Indexes are separate data structures that provide alternate pathways to finding data. They can and do generally speed up the processing of queries and other DML commands, like the INSERT, UPDATE, REPLACE INTO, and DELETE statements. Indexes are also called fast access paths.
Oracle is celebrating the Oracle Community by having us developers nominate and vote forOracle Database Developer Choice Awards to our fellow developers in five database development technologies:SQL, PL/SQL, ORDS, APEX, Db-DesignThe nomination period is over and it has been possible to vote since September 15th.
Have you ever wondered how to leverage substitution variables in anonymous block programs? There are several tricks that you can use beyond passing numeric and string values to local variable. The generic default appears to take a number unless you cast it as a string but that’s not really the whole story. The first two are standard examples of how to use numeric and string substitution values.
The following accept a numeric substitution value:
Using an Oracle object type’s instance in a query is a powerful capability. Unfortunately, Oracle’s SQL syntax doesn’t make it immediately obvious how to do it. Most get far enough to put it in a runtime view (a subquery in the FROM clause), but then they get errors like this:
Rounding amounts may lead to rounding-issues, I have written how this may be resolved in a previous blogpost using some analytic functions. Playing around a little bit, I also came up with a method to resolve the rounding difference with the MODEL clause.
Dividing a certain amount over several rows can be quite tricky, simply rounding can lead to differences. Let me try to explain what I mean. When you need to divide 100 by 3, the answer is 33.333333333333 (and a lot more threes). Money only goes to cents, so if each one gets 33.33, there is a cent missing. (3 times 33.33 equals 99.99) To solve this cent-problem, we decide that the difference should be added (or subtracted) on the last row.
I've been playing around with MATCH_RECOGNIZE - the data pattern matching extension to SELECT that was introduced in version 12. Most examples I've seen have used the default AFTER MATCH SKIP PAST LAST ROW as most often the logic dictates, that when we have found a match in a group of rows, we want to search for further matches after those rows to avoid unwanted "double" matches. But can there be uses where we want overlapping or even nested matches? Well, I found at least one case where I think it makes perfect sense...
In the August 2015 issue of Scientific American, I came across an article titled "Planet Hard Drive", a "thought experiment" arguing that we can think of Earth as a kind of "hard drive" and "although Earth has an enormous capacity to store information, order is still rare....but the growth of order on Earth also stems from the production of cultural information."