detection.

pseudo-type record[] to represent arrays of possibly-anonymous composite
types.  Since composite datums carry their own type identification, no
extra knowledge is needed at the array level.

The main reason for doing this right now is that it is necessary to support
the general case of detection of cycles in recursive queries: if you need to
compare more than one column to detect a cycle, you need to compare a ROW()
to an array built from ROW()s, at least if you want to do it as the spec
suggests.  Add some documentation and regression tests concerning the cycle
detection issue.

RecursiveUnion to which it refers.  It turns out that we can just postpone the
relevant initialization steps until the first exec call for the node, by which
time the ancestor node must surely be initialized.  Per report from Greg Stark.

Per gripe from Bill Thoen.

for bitmap index scans.  Per report and test case from Kevin Grittner.

Depesz Lubaczewski.  In HEAD, also move a couple of other cases to make the
code ordering match up with ProcessUtility.

it can handle functions returning setof record.  The case was left undone
originally, but it turns out to be simple to fix.

the ereport macro.  Included in this commit are enough files for starting
plpgsql, plpython, plperl and pltcl translations.

the isTrigger state explicitly, not rely on nonzero-ness of trigrelOid
to indicate trigger-hood, because trigrelOid will be left zero when compiling
for validation.  The (useless) function hash entry built by the validator
was able to match an ordinary non-trigger call later in the same session,
thereby bypassing the check that is supposed to prevent such a call.
Per report from Alvaro.

It might be worth suppressing the useless hash entry altogether, but
that's a bigger change than I want to consider back-patching.

Back-patch to 8.0.  7.4 doesn't have the problem because it doesn't
have validation mode.

Report and fix by Michael McMaster.  Some minor code beautification by me,
also avoid memory leaks in the special-case paths.

to process any pending unlinks for the source database.

Before, if you dropped a relation in the template database just before
CREATE DATABASE, and a checkpoint happened during copydir(), the checkpoint
might delete a file that we're just about to copy, causing lstat() in
copydir() to fail with ENOENT.

Backpatch to 8.3, where the pending unlinks were introduced.

Per report by Matthew Wakeling and analysis by Tom Lane.

of referencing a WITH item that's not yet in scope according to the SQL
spec's semantics.  This seems to be an easy error to make, and the bare
"relation doesn't exist" message doesn't lead one's mind in the correct
direction to fix it.

Jun Kuwamura

implementation uses an in-memory hash table, so it will poop out for very
large recursive results ... but the performance characteristics of a
sort-based implementation would be pretty unpleasant too.

use the old relfilenode in the new tablespace. There might be another relation
in the new tablespace with the same relfilenode, so we must generate a fresh
relfilenode in the new tablespace.

The 8.3 patch to let deleted relation files linger as zero-length files until
the next checkpoint made this more obvious: moving a relation from one table
space another, and then back again, caused a collision with the lingering
file.

Back-patch to 8.1. The issue is present in 8.0 as well, but it doesn't seem
worth fixing there, because we didn't have protection from OID collisions
after OID wraparound before 8.1.

Report by Guillaume Lelarge.

supplies an expression that can't be coerced to the target column type.
The code previously attempted to point at the target column name, which
doesn't work at all in an INSERT with omitted column name list, and is
also not remarkably helpful when the problem is buried somewhere in a
long INSERT-multi-VALUES command.  Make it point at the failed expression
instead.

tuplestore: in READFILE state tuplestore_select_read_pointer must
save the current file seek position in the read pointer being
deactivated.

get_name_for_var_field didn't have enough context to interpret a reference to
a CTE query's output.  Fixing this requires separate hacks for the regular
deparse case (pg_get_ruledef) and for the EXPLAIN case, since the available
context information is quite different.  It's pretty nearly parallel to the
existing code for SUBQUERY RTEs, though.  Also, add code to make sure we
qualify a relation name that matches a CTE name; else the CTE will mistakenly
capture the reference when reloading the rule.

In passing, fix a pre-existing problem with get_name_for_var_field not working
on variables in targetlists of SubqueryScan plan nodes.  Although latent all
along, this wasn't a problem until we made EXPLAIN VERBOSE try to print
targetlists.  To do this, refactor the deparse_context_for_plan API so that
the special case for SubqueryScan is all on ruleutils.c's side.

the column alias names of the RTE referenced by the Var to the RowExpr.
This is needed to allow ruleutils.c to correctly deparse FieldSelect nodes
referencing such a construct.  Per my recent bug report.

Adding a field to RowExpr forces initdb (because of stored rules changes)
so this solution is not back-patchable; which is unfortunate because 8.2
and 8.3 have this issue.  But it only affects EXPLAIN for some pretty odd
corner cases, so we can probably live without a solution for the back
branches.

from a query level above the current ParseState.

relation forks. While the file names are not visible to users, for those
that do peek into the data directory, it's nice to have more descriptive
names. Per Greg Stark's suggestion.

the value a parameter has at server start and will have after RESET,
respectively.

Greg Smith, with some modifications by me.

maybe isalnum is returning a value with the low-order byte all zero?

well as regular tables.  Per discussion, this seems necessary to meet the
principle of least astonishment.

In passing, simplify the error messages in warnAutoRange().  Now that we
have parser error position info for these errors, it doesn't seem very
useful to word the error message differently depending on whether we are
inside a sub-select or not.

machine produces zero (rather than the more usual minimum-possible-integer)
for the only possible overflow case.  This has been seen to occur for at least
some word widths on some hardware, and it's cheap enough to check for
everywhere.  Per Peter's analysis of buildfarm reports.

This could be back-patched, but in the absence of any gripes from the field
I doubt it's worth the trouble.

non-recursive term.  Per an example from Dickson S. Guedes.