failed insert into serial-type row

["Hortschitz, Stefan" <Stefan.Hortschitz@xxxxxxx>]

hi,

 

i’m working with an postgresql-installation on Solaris ("PostgreSQL 7.4.7 on sparc-sun-solaris2.9, compiled by GCC 2.95.3") and I have the following problem:

 

I’m using tables like this:

--------------------------------

CREATE TABLE session.preferences

(

  id serial NOT NULL,

  name varchar(50),

  value varchar(255),

  CONSTRAINT session_preferences_pkey PRIMARY KEY (id)

)

WITHOUT OIDS;

ALTER TABLE session.preferences OWNER TO web;

--------------------------------

 

and sometimes if i'm adding new rows to the table with statements like this:

      insert into (name,value) (‘xy’,’xy’);

the database only returns an ‘duplicate key on primary key’, which should be prevented by the serial-datatype, or? how could it be, that two rows become the same id??

if i execute the insert-statement again it works.

 

the created serial-sequence looks like this:

--------------------------------

CREATE SEQUENCE session.preferences_id_seq

  INCREMENT 1

  MINVALUE 1

  MAXVALUE 9223372036854775807

  START 2487

  CACHE 1;

ALTER TABLE session.preferences_id_seq OWNER TO web;

--------------------------------

 

what can I do against the duplicate-key problem? is it a configuration, sql or operating-system specific problem?

 

with kind regards

stefan