David,
Thanks for that. There is always a feeling of relief and frustration when you
learn that a language simply cannot do what you are trying to get it to do.
You mentioned that this could be done by brute force with PL/PGSQL. I do have
this available, but am somewhat unfamiliar with it and am not sure where to
begin. I can answer the two situations you brought up.
1. No, the records do not have to match up with records on the same
table. I created the two temp tables as a way of separating the entries with
the entry reversals, if that makes sense. Now I am trying to reconcile the
tables and take out the appropriate records.
2. It is not possible for a record to be deleted.
As for meta-data, I am not too concerned with that at the moment. I am looking
just to create a monthly "snapshot" report using this data. Because I am
pulling this data from data feeds, I can control any "matching" entries that
would occur after the first of the current month. Thank you for considering
these things in my problem.
That being said, since I am mostly unfamiliar with PL/PGSQL could you (or
anyone) provide an example of a solution? I am playing with loops, but I am
not sure I am on the right path.
Thanks,
Jeff Herman
HVPA, Database Programmer
Phone: 734.973.0137 ext 441
Fax: 734.975.1248
herm...@hvpa.com
-----Original Message-----
From: David Johnston [mailto:pol...@yahoo.com]
Sent: Tuesday, February 21, 2012 2:04 PM
To: 'Andy Colson'; Jeff Herman
Cc: pgsql-general@postgresql.org
Subject: RE: [GENERAL] Combining data from Temp Tables
-----Original Message-----
From: pgsql-general-ow...@postgresql.org
[mailto:pgsql-general-ow...@postgresql.org] On Behalf Of Andy Colson
Sent: Tuesday, February 21, 2012 1:37 PM
To: Jeff Herman
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Combining data from Temp Tables
how about
select date, ln, mbrid, ds, (
select sum(ds) from t2
where t2.date >= t1.date and t2.date <= t1.date + '5 days'::interval
and t1.ln = t2.ln
and t1.mbrid = t2.mbrid)
from t1
That'll give you both the plus and minus (in two different columns), but it
might sum up the same row from table2 multiple times so I'm not sure its
correct.
And I'm not sure the date range is correct.
Another way to look at the same thing:
select date, ln, mbrid, dsplus - dsminus from (
select date, ln, mbrid, ds as dsplus, (
select sum(ds) from t2
where t2.date >= t1.date and t2.date <= t1.date + '5 days'::interval
and t1.ln = t2.ln
and t1.mbrid = t2.mbrid) as dsminus
from t1
) as x
where dsplus - dsminus <> 0
Totally guessing here.
-Andy
-------------------------------------------------------------------
I am pretty certain this cannot be sufficiently solved via a declarative
statement; it requires procedural logic.
For each unmatched record on table 1 you compare all unmatched records on table
2. You pair the first one that matches and exclude the table 2 record from all
future comparisons.
I have done this before but my approach was to load all the unmatched records
into Java and perform the procedural logic there. This can be done in PL/PGSQL
in a brute-force way and then, if performance is unacceptable, you can try to
add efficiencies or farm out the processing to a more full featured programming
language (one having Lists/Maps and/or Iterators).
Two possible situations to consider:
1) Does a record on table 1 (or table 2) ever have to match up with another
record on the same table (i.e., entry reversal)?
2) Is it ever possible for a record to be deleted?
Also consider what kind of meta-data you want to track in order to generate a
proper reconciliation report. One common need is to know what the
reconciliation status looked like at some date in the past. For instance on
the 5th of the month I want to know the exact reconciliation status of my bank
account. To do this I have to ignore any "matching" entries that occurred on
or after the 1st of the current month (like checks clearing).
Again, the situation you are dealing with almost certainly requires a
procedural solution and so pure SQL is not going to work. You need PL/PGSQL
(or some other embedded language) or, if you already have an application server
hooked into the database, a "query-process-update" routine coded and run off
the application server.
David J.
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