Re: Help on Procedure running external function

From: Zac <zaccheob(at)inwind(dot)it>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: Help on Procedure running external function
Date: 2005-07-05 11:47:24
Message-ID: dads28$289m$1@news.hub.org
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I think you should use 'FOR UPDATE' clause in your first "select":

select into vnrBon maxnrbon+1 from MagMaxNrBon where magazie =
dsgroup.magazie_implicita_lansare FOR UPDATE;

In this way you lock the rows eventually returned and no one can update
them (or select them "for update") until your transaction finished.

Is this good for you?

However IMHO you should think your procedures to use sequences...

> 1. the function get_me_next_number is runing from this procedure (same
> trans) but it's an external one ...
> 2. the second solution I'am using now (using temp a table to store each
> maxnrdoc value - but the temp table give me sometimes a relation with
> OID ##### does not exist - problem that I can only solve by using
> only execute - but I don't think I can ...?! :))
> here is the example:
>
>
> create temp table MagMaxNrBon
> (
> magazie varchar(5),
> MaxNrBon int8,
> CONSTRAINT temp_magbon_pkey PRIMARY KEY (magazie)
> );
> ...
>
> select into vnrBon maxnrbon+1 from MagMaxNrBon where magazie =
> dsgroup.magazie_implicita_lansare;
> if vnrbon is null
> then
> select into vNrBon o_gen_calc_nr_doc from o_gen_calc_nr_doc('BC'
> ,vEmitent,dsgroup.magazie_implicita_lansare,dsMasterBon.dataBon);
> insert into MagMaxNrBon values
> (dsgroup.magazie_implicita_lansare,vNrBon);
> else
> update MagMaxNrBon set maxnrbon=vNrBon where magazie =
> dsgroup.magazie_implicita_lansare;
> end if;
> ...
>
> and in this way vNrBon is correct one ... I will try to use oly execute
> on insert,update and select on temp table MagMaxNrBon ....
> (o_gen_calc_nr_doc is the "get_me_next_number" function)
>
> thank you,
> Adria Din
>
>
> On Mon, 04 Jul 2005 17:27:20 +0200, Zac <zaccheob(at)inwind(dot)it> wrote:
>
>> Din Adrian wrote:
>>
>>> Yes , I know what sequence is, but our procedure for generating
>>> doc numbers is v. big and has manny (4) parameters and we did'nt
>>> use sequence in it for this reason ....
>>> any other advice ?
>>
>> I think there is no way to have any information about non committed
>> transactions.
>> I don't know if I understand well your problem but from what I see
>> "get_me_next_number" function runs in a different transaction (Why?
>> Is it an externale procedure that make its own connection to the
>> DB?)), otherwise it would see the new inserted number. The better
>> solution is to run "get_me_next_number" in the same transaction.
>> Another solution (not so good but should work) is to generate by
>> yourself the number (as you do) and lock the table until you end to
>> prevent others inserting documents.
>> I hope this helps you.
>> Bye
>>
>>> thak you,
>>> Adi
>>> On Mon, 04 Jul 2005 14:47:16 +0200, Zac <zaccheob(at)inwind(dot)it> wrote:
>>>
>>>> Din Adrian wrote:
>>>>
>>>>> Hello,
>>>>> I have a 'big' problem:
>>>>> I am trying to run from a procedure a function witch generate a
>>>>> new document number (max from table +1 ) and after to insert a
>>>>> document with this number, but the function returns me the same
>>>>> number each time because the tranzaction is not finished and the
>>>>> inserts are not commited and of course the next document number
>>>>> is the same.
>>>>> ...
>>>>> for ...
>>>>> loop
>>>>> nr=get_me_next_number(params);
>>>>> insert into table values (nr,...)
>>>>> end loop
>>>>> ...
>>>>> ...
>>>>> error inserting in table .. primary_key nr .....
>>>>> Is any way in making the external function to 'know' that I
>>>>> inserted another row but this insert is in a tranzaction that is
>>>>> not finish yet ? ar onother solution ?
>>>>> for now I 'solved' by asking for a nr once and generate myself
>>>>> next number (+1) but this is not a correct solution (in this
>>>>> time somebody else could insert a document with the same nr as
>>>>> the procedure )
>>>>> thank you,
>>>>> Adi
>>>>>
>>>> I think the best solution is to use a sequence, not "select max(id)
>>>> +1 from table". Look here:
>>>> http://www.postgresql.org/docs/8.0/interactive/sql-createsequence.html
>>>> http://www.postgresql.org/docs/8.0/interactive/functions-sequence.html
>>>> Bye
>>>>
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>>>>
>>>
>>
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>>
>> http://www.postgresql.org/docs/faq
>>
>
>
>

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