Re: [PERFORM] Auto generate number in Postgres-9.1. - Mailing list pgsql-performance

Hi,

Thanks for your immediate response!!!!

Its working fine when we insert a new row.

But on deletion it's not automatically re-adjusting the id's.

Do I need to create trigger for this??

Regards,
Dinesh Chandra
|Database administrator (Oracle/PostgreSQL)| Cyient Ltd. Noida.


-----Original Message-----
From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of John Gorman
Sent: 20 March, 2017 7:20 PM
To: pgsql-performance@postgresql.org; pgsql-performance-owner@postgresql.org
Subject: Re: [PERFORM] Auto generate number in Postgres-9.1.

Sequences are stored as a separate object in PostgreSQL.

Here in this example table and you can see that rec_id is a sequence number and that the object name is:
whiteboards_rec_id_seq

mydb=> \d whiteboards

                                         Table "public.whiteboards"
    Column     |            Type             |                          Modifiers
---------------+-----------------------------+--------------------------
---------------+-----------------------------+--------------------------
---------------+-----------------------------+----------
 rec_id        | integer                     | not null default nextval('whiteboards_rec_id_seq'::regclass)
 board_name    | character varying(24)       | not null
 board_content | text                        | not null
 updatets      | timestamp without time zone | default now()
Indexes:
    "whiteboards_pkey" PRIMARY KEY, btree (rec_id)

Now I can display the whiteboards_rec_id_seq object

mydb=> \dS whiteboards_rec_id_seq
     Sequence "public.whiteboards_rec_id_seq"
    Column     |  Type   |         Value
---------------+---------+------------------------
 sequence_name | name    | whiteboards_rec_id_seq
 last_value    | bigint  | 12
 start_value   | bigint  | 1
 increment_by  | bigint  | 1
 max_value     | bigint  | 9223372036854775807
 min_value     | bigint  | 1
 cache_value   | bigint  | 1
 log_cnt       | bigint  | 31
 is_cycled     | boolean | f
 is_called     | boolean | t

-----Original Message-----
From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Josh Berkus
Sent: Monday, March 20, 2017 6:43 AM
To: Dinesh Chandra 12108; pgsql-performance-owner@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Auto generate number in Postgres-9.1.

Dinesh,

> I have to add one column  "ID" in postgres table which will generate
> Auto Increment
> <http://www.davidghedini.com/pg/entry/postgresql_auto_increment>ed number .
>
>
>
> Example:
>
> Suppose I have five records and if I insert 1 new record It should
> auto generate 6.

https://www.postgresql.org/docs/9.6/static/sql-createsequence.html
also SERIAL on this page:
https://www.postgresql.org/docs/9.6/static/datatype-numeric.html


>
> If I truncate the same table and then again insert rows should start
> with 1 in "ID" column.

That's not how it works, normally.  I'd suggest adding an ON TRUNCATE trigger to the table.


--
Josh Berkus
Containers & Databases Oh My!


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