Commit 8cb53654, which introduced DROP
INDEX CONCURRENTLY, managed to break CREATE INDEX CONCURRENTLY via a poor
choice of catalog state representation.  The pg_index state for an index
that's reached the final pre-drop stage was the same as the state for an
index just created by CREATE INDEX CONCURRENTLY.  This meant that the
(necessary) change to make RelationGetIndexList ignore about-to-die indexes
also made it ignore freshly-created indexes; which is catastrophic because
the latter do need to be considered in HOT-safety decisions.  Failure to
do so leads to incorrect index entries and subsequently wrong results from
queries depending on the concurrently-created index.

To fix, make the final state be indisvalid = true and indisready = false,
which is otherwise nonsensical.  This is pretty ugly but we can't add
another column without forcing initdb, and it's too late for that in 9.2.
(There's a cleaner fix in HEAD.)

In addition, change CREATE/DROP INDEX CONCURRENTLY so that the pg_index
flag changes they make without exclusive lock on the index are made via
heap_inplace_update() rather than a normal transactional update.  The
latter is not very safe because moving the pg_index tuple could result in
concurrent SnapshotNow scans finding it twice or not at all, thus possibly
resulting in index corruption.  This is a pre-existing bug in CREATE INDEX
CONCURRENTLY, which was copied into the DROP code.

In addition, fix various places in the code that ought to check to make
sure that the indexes they are manipulating are valid and/or ready as
appropriate.  These represent bugs that have existed since 8.2, since
a failed CREATE INDEX CONCURRENTLY could leave a corrupt or invalid
index behind, and we ought not try to do anything that might fail with
such an index.

Also fix RelationReloadIndexInfo to ensure it copies all the pg_index
columns that are allowed to change after initial creation.  Previously we
could have been left with stale values of some fields in an index relcache
entry.  It's not clear whether this actually had any user-visible
consequences, but it's at least a bug waiting to happen.

In addition, do some code and docs review for DROP INDEX CONCURRENTLY;
some cosmetic code cleanup but mostly addition and revision of comments.

Portions of this need to be back-patched even further, but I'll work
on that separately.

Problem reported by Amit Kapila, diagnosis by Pavan Deolasee,
fix by Tom Lane and Andres Freund.

There is what may actually be a mistake in our markup.  The problem is
in a situation like

<para>
 <command>FOO</command> is ...

there is strictly speaking a line break before "FOO".  In the HTML
output, this does not appear to be a problem, but in the man page
output, this shows up, so you get double blank lines at odd places.

So far, we have attempted to work around this with an XSL hack, but
that causes other problems, such as creating run-ins in places like

<acronym>SQL</acronym> <command>COPY</command>

So fix the problem properly by removing the extra whitespace.  I only
fixed the problems that affect the man page output, not all the
places.

The endterm attribute is mainly useful when the toolchain does not support
automatic link target text generation for a particular situation.  In  the
past, this was required by the man page tools for all reference page links,
but that is no longer the case, and it now actually gets in the way of
proper automatic link text generation.  The only remaining use cases are
currently xrefs to refsects.

another section if required by the platform (instead of the old way of
building them in section "l" and always transforming them to the
platform-specific section).

This speeds up the installation on common platforms, and it avoids some
funny business with the man page tools and build process.

DROP objecttype IF EXISTS for the following objects:
  table view index sequence schema type domain conversion

$Header: -> $PostgreSQL Changes ...

discussion.  (Still have some work to do editing the remainder.)

identifier, while some areas do not.

The attached converts be below to "name":
conversion_name
index_name


The below have an existing, initdb supplied, entity named "name".  As
such, it could be confusing for the reader to see that identifier used
in the example.

domainname
typename

Rod Taylor

pg_relcheck is gone; CHECK, UNIQUE, PRIMARY KEY, and FOREIGN KEY
constraints all have real live entries in pg_constraint.  pg_depend
exists, and RESTRICT/CASCADE options work on most kinds of DROP;
however, pg_depend is not yet very well populated with dependencies.
(Most of the ones that are present at this point just replace formerly
hardwired associations, such as the implicit drop of a relation's pg_type
entry when the relation is dropped.)  Need to add more logic to create
dependency entries, improve pg_dump to dump constraints in place of
indexes and triggers, and add some regression tests.

 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.

 between Postgres and PostgreSQL.

===================
In Notes:
 Refer to CREATE FUNCTION for information on creating aggregate functions.
                                                      ^^^^^^^^^^^^^^^^^^^
I assume it must read C function instead.

In Compatibility SQL/PSM:
 SQL/PSM is a proposed standard.

 We had that before: remove proposed.


drop_index.sgml:
================
<REFNAME>: Removes existing indexes from a database

as far as I can see index should be singular. The command description is
written as if only one index can be removed at a time. Interestingly
enough, in v7.0.2 it was in fact singular. Am I mistaken here?

drop_operator.sgml:
===================
In Outputs the arguments are referred to as type and type2, but the synopsis
and Inputs section these are left_type and right_type, respectively. Also,
oper is used in Outputs versus id in Inputs/Synopsis. In the translation I
follow the replaceables used in the Inputs/Synopsis part.

Frank Wegmann

as well allow DROP multiple INDEX, RULE, TYPE as well.  Add missing
CommandCounterIncrement to DROP loop, which could cause trouble otherwise
with multiple DROP of items affecting same catalog entries.  Try to
bring a little consistency to various error messages using 'does not exist',
'nonexistent', etc --- I standardized on 'does not exist' since that's
what the vast majority of the existing uses seem to be.

ecpg reference page still needs formatting.

No big deal; fixed lots of other markup at the same time.
Bigest change: make sure there is no whitespace
 in front of <term> contents.
This will probably help the other output types too.

 of Norm's Modular Style Sheets and jade/docbook.
From Vince Vielhaber <vev@michvhf.com>.

 for SQL commands.