Horton

Re: [Proposal] Global temporary tables

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: Prabhat Sahu <prabhat.sahu@enterprisedb.com>
Cc: 曾文旌(义从) <wenjing.zwj@alibaba-inc.com>, tushar <tushar.ahuja@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Konstantin Knizhnik <k.knizhnik@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, 蔡松露(子嘉) <zijia@taobao.com>, "Cai, Le" <le.cai@alibaba-inc.com>, 萧少聪(铁庵) <shaocong.xsc@alibaba-inc.com>
Date: 2020-03-25T12:57:05Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. PageAddItemExtended(): Add LP_UNUSED assertion.

  2. Remove temporary files after backend crash

  3. Fix comment in indexing.c

  4. Fix failure to ignore leftover temp tables after a server crash.

st 25. 3. 2020 v 13:53 odesílatel Prabhat Sahu <
prabhat.sahu@enterprisedb.com> napsal:

> Hi All,
>
> Please check the behavior of GTT  having column with "SERIAL" datatype and
> column with default value as "SEQUENCE" as below:
>
>
> *Session1:*postgres=# create sequence gtt_c3_seq;
> CREATE SEQUENCE
> postgres=# create global temporary table gtt(c1 int, c2 serial, c3 int
> default nextval('gtt_c3_seq') not null) on commit preserve rows;
> CREATE TABLE
>
> -- Structure of column c2 and c3 are similar:
> postgres=# \d+ gtt
>                                                 Table "public.gtt"
>  Column |  Type   | Collation | Nullable |             Default
> | Storage | Stats target | Description
>
> --------+---------+-----------+----------+---------------------------------+---------+--------------+-------------
>  c1     | integer |           |          |
> | plain   |              |
>  c2     | integer |           | not null | nextval('gtt_c2_seq'::regclass)
> | plain   |              |
>  c3     | integer |           | not null | nextval('gtt_c3_seq'::regclass)
> | plain   |              |
> Access method: heap
> Options: on_commit_delete_rows=false
>
> postgres=# insert into gtt select generate_series(1,3);
> INSERT 0 3
> postgres=# select * from gtt;
>  c1 | c2 | c3
> ----+----+----
>   1 |  1 |  1
>   2 |  2 |  2
>   3 |  3 |  3
> (3 rows)
>
>
> *Session2:*postgres=# insert into gtt select generate_series(1,3);
> INSERT 0 3
> postgres=# select * from gtt;
>  c1 | c2 | c3
> ----+----+----
>   1 |  1 |  4
>   2 |  2 |  5
>   3 |  3 |  6
> (3 rows)
>
> Kindly let me know, Is this behavior expected?
>

It is interesting side effect - theoretically it  is not important, because
sequence ensure just unique values - so values are not important.

You created classic shared sequence so the behave is correct and expected.

Pavel


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