Re: Temporary table visibility

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От Tom Lane
Тема Re: Temporary table visibility
Дата
Msg-id 1325.1138205260@sss.pgh.pa.us
обсуждение исходный текст
Ответ на Re: Temporary table visibility  (Jaime Casanova <systemguards@gmail.com>)
Ответы Re: Temporary table visibility  (Jaime Casanova <systemguards@gmail.com>)
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Jaime Casanova <systemguards@gmail.com> writes:
> On 1/25/06, James Croft <james.croft@lumison.net> wrote:
>> How can I determine if one of the above relations is a temporary
>> table in the current session (one of them, the first in ns 2200, is a
>> normal permanent table)?

> SELECT n.nspname as "Schema", c.relname as "Name",
>   CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'i'
> THEN '�ndex' WHEN 'S' THEN 'sequence' WHEN 's' THEN 'special' END as
> "Type",
>   r.rolname as "Owner"
> FROM pg_catalog.pg_class c
>      LEFT JOIN pg_catalog.pg_roles r ON r.oid = c.relowner
>      LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
> WHERE c.relkind IN ('r','v','S','')
>       AND n.nspname LIKE 'pg_temp%'
>       AND pg_catalog.pg_table_is_visible(c.oid);

Close, but you really ought to escape the _ to avoid it being a LIKE
wildcard.  I'd tend to use a regex instead since _ isn't a wildcard
in regex patterns.  So the essential part of this is something like

    select relname
    from pg_catalog.pg_class c
         join pg_catalog.pg_namespace n on n.oid = c.relnamespace
    where nspname ~ '^pg_temp_'
         and pg_catalog.pg_table_is_visible(c.oid);

The test on the namespace name tells you it's temp (yes, this is a
legit way to do it, it's the same way the backend decides it's a
temp namespace) and the test on visibility is an easy way to see if
it's your temp namespace or someone else's.

            regards, tom lane

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