representation of equivalence classes of variables. This is an extensive
rewrite, but it brings a number of benefits:
* planner no longer fails in the presence of "incomplete" operator families
that don't offer operators for every possible combination of datatypes.
* avoid generating and then discarding redundant equality clauses.
* remove bogus assumption that derived equalities always use operators
named "=".
* mergejoins can work with a variety of sort orders (e.g., descending) now,
instead of tying each mergejoinable operator to exactly one sort order.
* better recognition of redundant sort columns.
* can make use of equalities appearing underneath an outer join.
The implementation is somewhat ugly logic-wise, but I don't see an
easy way to make it more concise.
When writing this, I noticed that my previous implementation of
width_bucket() doesn't handle NaN correctly:
postgres=# select width_bucket('NaN', 1, 5, 5);
width_bucket
--------------
6
(1 row)
AFAICS SQL:2003 does not define a NaN value, so it doesn't address how
width_bucket() should behave here. The patch changes width_bucket() so
that ereport(ERROR) is raised if NaN is specified for the operand or the
lower or upper bounds to width_bucket(). For float8, NaN is disallowed
for any of the floating-point inputs, and +/- infinity is disallowed
for the histogram bounds (but allowed for the operand).
Update docs and regression tests, bump the catversion.
standard convention the 21st century runs from 2001-2100, not 2000-2099,
so make it work like that. Per bug #2885 from Akio Iwaasa.
Backpatch to 8.2, but no further, since this is really a definitional
change; users of older branches are probably more interested in stability.
< * Allow the creation of indexes with mixed ascending/descending
> * -Allow the creation of indexes with mixed ascending/descending
<
< This is possible now by creating an operator class with reversed sort
< operators. One complexity is that NULLs would then appear at the start
< of the result set, and this might affect certain sort types, like
< merge join.
<
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.
< * Improve the MONEY data type
> * -Make 64-bit version of the MONEY data type
> * Add locale-aware MONEY type, and support multiple currencies
< Change the MONEY data type to use DECIMAL internally, with special
< locale-aware output formatting.
< http://archives.postgresql.org/pgsql-hackers/2006-09/msg01107.php
>
> * Make consistent use of long/short command options --- pg_ctl needs
> long ones, pg_config doesn't have short ones, postgres doesn't have
> enough long ones, etc.
> o Consider parsing the -c string into individual queries so each
> is run in its own transaction
>
> o Consider disallowing multiple queries in PQexec() as an
> additional barrier to SQL injection attacks
< * Allow inherited tables to inherit index, UNIQUE constraint, and primary
< key, foreign key
< * UNIQUE INDEX on base column not honored on INSERTs/UPDATEs from
< inherited table: INSERT INTO inherit_table (unique_index_col) VALUES
< (dup) should fail
<
< The main difficulty with this item is the problem of creating an index
< that can span more than one table.
<
< * Allow SELECT ... FOR UPDATE on inherited tables
> * Inheritance
>
> o Allow inherited tables to inherit indexes, UNIQUE constraints,
> and primary/foreign keys
> o Honor UNIQUE INDEX on base column in INSERTs/UPDATEs
> on inherited table, e.g. INSERT INTO inherit_table
> (unique_index_col) VALUES (dup) should fail
>
> The main difficulty with this item is the problem of
> creating an index that can span multiple tables.
>
> o Allow SELECT ... FOR UPDATE on inherited tables
>
>
>
Tom Lane
Peter Eisentraut
Neil Conway
Bruce Momjian
Alvaro Herrera