Re: [Postgres-xc-developers] Issues with Sequences with negative increments

[鈴木 幸市 <ko...@in...>]

I'm afraid the cause is not only by gym.   If min_value is not specified (or specified as "invalid" value), gtm assigns -0x7ffffffffffffffeLL as the minimum value of the sequence (see gtm_seq.[ch]).    So I suspect that minimum value will be specified by DDL in the coordinator.

You fix is very welcome.

GTM in the current master has a backup feature which dumps next restore point of gxid and each sequence to gtm.control.   I hope this helps tests to some extent.

Regards;
---
Koichi Suzuki



On 2013/04/22, at 8:32, Michael Paquier <mic...@gm...> wrote:

> 
> 
> 
> On Mon, Apr 22, 2013 at 3:57 AM, Nikhil Sontakke <ni...@st...> wrote:
> Hi all, 
> 
> Consider the following:
> 
> create sequence seqname increment by -2;
> select nextval('seqname');
> ERROR:  GTM error, could not obtain sequence value
> 
> The above should have returned -1.
> 
> ISTM, the sequence fetching logic on the backend side has been coded entirely with the assumption that sequences can never have negative values. So a less than 0 value returned from get_next() is assumed to be a problem! That's completely wrong. We need to deal with this properly. I will submit a patch for this when I get some time soon. 
> Adding a regression test in xc_sequence.sql would also be good to cover this case as this is caused by xc-only code.
> -- 
> Michael
> ------------------------------------------------------------------------------
> Precog is a next-generation analytics platform capable of advanced
> analytics on semi-structured data. The platform includes APIs for building
> apps and a phenomenal toolset for data science. Developers can use
> our toolset for easy data analysis & visualization. Get a free account!
> http://www2.precog.com/precogplatform/slashdotnewsletter_______________________________________________
> Postgres-xc-developers mailing list
> Pos...@li...
> https://lists.sourceforge.net/lists/listinfo/postgres-xc-developers