Can ARRAY( ... ) generate text[][]?

["J. Greg Davidson" <greg@xxxxxxxxxxx>]

Hi fellow PostgreSQL hackers!

I tried to write an SQL glue function to turn an array
of alternating key/value pairs into an array of arrays
and got the message

ERROR:  42704: could not find array type for data type text[]

-- BEGIN CODE

-- Here's a simplified example:

CREATE OR REPLACE
FUNCTION text__(variadic text[]) RETURNS text[][] AS $$
SELECT ARRAY(
      SELECT ARRAY[ $1[i], $1[i+1] ] 
      FROM generate_series(1, array_upper($1,1), 2) i
)
$$ LANGUAGE sql;

-- Here's what I really wanted:

CREATE OR REPLACE
FUNCTION xpath_(text, xml, variadic text[]) RETURNS xml AS $$
	SELECT ( xpath($1,$2,ARRAY(
      SELECT ARRAY[ $3[i], $3[i+1] ] 
      FROM generate_series(1, array_upper($3,1), 2) i
	)	)	)[1]::xml
$$ LANGUAGE sql;

-- END CODE

Is there any decent way to do this in SQL, or do I need
to write it in a procedural language?

Thanks,

_Greg

J. Greg Davidson


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