| user_sequences table [message #278675] |
Mon, 05 November 2007 06:32  |
mitthu
Messages: 3
Registered: November 2007
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Junior Member |
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Hi
I am trying the following query:
create sequence s start with 1 increment by 1;
Sequence created.
select s.nextval from dual;
NEXTVAL
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1
select CACHE_SIZE, LAST_NUMBER from user_sequences where sequence_name = 'S';
CACHE_SIZE shows value 20
LAST_NUMBER shows value 21
1 declare
2 begin
3 execute immediate ('alter sequence s increment by 10');
4* end;
PL/SQL procedure successfully completed.
select s.nextval from dual;
NEXTVAL
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11
select CACHE_SIZE, LAST_NUMBER from user_sequences where sequence_name = 'S';
CACHE_SIZE shows value 20
LAST_NUMBER shows value 211
What is the significance of these 2 columns and how do they change?
Thanks
Mitthu
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| Re: user_sequences table [message #278682 is a reply to message #278679] |
Mon, 05 November 2007 06:57  |
JRowbottom
Messages: 5933
Registered: June 2006
Location: Sunny North Yorkshire, ho...
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Senior Member |
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I thought that the cached sequence values were held in memory for general use - I've just run a test on a sequence with a cache of 20 where different sessions have been able to consistently get consecutive values back from the sequence/
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You're right. It appears that they are simply cached for general use. My bad. I should have known though. The general purpose for caching is performance if I'm not mistaken. The bottom line remains though: it is all in the manuals.