Horton

Re: [Proposal] Global temporary tables

曾文旌 (义从) <wenjing.zwj@alibaba-inc.com>

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From: wjzeng <wenjing.zwj@alibaba-inc.com>
To: Prabhat Sahu <prabhat.sahu@enterprisedb.com>, Pavel Stehule <pavel.stehule@gmail.com>
Cc: 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: 2020-03-26T03:15:08Z
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.


> 2020年3月25日 下午8:52，Prabhat Sahu <prabhat.sahu@enterprisedb.com> 写道：
> 
> 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?
> 
> -- 

postgres=# \d+
                                   List of relations
 Schema |    Name    |   Type   |    Owner    | Persistence |    Size    | Description 
--------+------------+----------+-------------+-------------+------------+-------------
 public | gtt        | table    | wenjing.zwj | session     | 8192 bytes | 
 public | gtt_c2_seq | sequence | wenjing.zwj | session     | 8192 bytes | 
 public | gtt_c3_seq | sequence | wenjing.zwj | permanent   | 8192 bytes | 
(3 rows)

This is expected.
GTT'sequence is the same as GTT, so gtt_c2_seq is independent of each sessions.
gtt_c3_seq is a classic sequence.



Wenjing


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