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Message Posted: Mon, 06 Jul 2004 @ 00:34:22 GMT
I opened an incident some years ago on a similar topic and then closed it after talking to NCR. The problem is how to detect when the result of a join or concatenation will exceed an NCR size limit, and there are basically three choices:
1. Sum the sizes of the column *definitions* and abort if the sum predicts an overflow.
2. Let the processing proceed and abort if an error is detected during processing.
3. Pre-scan all the objects in the query to compute sizes, pre-execute the join plan using sizes only and abort if a problem is detected.
NCR chose #1 because it's quick, easy and there are no wasted resource issues. #2 was rejected because of the potential for unhappy users where one row could abort a long run, and #3 was rejected because of the huge overhead.
A test case is below with my errors at V2R188.8.131.52. Systems using small row sizes will need to edit the 64K to 32K.
create table t1 (upi integer not null, dat varchar(64000)) unique primary index (upi); create table t2 (upi integer not null, dat varchar(64000)) unique primary index (upi); insert into t1 values(1,'A'); insert into t2 values(1,'B'); select * from t1; select * from t2; select t1.upi, t1.dat, t2.dat from t1 inner join t2 on t1.upi = t2.upi; --Error 3577: Row size or Sort Key size overflow. select t1.upi, t1.dat || t2.dat from t1 inner join t2 on t1.upi = t2.upi; --Error 3798: A column or character expression is larger than the max size. select t1.upi, trim(t1.dat) || trim(t2.dat) from t1 inner join t2 on t1.upi = t2.upi; --Error 3798: A column or character expression is larger than the max size.
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