From: Andrew Dunstan <andrew@dunslane.net>
To: Sergey Konoplev <gray.ru@gmail.com>
Cc: George Neuner <gneuner2@comcast.net>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: help: function failing
Date: Tue, 07 Oct 2014 17:27:58 -0400
Message-ID: <54345ADE.8030806@dunslane.net> (raw)
In-Reply-To: <CAL_0b1uwhpvPrrtC6ba6E=bBn+euj78VM-qWH+cp3jxrYyskPw@mail.gmail.com>
References: <542DD92A.9000305@comcast.net>
<CAL_0b1uwhpvPrrtC6ba6E=bBn+euj78VM-qWH+cp3jxrYyskPw@mail.gmail.com>
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On 10/07/2014 04:41 PM, Sergey Konoplev wrote:
> On Thu, Oct 2, 2014 at 4:00 PM, George Neuner <gneuner2@comcast.net> wrote:
>> --------------- code ----------------
>> CREATE OR REPLACE FUNCTION gen_random()
>> RETURNS double precision AS
>> $BODY$
>> DECLARE
>> num float8 := 0;
>> den float8 := 281474976710655; -- 0xFFFFFFFFFFFF
>> bytes bytea[6];
>> BEGIN
>> -- get random bytes from crypto module
>> bytes := ext.gen_random_bytes(6);
>>
>> -- assemble a double precision value
>> num := num + get_byte( bytes, 0 );
>> FOR i IN 1..5 LOOP
>> num := num * 256;
>> num := num + get_byte( bytes, i );
>> END LOOP;
>>
>> -- normalize value to range 0.0 .. 1.0
>> RETURN num / den;
>> END;
>> $BODY$
>> LANGUAGE plpgsql VOLATILE;
>> --------------- code ----------------
>>
>> The error is:
>> ERROR: array value must start with "{" or dimension information
>> SQL state: 22P02
>> Context: PL/pgSQL function gen_random() line 8 at assignment
>>
>> which, if I'm counting correctly, is
>> bytes := ext.gen_random_bytes(6);
> Guessing on the name of ext.gen_random_bytes(6) it returns a value
> that is incompatible with bytea[] array representation time from time,
> so take a closer look at ext.gen_random_bytes() first. You can test
> the case using DO block.
>
>> If I comment out that line, it then tells me get_byte() is undefined,
>> which should be impossible because it's built in.
> Feels like somewhere inside ext.gen_random_bytes() you set a
> search_path that allows to see get_byte() and the search_path that was
> set before the gen_random() call doesn't allow it.
>
Why does this code want an array of byteas?
It looks like the code thinks bytea[6] is a declaration of a bytea of
length 6, which of course it is not. Shouldn't it just be declared as:
bytes bytea;
?
Oh, and pgsql-performance is completely the wrong forum for this query.
usage questions should be on pgsql-general.
cheers
andrew
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To: pgsql-performance@postgresql.org
Cc: andrew@dunslane.net, gray.ru@gmail.com, gneuner2@comcast.net
Subject: Re: help: function failing
In-Reply-To: <54345ADE.8030806@dunslane.net>
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