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Re: BUG #5776: Unable to create view with parameter in PL/pgsql

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: "Andrey G(dot)" <andvgal(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #5776: Unable to create view with parameter in PL/pgsql
Date: 2010-12-14 11:19:48
Message-ID: AANLkTin7J-sAHFfGYN0h8sEemiD3FaSvfzymyB4=w9nw@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-bugs
Hello

2010/12/14 Andrey G. <andvgal(at)gmail(dot)com>:
> Pavel,
>
> As far as I'm aware, SETOF return creates whole result in memory, what
> has some implications.
>

it's not true for immutable SQL function - look on EXPLAIN

> My intention was to create a temporary view in session, which can be
> used in other processing. Of course, I've found another solution, but
> creating view with parameter dynamically could be a good feature.
>

It's done - SQL immutable function works exactly like you need.

Regards

Pavel Stehule


> Andrey
>
>
>
> 2010/12/14 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>:
>> Hello
>>
>> View must not has a parameter in PostgreSQL. You can use a SRF function:
>>
>> postgres=# create or replace function parametrized_view(a int)
>>                  returns setof foo as $$
>>                     select * from foo where a = $1;
>>                  $$ language sql immutable;
>> CREATE FUNCTION
>> postgres=# select * from parametrized_view(10);
>>  a
>> ----
>>  10
>> (1 row)
>>
>> postgres=# explain select * from parametrized_view(10);
>>                          QUERY PLAN
>> --------------------------------------------------------------
>>  Index Scan using aa on foo  (cost=0.00..8.27 rows=1 width=4)
>>   Index Cond: (a = 10)
>> (2 rows)
>>
>> Regards
>>
>> Pavel Stehule
>>
>>
>> 2010/12/13 Andrey G. <andvgal(at)gmail(dot)com>:
>>> It seems my original test, which also includes the EXECUTE approach,
>>> has not come to you in full. EXECUTE statement also fails with
>>> parameter: The test is attached in file.
>>>
>>> psql -q < db/db/pgbug_5776.sql
>>> ERROR:  there is no parameter $1
>>> LINE 1: CREATE VIEW v4 AS SELECT * FROM t1 WHERE some_field = $1
>>>                                                               ^
>>> QUERY:  CREATE VIEW v4 AS SELECT * FROM t1 WHERE some_field = $1
>>> CONTEXT:  PL/pgSQL function "bug_create_tmp_view_exec_test" line 3 at
>>> EXECUTE statement
>>>
>>> Andrey
>>>
>>>
>>> 2010/12/13 Robert Haas <robertmhaas(at)gmail(dot)com>
>>>>
>>>> On Tue, Nov 30, 2010 at 4:43 PM, Andrey Galkin <andvgal(at)gmail(dot)com> wrote:
>>>> >
>>>> > The following bug has been logged online:
>>>> >
>>>> > Bug reference:      5776
>>>> > Logged by:          Andrey Galkin
>>>> > Email address:      andvgal(at)gmail(dot)com
>>>> > PostgreSQL version: 9.0.1
>>>> > Operating system:   Debian unstable
>>>> > Description:        Unable to create view with parameter in PL/pgsql
>>>> > Details:
>>>> >
>>>> > Below is simple test case. Perhaps, I'm doing something wrong.
>>>>
>>>> You can accomplish what you're trying to do using EXECUTE.
>>>>
>>>> --
>>>> Robert Haas
>>>> EnterpriseDB: http://www.enterprisedb.com
>>>> The Enterprise PostgreSQL Company
>>>
>>>
>>> --
>>> Sent via pgsql-bugs mailing list (pgsql-bugs(at)postgresql(dot)org)
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>>>
>>>
>>
>

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