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

pointers, which simplifies the code.  This was not possible in 9.0 because
everything was in a single nested struct, but is possible now.

Per suggestion from Tom.

Don't insist on pg_dumpall and psql being present in the old cluster,
since they are not needed.  Do insist on pg_resetxlog being present
(in both old and new), since we need it.  Also check for pg_config,
but only in the new cluster.  Remove the useless attempt to call
pg_config in the old cluster; we don't need to know the old value of
--pkglibdir.  (In the case of a stripped-down migration installation
there might be nothing there to look at anyway, so any future change
that might reintroduce that need would have to be considered carefully.)

Per my attempts to build a minimal previous-version installation to support
pg_upgrade.

It appears that this will be faster for all but the shortest strings;
at least one some platforms, memcmp() can use word-at-a-time comparisons.

Noah Misch, somewhat pared down.

After parsing a parenthesized subexpression, we must pop all pending
ANDs and NOTs off the stack, just like the case for a simple operand.
Per bug #5793.

Also fix clones of this routine in contrib/intarray and contrib/ltree,
where input of types query_int and ltxtquery had the same problem.

Back-patch to all supported versions.

This patch replaces Guttman's generalized split method with a simple
sort-by-center-points algorithm.  Since the data is only one-dimensional
we don't really need the slow and none-too-stable Guttman method.

This is in part a bug fix, since seg has the same size_alpha versus
size_beta typo that was recently fixed in contrib/cube.  It seems
prudent to apply this rather aggressive fix only in HEAD, though.
Back branches will just get the typo fix.

Alexander Korotkov, reviewed by Yeb Havinga

documentation.  (Many were left over from the old pg_migrator naming.)

1. Don't reimplement S_ISDIR() and S_ISREG() badly.
2. Don't reimplement access() badly.

This code appears to have been copied from ancient versions of the
corresponding backend routines, and not patched to incorporate subsequent
fixes (see my commits of 2008-03-31 and 2010-01-14 respectively).
It might be a good idea to change it to just *call* those routines,
but for now I'll just transpose these fixes over.

Teodor Sigaev, with some revision by Tom

Fujii Masao

KaiGai Kohei, with a few changes by me.

Most of the functions that execute XPath queries leaked the data structures
created by libxml2.  This memory would not be recovered until end of
session, so it mounts up pretty quickly in any serious use of the feature.
Per report from Pavel Stehule, though this isn't his patch.

Back-patch to all supported branches.

except creating new connections.

This eliminates the need for inefficient implementions of this
functionality in both contrib/dblink and contrib/tablefunc, so remove
them.  The upcoming patch implementing an in-core format() function
will also require this functionality.

In passing, add some regression tests.

Alexander Korotkov

Itagaki Takahiro, with slight modifications.

Having this in src/include/port.h makes no sense, now that copydir.c lives
in src/backend/strorage rather than src/port.  Along the way, remove an
obsolete comment from contrib/pg_upgrade that makes reference to the old
location.

Replace for loops in makefiles with proper dependencies.  Parallel
make can now span across directories.  Also, make -k and make -q work
properly.

GNU make 3.80 or newer is now required.

Dirk Heinrichs

Problem reported, and cause identified, by Hernan Gonzalez.

After much expenditure of effort, we've got this to the point where the
performance penalty is pretty minimal in typical cases.

Andrew Dunstan, reviewed by Brendan Jurd, Dean Rasheed, and Tom Lane

Spotted by Alexander Korotkov.

Along the way, remove a misleading comment line.

following NULL check was never reached.

This problem was found by Coccinelle (null_ref.cocci from coccicheck).

Marti Raudsepp

Jan Otto, reviewed by Peter Geoghegan

pg_upgrade slowness for 150k tables.

scandir() with a pattern for every table.

Optimization after report of pg_upgrade slowness with 150k tables.

than packing everything into 'ctx' and passing that to every function.