columns, and the new version can be stored on the same heap page, we no longer
generate extra index entries for the new version.  Instead, index searches
follow the HOT-chain links to ensure they find the correct tuple version.

In addition, this patch introduces the ability to "prune" dead tuples on a
per-page basis, without having to do a complete VACUUM pass to recover space.
VACUUM is still needed to clean up dead index entries, however.

Pavan Deolasee, with help from a bunch of other people.

databases, per gripe from hubert depesz lubaczewski.  Patch from
Simon Riggs.

tablespace(s) in which to store temp tables and temporary files.  This is a
list to allow spreading the load across multiple tablespaces (a random list
element is chosen each time a temp object is to be created).  Temp files are
not stored in per-database pgsql_tmp/ directories anymore, but per-tablespace
directories.

Jaime Casanova and Albert Cervera, with review by Bernd Helmle and Tom Lane.

Teodor Sigaev, with some kibitzing from Tom Lane.

CONCURRENTLY.

Gregory Stark

Standard English uses "may", "can", and "might" in different ways:

        may - permission, "You may borrow my rake."

        can - ability, "I can lift that log."

        might - possibility, "It might rain today."

Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice.  Similarly, "It may crash" is better stated, "It might crash".

per-column options for btree indexes.  The planner's support for this is still
pretty rudimentary; it does not yet know how to plan mergejoins with
nondefault ordering options.  The documentation is pretty rudimentary, too.
I'll work on improving that stuff later.

Note incompatible change from prior behavior: ORDER BY ... USING will now be
rejected if the operator is not a less-than or greater-than member of some
btree opclass.  This prevents less-than-sane behavior if an operator that
doesn't actually define a proper sort ordering is selected.

CONCURRENTLY.  Greg Stark, some further tweaks by me.

blocking concurrent writes to the table.  Greg Stark, with a little help
from Tom Lane.

it can handle small fillfactors for ordinary-sized index entries without
failing on large ones; fix nbtinsert.c to distinguish leaf and nonleaf
pages; change the minimum fillfactor to 10% for all index types.

ITAGAKI Takahiro

clause implicitly whenever one is not given explicitly.  Remove concept
of a schema having an associated tablespace, and simplify the rules for
selecting a default tablespace for a table or index.  It's now just
(a) explicit TABLESPACE clause; (b) default_tablespace if that's not an
empty string; (c) database's default.  This will allow pg_dump to use
SET commands instead of tablespace clauses to determine object locations
(but I didn't actually make it do so).  All per recent discussions.

some other examples for CREATE DATABASE.

Gavin Sherry

There are various things left to do: contrib dbsize and oid2name modules
need work, and so does the documentation.  Also someone should think about
COMMENT ON TABLESPACE and maybe RENAME TABLESPACE.  Also initlocation is
dead, it just doesn't know it yet.

Gavin Sherry and Tom Lane.

> >> have to accept a full table scan when locating records.
> >
> > It indexes them, but "is null" is not an indexable operator, so you
> > can't directly solve the above with a 3-column index.  What you can do
> > instead is use a partial index, for instance
> >
> > create index i on CUSTOMER.WCCustOrderStatusLog (WCOrderStatusID)
> > where Acknowledged is null and Processing is null;
>
> That's a very nifty trick and exactly the sort of answer I was after!

Add CREATE INDEX doc mention of using partial indexes for IS NULL
indexing;  idea from Tom.

$Header: -> $PostgreSQL Changes ...

makes a few more small improvements to runtime.sgml, and makes some SGML
conventions more consistent.

Neil Conway

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

of an index can now be a computed expression instead of a simple variable.
Restrictions on expressions are the same as for predicates (only immutable
functions, no sub-selects).  This fixes problems recently introduced with
inlining SQL functions, because the inlining transformation is applied to
both expression trees so the planner can still match them up.  Along the
way, improve efficiency of handling index predicates (both predicates and
index expressions are now cached by the relcache) and fix 7.3 oversight
that didn't record dependencies of predicate expressions.

OPERATOR CLASS commands.  Further tweaking of documentation for same.

 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.