other
purpose, and was always a kluge anyway.

In passing, move a couple of SELECT-INTO-specific fields out of EState
and into the private state of the SELECT INTO DestReceiver, as was foreseen
in an old comment there.  Also make intorel_receive use ExecMaterializeSlot
not ExecCopySlotTuple, for consistency with ExecInsert and to possibly save
a tuple copy step in some cases.

Per report from César Miguel Oliveira Alves.

Cosmetic, but it might make this a bit less confusing to the next reader.

Simon Riggs

default_reloptions().  The previous coding was really a bug because pg_atoi()
will always throw elog on bad input data, whereas default_reloptions is not
supposed to complain about bad input unless its validate parameter is true.
Right now you could only expose the problem by hand-modifying
pg_class.reloptions into an invalid state, so it doesn't seem worth
back-patching; but we should get it right in HEAD because there might be other
situations in future.  Noted while studying GIN fast-update patch.

This is required because the value is substituted into the pltcl_*mod
scripts.

(Extracted from fast-insert patch, since it ought to be back-patched)

protection.

Simon Riggs

has to deal with.

and bogus documentation (dimension arrays are int[] not anyarray).  Also the
errhint() messages seem to be really errdetail(), since there is nothing
heuristic about them.  Some other trivial cosmetic improvements.

to acquire shared table locks within a specified amount of time.

David Gould

  In psql, run .psqlrc _after_ printing warnings and banner.

the postgres.bki file during build, because we want that file to be entirely
platform- and configuration-independent; else it can't safely be put into
/usr/share on multiarch machines.  We can do the substitution during initdb,
instead.  FLOAT4PASSBYVAL and FLOAT8PASSBYVAL are new breakage as of 8.4,
while the NAMEDATALEN hazard has been there all along but I guess no one
tripped over it.  Noticed while trying to build "universal" OS X binaries.

a portal are never NULL, but reliably provide the source text of the query.
It turns out that there was only one place that was really taking a short-cut,
which was the 'EXECUTE' utility statement.  That doesn't seem like a
sufficiently critical performance hotspot to justify not offering a guarantee
of validity of the portal source text.  Fix it to copy the source text over
from the cached plan.  Add Asserts in the places that set up cached plans and
portals to reject null source strings, and simplify a bunch of places that
formerly needed to guard against nulls.

There may be a few places that cons up statements for execution without
having any source text at all; I found one such in ConvertTriggerToFK().
It seems sufficient to inject a phony source string in such a case,
for instance
        ProcessUtility((Node *) atstmt,
                       "(generated ALTER TABLE ADD FOREIGN KEY command)",
                       NULL, false, None_Receiver, NULL);

We should take a second look at the usage of debug_query_string,
particularly the recently added current_query() SQL function.

ITAGAKI Takahiro and Tom Lane

ITAGAKI Takahiro

ITAGAKI Takahiro

rewrite.  When called from SIInsertDataEntries, SICleanupQueue releases
the write lock if it has to issue a kill() to signal some laggard backend.
That still seems like a good idea --- but it's possible that by the time
we get the lock back, there are no longer enough free message slots to
satisfy SIInsertDataEntries' requirement.  Must recheck, and repeat the
whole SICleanupQueue process if not.  Noted while reading code.

robust.  The previous coding was quite risky because it was testing
conditions different from 'is the array really allocated?'.

(Unlike the original submission, this patch treats TABLE output parameters
as being entirely equivalent to OUT parameters -- tgl)

Pavel Stehule