* Defined new struct WordEntryPosVector that holds a uint16 length and a
variable size array of WordEntries. This replaces the previous
convention of a variable size uint16 array, with the first element
implying the length. WordEntryPosVector has the same layout in memory,
but is more readable in source code. The POSDATAPTR and POSDATALEN
macros are still used, though it would now be more readable to access
the fields in WordEntryPosVector directly.

* Removed needfree field from DocRepresentation. It was always set to false.

* Miscellaneous other commenting and refactoring

small editorization by me

- Brake the QueryItem struct into QueryOperator and QueryOperand.
  Type was really the only common field between them. QueryItem still
  exists, and is used in the TSQuery struct as before, but it's now a
  union of the two. Many other changes fell from that, like separation
  of pushval_asis function into pushValue, pushOperator and pushStop.

- Moved some structs that were for internal use only from header files
  to the right .c-files.

- Moved tsvector parser to a new tsvector_parser.c file. Parser code was
  about half of the size of tsvector.c, it's also used from tsquery.c, and
  it has some data structures of its own, so it seems better to separate
  it. Cleaned up the API so that TSVectorParserState is not accessed from
  outside tsvector_parser.c.

- Separated enumerations (#defines, really) used for QueryItem.type
  field and as return codes from gettoken_query. It was just accidental
  code sharing.

- Removed ParseQueryNode struct used internally by makepol and friends.
  push*-functions now construct QueryItems directly.

- Changed int4 variables to just ints for variables like "i" or "array
  size", where the storage-size was not significant.

objects to it.

Oleg Bartunov and Teodor Sigaev, but I did a lot of editorializing,
so anything that's broken is probably my fault.

Documentation is nonexistent as yet, but let's land the patch so we can
get some portability testing done.

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

sizebitvec of tsearch2, as well as identical code in several other
contrib modules.  This provided about a 20X speedup in building a
large tsearch2 index ... didn't try to measure its effects for other
operations.  Thanks to Stephan Vollmer for providing a test case.

methods in a short-lived memory context, there is no need for GiST methods
to do their own manual (and error-prone) memory management.

2 implement gtsvector_out for use with gevel module (debug GiST indexes, http://www.sai.msu.su/~megera/postgres/gist/gevel/)

getting rid of numerous ad-hoc versions that have popped up in various
places.  Shortens code and avoids conflict with Windows min() and max()
macros.

boxes. Change interface to user-defined GiST support methods union and
picksplit. Now instead of bytea struct it used special GistEntryVector
structure.

Teodor Sigaev

Teodor Sigaev <teodor@stack.net>.

From Oleg Bartunov and Teodor Sigaev.