Обсуждение: Sequence name length

Hi,

Just a quick one on the length of the name of a sequence.

I have some table with long(ish) names like :     eselect_maincategory
The primary key is named :     maincat_id

When I create the table the sequence sql  looks like     
nextval('"eselect_maincategory_maincat_id_seq"'::text)

However the sequence created is named :     
eselect_maincategory_maincat_id     ( the '_seq' is lopped off )

This looke like a max of 31 characters.

Is a sequence name length limited to 31 characters or is it the tool I'm 
using - phpPgAdmin, I wonder ?

Your time and thoughts are very much appreciated.
Thank you.
Rudi Starcevic.

Hi Rudi,

Unless you redefine it before compiling, postgres has a built-in limit of 31
characters for names.  Increasing this has a performance penalty, but it
might happen for 7.3 due to some improvements in the performance area.

BTW, the best way to do a sequence primary key is lik ethis:

create table blah (maincat_id SERIAL
);

Chris

> -----Original Message-----
> From: pgsql-sql-owner@postgresql.org
> [mailto:pgsql-sql-owner@postgresql.org]On Behalf Of Rudi Starcevic
> Sent: Wednesday, 17 July 2002 10:39 AM
> To: pgsql-sql@postgresql.org
> Subject: [SQL] Sequence name length
>
>
> Hi,
>
> Just a quick one on the length of the name of a sequence.
>
> I have some table with long(ish) names like :     eselect_maincategory
> The primary key is named :     maincat_id
>
> When I create the table the sequence sql  looks like
> nextval('"eselect_maincategory_maincat_id_seq"'::text)
>
> However the sequence created is named :
> eselect_maincategory_maincat_id     ( the '_seq' is lopped off )
>
> This looke like a max of 31 characters.
>
> Is a sequence name length limited to 31 characters or is it the tool I'm
> using - phpPgAdmin, I wonder ?
>
> Your time and thoughts are very much appreciated.
> Thank you.
> Rudi Starcevic.
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org
>

Rudi Starcevic <rudi@oasis.net.au> writes:
> Just a quick one on the length of the name of a sequence.
> ...
> However the sequence created is named :     
> eselect_maincategory_maincat_id     ( the '_seq' is lopped off )

What version are you running?  Anything recent will keep the '_seq'
and lop elsewhere.

> This looke like a max of 31 characters.

Yeah, the default NAMEDATALEN is 32, allowing for 31 chars plus a
terminating null.  You can build a private version with larger
NAMEDATALEN, and there are recurring discussions about increasing
the default length.
        regards, tom lane

> > However the sequence created is named :
> > eselect_maincategory_maincat_id     ( the '_seq' is lopped off )
>
> What version are you running?  Anything recent will keep the '_seq'
> and lop elsewhere.

Not if he's manually creating a sequence name that's too long - it will just
truncate it methinks...

Chris

Hi Tom,

Here is the output from 'select version()'

PostgreSQL 7.2 on i686-pc-linux-gnu, compiled by GCC 2.95.2

Cheers
Rudi.

Tom Lane wrote:

>Rudi Starcevic <rudi@oasis.net.au> writes:
>  
>
>>Just a quick one on the length of the name of a sequence.
>>...
>>However the sequence created is named :     
>>eselect_maincategory_maincat_id     ( the '_seq' is lopped off )
>>    
>>
>
>What version are you running?  Anything recent will keep the '_seq'
>and lop elsewhere.
>
>  
>
>>This looke like a max of 31 characters.
>>    
>>
>
>Yeah, the default NAMEDATALEN is 32, allowing for 31 chars plus a
>terminating null.  You can build a private version with larger
>NAMEDATALEN, and there are recurring discussions about increasing
>the default length.
>
>            regards, tom lane
>
>  
>