The new format accepts exactly the same data as the json type. However, it is
stored in a format that does not require reparsing the orgiginal text in order
to process it, making it much more suitable for indexing and other operations.
Insignificant whitespace is discarded, and the order of object keys is not
preserved. Neither are duplicate object keys kept - the later value for a given
key is the only one stored.
The new type has all the functions and operators that the json type has,
with the exception of the json generation functions (to_json, json_agg etc.)
and with identical semantics. In addition, there are operator classes for
hash and btree indexing, and two classes for GIN indexing, that have no
equivalent in the json type.
This feature grew out of previous work by Oleg Bartunov and Teodor Sigaev, which
was intended to provide similar facilities to a nested hstore type, but which
in the end proved to have some significant compatibility issues.
Authors: Oleg Bartunov, Teodor Sigaev, Peter Geoghegan and Andrew Dunstan.
Review: Andres Freund
This adds the following:
json_agg(anyrecord) -> json
to_json(any) -> json
hstore_to_json(hstore) -> json (also used as a cast)
hstore_to_json_loose(hstore) -> json
The last provides heuristic treatment of numbers and booleans.
Also, in json generation, if any non-builtin type has a cast to json,
that function is used instead of the type's output function.
Andrew Dunstan, reviewed by Steve Singer.
Catalog version bumped.
This isn't fully tested as yet, in particular I'm not sure that the
"foo--unpackaged--1.0.sql" scripts are OK. But it's time to get some
buildfarm cycles on it.
sepgsql is not converted to an extension, mainly because it seems to
require a very nonstandard installation process.
Dimitri Fontaine and Tom Lane
Remove the 64K limit on the lengths of keys and values within an hstore.
(This changes the on-disk format, but the old format can still be read.)
Add support for btree/hash opclasses for hstore --- this is not so much
for actual indexing purposes as to allow use of GROUP BY, DISTINCT, etc.
Add various other new functions and operators.
Andrew Gierth
with minor editorization by me.
Hstore improvements
* add operation hstore ? text - excat equivalent of exist()
* remove undocumented behaviour of contains operation with NULL value
* now 'key'::text=>NULL returns '"key"=>NULL' instead of NULL
* Add GIN support for contains and exist operations
* Add GiST support for exist operatiion
* improve regression tests
Andrew Dunstan
Peter Eisentraut
Robert Haas
Tom Lane
Teodor Sigaev