** Reply to message from Jan Wieck <JanWieck@Yahoo.com> on Thu, 29 May 2003
20:25:56 -0400
Hi Jan,
Yup, staging tables are probably going to be the answer in this case.
However, my point is, you shouldn't need workarounds for this. (or for the
more general insert on failure update on failure ignore type of logic used in a
lot of import scenarios)
Taking the decision if or not to rollback a transaction (sql error or no) away
from the application, and enforcing it in the dbm, results in kluges,
workarounds, and a generally less robust dbm.
Regards,
Wayne
> Martijn van Oosterhout wrote:
> > On Sun, May 25, 2003 at 10:04:30AM +1000, Wayne Armstrong wrote:
> >
> >> During import of 120 thousand records from an isam file system, 3 say records
> >>fail integrity checks ( files in non-database systems tend not to have
> >>referential integrity implemented on them except at an application level
> >>(meaning not at all :). The desired result is to drop the records failing
> >>integrity checks.
> >
> >
> > Yes, I have that problem too. I actually wrote a script that took an input
> > file and automatically reissued queries that succeeded but got rolled-back.
> > I called it quickloader.pl :)
> >
> > Probably the biggest problem is that you can't use COPY to load the data.
> > I've thought about loading into another table and transferring later but I
> > havn't sorted out the details.
>
> The general idea would be to setup a table that has exactly the same
> structure as the final target table, but with no constraints at all. As
> long as your data passes all input functions you can even COPY it in.
>
> Now you run check queries that show you all tuples in that staging table
> that would fail constraints on the final table. Fix those and you can do
>
> INSERT INTO final SELECT * FROM staging;
>
> If step one fails because of data that doesn't pass the input functions
> of our data types, you have to go through another level of staging with
> a table that has text fields only and move it by explicit casting after
> cleaning up those problems.
>
>
> Jan
>
> --
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