Sometimes you need to add by hand a primary key on a table that initially did not have any constraint. Most of the time you will run into the issue of having duplicate rows, so first we must make sure there are no duplicate rows. Duplicate rows are the rows that have duplicates in the… Read More »
After upgrading my developement Oracle database to 12c I discovered that an old legacy application still under support was no longer working throwing the following Oracle error: After some digging I found the following reported bug: Bug 14575666 In 12.1, the default value for the SQLNET.ALLOWED_LOGON_VERSION parameter has been updated to 11. This means that… Read More »
One of the most annoying things is when some vendor decides that it is a good idea to change some very basic and long time existing basic behaviour. In the new Oracle 12c you are no longer able to create local users the old way as sys: If you try to execute the above the… Read More »
There are times when we need to find which are the tables that depend on a given table. This is useful when cleanup or archiving jobs have to pe performed and the interconnection of constraints is becoming a nuisance. Lucky for us in the case of Oracle database is quite simple to search through all… Read More »
Reinstalling things like Oracle is always a hassle and takes about one day to make it work. Lucky for me I made a full back-up of my old disk when I upgraded to a new laptop. On the new laptop I did a fresh install of Fedora 28. The idea is to migrate my old… Read More »
At some point I discovered GO trying to do very simple and fast code for specific tasks without having to load lots of libraries, deploy application servers or set up complicated frameworks. If you want to build fast very small native micro-services that can be deployed in a docker instance < 10MB Go is the… Read More »
Sometimes we may end up having some application resources competing for the same resource on our Oracle database. This is usually the case when some exclusive resource must be allocated or updated as in the case of database based locking mechanisms. If there are code issues we may end up in a deadlock situation when… Read More »
Sometimes very annoying things can be removed with a simple SQL commands which nobody remembers because is used so rarely. For example when we have to update a database schema and remove a not null constraint on a column. There is a short one liner for it: ALTER TABLE my_table ALTER COLUMN name DROP not… Read More »
It looks like the Microsoft SQL Database Mirroring a feature I used a lot and for which posted a step by step tutorial that proved to be very popular was deprecated by Microsoft. In a news article on Microsoft site the alternative is presented “Basic Availability Groups (Always On Availability Groups)”. I will summarize in… Read More »
DELETE operations are much faster in case we disable constraints. This is because not all foreign keys affected by the DELETE are indexed. We have to detect all the foreign keys that point to the table from where you delete data. The we can create temporary indices to help speed up the delete. STEP 1.… Read More »