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Cheers Tom.
I'll note that down under the section '...things to note should the
server crash...' - just under the note that says '...get a UPS...'
On Tue, 2008-04-15 at 10:58 -0400, Tom Lane wrote:
> Steve T <steve@[EMAIL PROTECTED]
> writes:
> > I have a set of claims tables that cover the claim itself, the
customer,
> > contact points etc. Yesterday there was a power failure and the server
> > suffered an immediate power outage. When the server came back,
> > everything seemed fine, apart from the fact that the claim related
> > sequences had all jumped and left a gap of 33 (last was 52 before
power
> > failure, next one allocated after power failure 85). This seems
> > consistent across all the tables related to the claim (it may be
across
> > the tables in the database - I haven't checked all of them as yet).
>
> > Does this sound feasible and if so, what is the cause?
>
> Yeah, this is intentional behavior designed to reduce the amount of disk
> write traffic generated by nextval()s. From a standing start, a
> nextval() actually advances the sequence 33 times (1 + SEQ_LOG_VALS),
> so that the next 32 nextval()s won't need to generate their own WAL
> records. I guess you must have crashed before that first nextval()
> was able to commit its result into the database ...
>
> regards, tom lane
Steve Tucknott
ReTSol Ltd
DDI: 01323 488548
Mobile: 0773 671 5772
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Cheers Tom.<BR>
I'll note that down under the section '...things to note should the server
crash...' - just under the note that says '...get a UPS...'<BR>
<BR>
On Tue, 2008-04-15 at 10:58 -0400, Tom Lane wrote:
<BLOCKQUOTE TYPE=CITE>
<PRE>
<FONT COLOR="#000000">Steve T <<A
HREF="mailto:steve@[EMAIL PROTECTED]
">steve@[EMAIL PROTECTED]
>> writes:</FONT>
<FONT COLOR="#000000">> I have a set of claims tables that cover the
claim itself, the customer,</FONT>
<FONT COLOR="#000000">> contact points etc. Yesterday there was a power
failure and the server</FONT>
<FONT COLOR="#000000">> suffered an immediate power outage. When the
server came back,</FONT>
<FONT COLOR="#000000">> everything seemed fine, apart from the fact
that the claim related</FONT>
<FONT COLOR="#000000">> sequences had all jumped and left a gap of 33
(last was 52 before power</FONT>
<FONT COLOR="#000000">> failure, next one allocated after power failure
85). This seems</FONT>
<FONT COLOR="#000000">> consistent across all the tables related to the
claim (it may be across</FONT>
<FONT COLOR="#000000">> the tables in the database - I haven't
checked all of them as yet).</FONT>
<FONT COLOR="#000000">> Does this sound feasible and if so, what is the
cause?</FONT>
<FONT COLOR="#000000">Yeah, this is intentional behavior designed to
reduce the amount of disk</FONT>
<FONT COLOR="#000000">write traffic generated by nextval()s. From a
standing start, a</FONT>
<FONT COLOR="#000000">nextval() actually advances the sequence 33 times (1
+ SEQ_LOG_VALS),</FONT>
<FONT COLOR="#000000">so that the next 32 nextval()s won't need to
generate their own WAL</FONT>
<FONT COLOR="#000000">records. I guess you must have crashed before that
first nextval()</FONT>
<FONT COLOR="#000000">was able to commit its result into the database
...</FONT>
<FONT COLOR="#000000"> regards, tom lane</FONT>
</PRE>
</BLOCKQUOTE>
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<BR>
<B><I><FONT COLOR="#003366">Steve Tucknott</FONT></I></B><BR>
<B><I><FONT COLOR="#ff0000">R</FONT></I></B><B><I><FONT
COLOR="#ff6600">e</FONT></I></B><B><I><FONT
COLOR="#ffcc00">TS</FONT></I></B><B><I><FONT
COLOR="#ff6600">o</FONT></I></B><B><I><FONT COLOR="#ff0000">l
</FONT></I></B><B><I><FONT COLOR="#800000">Ltd</FONT></I></B><BR>
<BR>
<B><I><FONT
COLOR="#003366">DDI: 01323
488548</FONT></I></B><BR>
<B><I><FONT COLOR="#003366">Mobile: 0773 671
5772</FONT></I></B>
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