Re: [Proposal] Global temporary tables

From: Prabhat Sahu <prabhat(dot)sahu(at)enterprisedb(dot)com>
To: 曾文旌 <wenjing(dot)zwj(at)alibaba-inc(dot)com>
Cc: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, tushar <tushar(dot)ahuja(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, 蔡松露(子嘉) <zijia(at)taobao(dot)com>, "Cai, Le" <le(dot)cai(at)alibaba-inc(dot)com>
Subject: Re: [Proposal] Global temporary tables
Date: 2020-04-27 13:48:04
Message-ID: CANEvxPoWTnWvLeXsjPiCmEsUZpCgv8aQ7FU1DVoW2i49+8m5+g@mail.gmail.com
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Thanks Wenjing, for the fix patch for previous issues.
I have verified the issues, now those fix look good to me.
But the below error message is confusing(for gtt2).

postgres=# drop table gtt1;
ERROR: cannot drop global temp table gtt1 when other backend attached it.

postgres=# drop table gtt2;
ERROR: cannot drop index idx2 on global temp table gtt2 when other backend
attached it.

I feel the above error message shown for "DROP TABLE gtt2;" is a bit
confusing(looks similar to DROP INDEX gtt2;).
If possible, can we keep the error message simple as "ERROR: cannot drop
global temp table gtt2 when other backend attached it."?
I mean, without giving extra information for the index attached to that GTT.

On Mon, Apr 27, 2020 at 5:34 PM 曾文旌 <wenjing(dot)zwj(at)alibaba-inc(dot)com> wrote:

>
>
> 2020年4月27日 下午5:26,Prabhat Sahu <prabhat(dot)sahu(at)enterprisedb(dot)com> 写道:
>
> Hi Wenjing,
>
> Please check the below scenario shows different error message with "DROP
> TABLE gtt;" for gtt with and without index.
>
> *-- Session1:*postgres=# create global temporary table gtt1 (c1 int);
> CREATE TABLE
> postgres=# create global temporary table gtt2 (c1 int);
> CREATE TABLE
> postgres=# create index idx2 on gtt2(c1);
> CREATE INDEX
>
>
> *-- Session2:*postgres=# drop table gtt1;
> ERROR: can not drop relation gtt1 when other backend attached this global
> temp table
> postgres=# drop table gtt2;
> ERROR: can not drop index gtt2 when other backend attached this global
> temp table.
>
> For DROP GTT, we need to drop the index on the table first.
> So the indexes on the GTT are checked first.
> But the error message needs to be fixed.
> Fixed in v32
>
>
> wenjing
>
>
>
>
>
> --
>
> With Regards,
> Prabhat Kumar Sahu
> EnterpriseDB: http://www.enterprisedb.com
>
>
>

--

With Regards,
Prabhat Kumar Sahu
EnterpriseDB: http://www.enterprisedb.com

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