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Thread: Drop only temporary table

Drop only temporary table

From
Durumdara
Date:
Dear PG Masters!

As I experienced I can create normal and temp table with same name.

create table x (kod integer);

CREATE TEMPORARY TABLE x (kod integer);

select tablename from pg_tables where schemaname='public'
 union all
select c.relname from pg_class c
join pg_namespace n on n.oid=c.relnamespace
where  
n.nspname like 'pg_temp%'
and c.relkind = 'r'
and pg_table_is_visible(c.oid);

---

I can see two x tables.

As I see that drop table stmt don't have "temporary" suboption to determine which to need to eliminate - the real or the temporary.

Same thing would happen with other DDL/DML stmts - what is the destination table - the real or the temporary?

"insert into x(kod) values(1)"

So what do you think about this problem?

I want to avoid to remove any real table on resource closing (= dropping of temporary table).
How to I force "drop only temporary"? Prefix, option, etc.

Thanks for your help!

dd

Re: Drop only temporary table

From
Tom Lane
Date:
Durumdara <durumdara@gmail.com> writes:
> As I experienced I can create normal and temp table with same name.

Sure.

> As I see that drop table stmt don't have "temporary" suboption to determine
> which to need to eliminate - the real or the temporary.

Once you've created a temp table, it masks any normal table of the same name
(unless you use a schema-qualified reference to the normal table).

            regards, tom lane

Re: Drop only temporary table

From
Aleksander Alekseev
Date:
You can use schema name as a prefix:

postgres=# \d+
                       List of relations
  Schema   | Name | Type  |  Owner   |    Size    | Description
-----------+------+-------+----------+------------+-------------
 pg_temp_1 | t    | table | postgres | 8192 bytes |
(1 row)

postgres=# drop table pg_temp_1.t;
DROP TABLE

But generally speaking I suggest you generate random names for
temporary tables.

On Fri, 18 Mar 2016 13:47:06 +0100
Durumdara <durumdara@gmail.com> wrote:

> Dear PG Masters!
>
> As I experienced I can create normal and temp table with same name.
>
> create table x (kod integer);
>
> CREATE TEMPORARY TABLE x (kod integer);
>
> select tablename from pg_tables where schemaname='public'
>  union all
> select c.relname from pg_class c
> join pg_namespace n on n.oid=c.relnamespace
> where
> n.nspname like 'pg_temp%'
> and c.relkind = 'r'
> and pg_table_is_visible(c.oid);
>
> ---
>
> I can see two x tables.
>
> As I see that drop table stmt don't have "temporary" suboption to
> determine which to need to eliminate - the real or the temporary.
>
> Same thing would happen with other DDL/DML stmts - what is the
> destination table - the real or the temporary?
>
> "insert into x(kod) values(1)"
>
> So what do you think about this problem?
>
> I want to avoid to remove any real table on resource closing (=
> dropping of temporary table).
> How to I force "drop only temporary"? Prefix, option, etc.
>
> Thanks for your help!
>
> dd



--
Best regards,
Aleksander Alekseev
http://eax.me/

Re: Drop only temporary table

From
Melvin Davidson
Date:

On Fri, Mar 18, 2016 at 9:31 AM, Aleksander Alekseev <a.alekseev@postgrespro.ru> wrote:
You can use schema name as a prefix:

postgres=# \d+
                       List of relations
  Schema   | Name | Type  |  Owner   |    Size    | Description
-----------+------+-------+----------+------------+-------------
 pg_temp_1 | t    | table | postgres | 8192 bytes |
(1 row)

postgres=# drop table pg_temp_1.t;
DROP TABLE

But generally speaking I suggest you generate random names for
temporary tables.

On Fri, 18 Mar 2016 13:47:06 +0100
Durumdara <durumdara@gmail.com> wrote:

> Dear PG Masters!
>
> As I experienced I can create normal and temp table with same name.
>
> create table x (kod integer);
>
> CREATE TEMPORARY TABLE x (kod integer);
>
> select tablename from pg_tables where schemaname='public'
>  union all
> select c.relname from pg_class c
> join pg_namespace n on n.oid=c.relnamespace
> where
> n.nspname like 'pg_temp%'
> and c.relkind = 'r'
> and pg_table_is_visible(c.oid);
>
> ---
>
> I can see two x tables.
>
> As I see that drop table stmt don't have "temporary" suboption to
> determine which to need to eliminate - the real or the temporary.
>
> Same thing would happen with other DDL/DML stmts - what is the
> destination table - the real or the temporary?
>
> "insert into x(kod) values(1)"
>
> So what do you think about this problem?
>
> I want to avoid to remove any real table on resource closing (=
> dropping of temporary table).
> How to I force "drop only temporary"? Prefix, option, etc.
>
> Thanks for your help!
>
> dd



--
Best regards,
Aleksander Alekseev
http://eax.me/


--
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It is not wise to create temp tables with the same name as actual tables.
It is always a good idea to prefix temp tables with something like "tmp_' or "t_';

--
Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

Re: Drop only temporary table

From
"David G. Johnston"
Date:
On Friday, March 18, 2016, Durumdara <durumdara@gmail.com> wrote:

I want to avoid to remove any real table on resource closing (= dropping of temporary table).
How to I force "drop only temporary"? Prefix, option, etc.


If you have to explicitly drop a temporary table you are likely doing something wrong.  When you create the table you tell it when to go away and at that time it will - no need for a drop statement.

David J.