One Sequence for all tables or one Sequence for each table?

[Janning Vygen <vygen@xxxxxx>]

Hi,

if you define a SERIAL column postgresql's default is to generate a sequence 
for each SERIAL column (table_column_seq). But you can use one sequence for 
the whole database like this:

CREATE dbsequence;
CREATE TABLE one (
  id int4 NOT NULL DEFAULT nextval('dbseq')
);
CREATE TABLE two (
  id int4 NOT NULL DEFAULT nextval('dbseq')
);

One drawback: You reach the internal end of a sequence faster if you use your 
sequence for all tables. But this can be avoided if you use int8 datatype. 

Are there other drawbacks/benfits using one Sequence for each table or one 
sequence for all tables?

kind regards,
janning

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