Haller,
The way I have handled this in the past is to attempt the following
insert, followed by an update if the insert doesn't insert any rows:
insert into foo (fooPK, foo2)
select 'valuePK', 'value2'
where not exists (select 'x' from foo where fooPK = 'valuePK')
if number of rows inserted = 0, then the row already exists so do an update
update foo set foo2 = 'value2'
where fooPK = 'valuePK'
Since I don't know what client interface you are using (java, perl, C),
I can't give you exact code for this, but the above should be easily
implemented in any language.
thanks,
--Barry
Haller Christoph wrote:
> Hi all,
> Sorry for bothering you with my stuff for the second time
> but I haven't got any answer within two days and the problem
> appears fundamental, at least to me.
> I have a C application running to deal with meteorological data
> like temperature, precipitation, wind speed, wind direction, ...
> And I mean loads of data like several thousand sets within every
> ten minutes.
>>From time to time it happens the transmitters have delivered wrong data,
> so they send the sets again to be taken as correction.
> The idea is to create a unique index on the timestamp, the location id
> and the measurement id, then when receiving a duplicate key error
> move on to an update command on that specific row.
> But, within PostgreSQL this strategy does not work any longer within
> a chained transaction, because the duplicate key error leads to
> 'abort the whole transaction'.
> What I can do is change from chained transaction to unchained transaction,
> but what I have read in the mailing list so far, the commit operation
> requires loads of cpu time, and I do not have time for this when
> processing thousands of sets.
> I am wondering now whether there is a fundamental design error in
> my strategy.
> Any ideas, suggestions highly appreciated and thanks for reading so far.
> Regards, Christoph
>
> My first message:
> In a C application I want to run several
> insert commands within a chained transaction
> (for faster execution).
>>From time to time there will be an insert command
> causing an
> ERROR: Cannot insert a duplicate key into a unique index
>
> As a result, the whole transaction is aborted and all
> the previous inserts are lost.
> Is there any way to preserve the data
> except working with "autocommit" ?
> What I have in mind particularly is something like
> "Do not abort on duplicate key error".
>
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