The main motivation for changing this is bug #4921, in which it's pointed out
that it's no longer safe to apply ltree operations to the result of
ARRAY(SELECT ...) if the sub-select might return no rows. Before 8.3,
the ARRAY() construct would return NULL, which might or might not be helpful
but at least it wouldn't result in an error. Now it returns an empty array
which results in a failure for no good reason, since the ltree operations
are all perfectly capable of dealing with zero-element arrays.
As far as I can find, these ltree functions are the only places where zero
array dimensionality is rejected unnecessarily.
Back-patch to 8.3 to prevent behavioral regression of queries that worked
in older releases.
ways. I'm not totally sure that I caught everything, but at least now they pass
their regression tests with VARSIZE/SET_VARSIZE defined to reverse byte order.
* new split algorithm (as proposed in http://archives.postgresql.org/pgsql-hackers/2006-06/msg00254.php)
* possible call pickSplit() for second and below columns
* add spl_(l|r)datum_exists to GIST_SPLITVEC -
pickSplit should check its values to use already defined
spl_(l|r)datum for splitting. pickSplit should set
spl_(l|r)datum_exists to 'false' (if they was 'true') to
signal to caller about using spl_(l|r)datum.
* support for old pickSplit(): not very optimal
but correct split
* remove 'bytes' field from GISTENTRY: in any case size of
value is defined by it's type.
* split GIST_SPLITVEC to two structures: one for using in picksplit
and second - for internal use.
* some code refactoring
* support of subsplit to rtree opclasses
TODO: add support of subsplit to contrib modules
boxes. Change interface to user-defined GiST support methods union and
picksplit. Now instead of bytea struct it used special GistEntryVector
structure.
ltree_73.patch.gz - for 7.3 :
Fix ~ operation bug: eg '1.1.1' ~ '*.1'
ltree_74.patch.gz - for current CVS
Fix ~ operation bug: eg '1.1.1' ~ '*.1'
Add ? operation
Optimize index storage
Last change needs drop/create all ltree indexes, so only for 7.4
Teodor Sigaev
