Re: obtaining ARRAY position for a given match

2009/11/19 Scott Bailey <artacus(at)comcast(dot)net>:
> Pedro Doria Meunier wrote:
>>
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>> Hi,
>>
>> I'm trying to get the array position for a given match as thus:
>>
>> This gets me the record for a given match:
>> SELECT *  FROM garmin_units WHERE 'L' = ANY (protocol_tag);
>>
>> Ok. so far so good...
>> But what about getting the array position at which 'L' is stored?
>>
>> Searching the Postgresql docs gives me no answer... :(
>> Am I on a wild goose chase?
>>
>> Any insight highly appreciated ;)
>>
>> BR,
>> Pedro Doria Meunier.
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>
> I wrote this a while ago. If you are on 8.4 use unnest instead. And if you
> are searching thru really big arrays, use plpgsql so you can terminate when
> you find a match.
>
> CREATE OR REPLACE FUNCTION idx(text[], text)
> RETURNS int AS
> $$
> SELECT MIN(CASE WHEN $1[i] = $2 THEN i
> ELSE NULL END)::int
> FROM generate_series(array_lower($1, 1),
> array_upper($1, 1)) i;
> $$
> LANGUAGE 'sql' IMMUTABLE STRICT;
>

Hello

it should be little bit more effective:

CREATE OR REPLACE FUNCTION idx(anyarray, anyelement)
RETURNS int AS $$
SELECT i
FROM generate_series(array_lover($1,1),array_upper($1,1)) g(i)
WHERE $1[i] = $2
UNION ALL
SELECT 0 -- return 0 as not found
LIMIT 1; -- stop after first match
$$ LANGUAGE sql;

Regards
Pavel Stehule

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