and revert documentation to describe the existing INHERITS clause
instead, per recent discussion in pghackers.  Also fix implementation
of SQL_inheritance SET variable: it is not cool to look at this var
during the initial parsing phase, only during parse_analyze().  See
recent bug report concerning misinterpretation of date constants just
after a SET TIMEZONE command.  gram.y really has to be an invariant
transformation of the query string to a raw parsetree; anything that
can vary with time must be done during parse analysis.

comparison does not consider paths different when they differ only in
uninteresting aspects of sort order.  (We had a special case of this
consideration for indexscans already, but generalize it to apply to
ordered join paths too.)  Be stricter about what is a canonical pathkey
to allow faster pathkey comparison.  Cache canonical pathkeys and
dispersion stats for left and right sides of a RestrictInfo's clause,
to avoid repeated computation.  Total speedup will depend on number of
tables in a query, but I see about 4x speedup of planning phase for
a sample seven-table query.

avoid repeated evaluations in cost_qual_eval().  This turns out to save
a useful fraction of planning time.  No change to external representation
of RestrictInfo --- although that node type doesn't appear in stored
rules anyway.

non-standard clauses.  Allow CHARACTERISTICS as unquoted identifier.
Merge related reference pages.

cloned, rather than always cloning template1.  Modify initdb to generate
two identical databases rather than one, template0 and template1.
Connections to template0 are disallowed, so that it will always remain
in its virgin as-initdb'd state.  pg_dumpall now dumps databases with
restore commands that say CREATE DATABASE foo WITH TEMPLATE = template0.
This allows proper behavior when there is user-added data in template1.
initdb forced!

joins, and clean things up a good deal at the same time.  Append plan node
no longer hacks on rangetable at runtime --- instead, all child tables are
given their own RT entries during planning.  Concept of multiple target
tables pushed up into execMain, replacing bug-prone implementation within
nodeAppend.  Planner now supports generating Append plans for inheritance
sets either at the top of the plan (the old way) or at the bottom.  Expanding
at the bottom is appropriate for tables used as sources, since they may
appear inside an outer join; but we must still expand at the top when the
target of an UPDATE or DELETE is an inheritance set, because we actually need
a different targetlist and junkfilter for each target table in that case.
Fortunately a target table can't be inside an outer join...  Bizarre mutual
recursion between union_planner and prepunion.c is gone --- in fact,
union_planner doesn't really have much to do with union queries anymore,
so I renamed it grouping_planner.

Auto removing of offline log files and creating new file
at checkpoint time.

the grammar did not allow redundant parentheses around sub-selects.
Distinguish LIMIT ALL from LIMIT 0; make the latter behave as one would
expect.

position() and substring() functions, so that it works transparently for
bit types as well.  Alias the text functions appropriately.

Add position() for bit types.

Add new constant node T_BitString that represents literals of the form
B'1001 and pass those to zpbit type.

This patch forces the use of 'DROP VIEW' to destroy views.

It also changes the syntax of DROP VIEW to
DROP VIEW v1, v2, ...
to match the syntax of DROP TABLE.

Some error messages were changed so this patch also includes changes to the
appropriate expected/*.out files.

Doc changes for 'DROP TABLE" and 'DROP VIEW' are included.


--
Mark Hollomon

took some rejiggering of typename and ACL parsing, as well as moving
parse_analyze call out of parser().  Restructure postgres.c processing
so that parse analysis and rewrite are skipped when in abort-transaction
state.  Only COMMIT and ABORT statements will be processed beyond the raw
parser() phase.  This addresses problem of parser failing with database access
errors while in aborted state (see pghackers discussions around 7/28/00).
Also fix some bugs with COMMIT/ABORT statements appearing in the middle of
a single query input string.
Function, operator, and aggregate arguments/results can now use full
TypeName production, in particular foo[] for array types.
DROP OPERATOR and COMMENT ON OPERATOR were broken for unary operators.
Allow CREATE AGGREGATE to accept unquoted numeric constants for initcond.

SQL92 semantics, including support for ALL option.  All three can be used
in subqueries and views.  DISTINCT and ORDER BY work now in views, too.
This rewrite fixes many problems with cross-datatype UNIONs and INSERT/SELECT
where the SELECT yields different datatypes than the INSERT needs.  I did
that by making UNION subqueries and SELECT in INSERT be treated like
subselects-in-FROM, thereby allowing an extra level of targetlist where the
datatype conversions can be inserted safely.
INITDB NEEDED!

(Don't forget that an alias is required.)  Views reimplemented as expanding
to subselect-in-FROM.  Grouping, aggregates, DISTINCT in views actually
work now (he says optimistically).  No UNION support in subselects/views
yet, but I have some ideas about that.  Rule-related permissions checking
moved out of rewriter and into executor.
INITDB REQUIRED!

ends to clean up (see my message of same date to pghackers), but mostly
it works.  INITDB REQUIRED!

including utility statements.  Still can't copy or compare executor
state, but at present that doesn't seem to be necessary.  This makes
it possible to execute most (all?) utility statements in plpgsql.
Had to change parsetree representation of CreateTrigStmt so that it
contained only legal Nodes, and not bare string constants.

from Param nodes, per discussion a few days ago on pghackers.  Add new
expression node type FieldSelect that implements the functionality where
it's actually needed.  Clean up some other unused fields in Func nodes
as well.
NOTE: initdb forced due to change in stored expression trees for rules.

a very long time.

There's now only one transition value and transition function.
NULL handling in aggregates is a lot cleaner.  Also, use Numeric
accumulators instead of integer accumulators for sum/avg on integer
datatypes --- this avoids overflow at the cost of being a little slower.
Implement VARIANCE() and STDDEV() aggregates in the standard backend.

Also, enable new LIKE selectivity estimators by default.  Unrelated
change, but as long as I had to force initdb anyway...

memory contexts.  Currently, only leaks in expressions executed as
quals or projections are handled.  Clean up some old dead cruft in
executor while at it --- unused fields in state nodes, that sort of thing.

in copyfuncs and equalfuncs exposed by regression tests.  We still have
some work to do: these modules really ought to handle most or all of
the utility statement node types.  But it's better than it was.

costs using the inner path's parent->rows count as the number of tuples
processed per inner scan iteration.  This is wrong when we are using an
inner indexscan with indexquals based on join clauses, because the rows
count in a Relation node reflects the selectivity of the restriction
clauses for that rel only.  Upshot was that if join clause was very
selective, we'd drastically overestimate the true cost of the join.
Fix is to calculate correct output-rows estimate for an inner indexscan
when the IndexPath node is created and save it in the path node.
Change of path node doesn't require initdb, since path nodes don't
appear in saved rules.

integers) to be strings instead of 'double'.  We convert from string form
to internal representation only after type resolution has determined the
correct type for the constant.  This eliminates loss-of-precision worries
and gets rid of the change in behavior seen at 17 digits with the
previous kluge.

represent the result of a binary-compatible type coercion.  At runtime
it just evaluates its argument --- but during type resolution, exprType
will pick up the output type of the RelabelType node instead of the type
of the argument.  This solves some longstanding problems with dropped
type coercions, an example being 'select now()::abstime::int4' which
used to produce date-formatted output, not an integer, because the
coercion to int4 was dropped on the floor.

accesses versus sequential accesses, a (very crude) estimate of the
effects of caching on random page accesses, and cost to evaluate WHERE-
clause expressions.  Export critical parameters for this model as SET
variables.  Also, create SET variables for the planner's enable flags
(enable_seqscan, enable_indexscan, etc) so that these can be controlled
more conveniently than via PGOPTIONS.

Planner now estimates both startup cost (cost before retrieving
first tuple) and total cost of each path, so it can optimize queries
with LIMIT on a reasonable basis by interpolating between these costs.
Same facility is a win for EXISTS(...) subqueries and some other cases.

Redesign pathkey representation to achieve a major speedup in planning
(I saw as much as 5X on a 10-way join); also minor changes in planner
to reduce memory consumption by recycling discarded Path nodes and
not constructing unnecessary lists.

Minor cleanups to display more-plausible costs in some cases in
EXPLAIN output.

Initdb forced by change in interface to index cost estimation
functions.

  SELECT a FROM t1 tx (a);
Allow join syntax, including queries like
  SELECT * FROM t1 NATURAL JOIN t2;
Update RTE structure to hold column aliases in an Attr structure.

fields in JoinPaths --- turns out that we do need that after all :-(.
Also, rearrange planner so that only one RelOptInfo is created for a
particular set of joined base relations, no matter how many different
subsets of relations it can be created from.  This saves memory and
processing time compared to the old method of making a bunch of RelOptInfos
and then removing the duplicates.  Clean up the jointree iteration logic;
not sure if it's better, but I sure find it more readable and plausible
now, particularly for the case of 'bushy plans'.

nodes...

SELECT DISTINCT ON (expr [, expr ...]) targetlist ...
and there is a check to make sure that the user didn't specify an ORDER BY
that's incompatible with the DISTINCT operation.
Reimplement nodeUnique and nodeGroup to use the proper datatype-specific
equality function for each column being compared --- they used to do
bitwise comparisons or convert the data to text strings and strcmp().
(To add insult to injury, they'd look up the conversion functions once
for each tuple...)  Parse/plan representation of DISTINCT is now a list
of SortClause nodes.
initdb forced by querytree change...

  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc

to all files copyright Regents of Berkeley.  Man, that's a lot of files.

code cleanup; no major improvements yet.  However, EXPLAIN does produce
more intuitive outputs for nested loops with indexscans now...

	SELECT null::text;
	SELECT int4fac(null);
work as expected now.  In some cases a NULL must be surrounded by
parentheses:
	SELECT 2 + null;                 fails
	SELECT 2 + (null);               OK
This is a grammatical ambiguity that seems difficult to avoid.  Other
than that, NULLs seem to behave about like you'd expect.  The internal
implementation is that NULL constants are typed as UNKNOWN (like
untyped string constants) until the parser can deduce the right type.

Note this forces initdb because of change of Aggref node in stored rules.

mentioned in FROM but not elsewhere in the query: such tables should be
joined over anyway.  Aside from being more standards-compliant, this allows
removal of some very ugly hacks for COUNT(*) processing.  Also, allow
HAVING clause without aggregate functions, since SQL does.  Clean up
CREATE RULE statement-list syntax the same way Bruce just fixed the
main stmtmulti production.
CAUTION: addition of a field to RangeTblEntry nodes breaks stored rules;
you will have to initdb if you have any rules.

Frankpitt, plus some improvements from yours truly.  The simplifier depends
on the proiscachable field of pg_proc to tell it whether a function is
safe to pre-evaluate --- things like nextval() are not, for example.
Update pg_proc.h to contain reasonable cacheability information; as of
6.5.* hardly any functions were marked cacheable.  I may have erred too
far in the other direction; see recent mail to pghackers for more info.
This update does not force an initdb, exactly, but you won't see much
benefit from the simplifier until you do one.

sort order down into planner, instead of handling it only at the very top
level of the planner.  This fixes many things.  An explicit sort is now
avoided if there is a cheaper alternative (typically an indexscan) not
only for ORDER BY, but also for the internal sort of GROUP BY.  It works
even when there is no other reason (such as a WHERE condition) to consider
the indexscan.  It works for indexes on functions.  It works for indexes
on functions, backwards.  It's just so cool...

CAUTION: I have changed the representation of SortClause nodes, therefore
THIS UPDATE BREAKS STORED RULES.  You will need to initdb.

store all ordering information in pathkeys lists (which are now lists of
lists of PathKeyItem nodes, not just lists of lists of vars).  This was
a big win --- the code is smaller and IMHO more understandable than it
was, even though it handles more cases.  I believe the node changes will
not force an initdb for anyone; planner nodes don't show up in stored
rules.