 |
 |
Archives of the TeradataForum
Message Posted: Thu, 29 Oct 2015 @ 21:04:24 GMT
| Subj: | | Re: SET vs MULTISET tables with UPI/USI |
| |
| From: | | Anomy Anom |
<-- Anonymously Posted: Thursday, October 29, 2015 16:39 -->
Fred Pluebell wrote:
| | The duplicate row checking is still done, but with a UPI you only have to check at most one row so the overhead is tiny. With NUPI, the
overhead can be substantial even with a USI. | |
| | If you have a SET table with a UPI or USI, then multiple-row operations (e.g. INSERT SELECT or MERGE) will quietly eliminate duplicate rows
, whereas with MULTISET table and UPI or USI, the duplicate key check will cause the operation to fail. For single-row operations (e.g. INSERT
VALUES), SET/MULTISET both give duplicate key error. | |
So to narrow this down - for SET tables with UPI/USI, TD will check only the UPI/USI column(s) for duplicates and entire row (all columns)
checking will not be done ?
Thanks
| |
