Typed hstore proposal

Hi all,

I mean to create a typed hstore, called tstore for now. I'm open to
name suggestions. It'll only support a subset of core Postgres types
to begin with. Keys are always text, it's the value that's typed.

Usage is very similar to hstore; this is not a complete reference.

tstore( text, text) Creates a text key-value pair.

tstore( text, int4 ) Creates an integer key-value pair.

tstore -> text Returns a tvalue, which is basically an
oid-value pair.

typeof( tvalue ) Returns the oid.

tvalue::int4 The integer value.

tvalue::text The text value.

each_int( tstore ) Set of all keys and values where the value
is int4.

each_text( tstore ) Set of all keys and values where the value
is text.

each( tstore ) Set of all keys and values as tvalues.

Some examples:

# select 'text: "a"'::tvalue;
tvalue
----------
text: "a"
(1 row)

# select 'integer: 17'::tvalue;
tvalue
----------
int4: 17
(1 row)

# select each_int( '"a" -> text: "b", "b" -> int: 17'::tstore );
?column? | ?column?
----------+----------
"b" | 17
(1 row)

#select '"a" -> text: "b", "b" -> int: 17'::tstore -> 'a';
?column?
-----------
text: "a"
(1 row)

All comments are welcome. As the project matures, I'm sure other
needed functions will crop up.

--
Johann Oskarsson http://www.2ndquadrant.com/ |[]
PostgreSQL Development, 24x7 Support, Training and Services --+--
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Blog: http://my.opera.com/myrkraverk/blog/