redefinition error
Here’s a note about a data error generated by using (possibly mis-using) the dbms_redefinition package (jump to conclusion). The original code to demonstrate the problem comes from a note on the...
View ArticleLag/Lead slow
This note is about a surprising performance difference between the lead() and lag() analytic functions (which31 turns out to be due to the behaviour of the nth_value() function) when the option to...
View ArticleJoin View delete
I’ve written a couple of notes about deleting from join views and (ultimately) the fact that if you have muliple key-preserved tables in join view then the first key preserved table in the from clause...
View Articledrop t/s bug
A recent thread on the MOS database admin forum (needs an account) demonstrated a number of little issues with bugs, debugging, complex syntax, and the never-ending list of “not quite complete” code...
View ArticleEncryption oddity
Here’s a strange problem (with possible workaround) that appeared in a thread on the Oracle developer forum a couple of days ago. It looks like the sort of problem that might be a memory overflow...
View ArticleCase Study
A recent post on the Oracle SQL and PL/SQL forum posted the following query with a complaint that it produced the wrong results: select count(*) from all_synonyms left join all_objects b on...
View ArticleDescending max()
I’ve written a few notes about problems with “descending” indexes in the past (the word is in quotes because it’s not the index that’s defined as descending, it’s a proper subset of the columns of the...
View ArticleDescending Bug
This is another example of defects in the code to handle descending columns in indexes, with the added feature that the problem is addressed somewhere between 19.4 and 19.10 (it’s present in 19.3,...
View ArticleNOT IN bug
Some years ago I wrote a note describing how, with a query using identical literal values in the predicate, the optimizer was able to produce exactly the same plan body with exactly the same Predicate...
View ArticleConsistent?
Here’s a cut-n-paste from a simple SQL*Plus session running under 19.11.0.0 (23.4 produces the same effects): SQL> drop table t purge; Table dropped. SQL> create table t (id number, val number)...
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