The Autonomous Data Warehouse Cloud (ADWC) is a self-configuring, fast, secure and scalable platform for data warehouses. Does this mean we don’t have to take care anymore about performance of our ETL processes? Which performance tips are still important for us, and where can we hand over the responsibility to ADWC? A revised version of an old blog post, with regard to Oracle’s Data Warehouse Cloud solution.
Optimizer statistics are essential for good execution plans and fast performance of the SQL queries. Of course, this is also the case in the Autonomous Data Warehouse Cloud. But the handling of gathering statistics is slightly different from what we know from other Oracle databases.
In Oracle Autonomous Data Warehouse Cloud, External Tables can be used to read files from the cloud-based Object Storage. But take care to do it the official way, otherwise you will see a surprise, but no data.
Global temporary tables (or private temporary tables, if you use Oracle 18c) are a practical feature to be used for SQL queries with multiple steps, for example complex reports in a data warehouse. If you want to use them, some details must be considered.
Direct-Path INSERT is a very efficient way to load data into data warehouse tables. The load performance can even be improved with NOLOGGING on the target table. In Oracle 12c Release 2, this is even possible for Oracle Data Guard environments. But is it a good idea?
In summer time, the nights are very short. For some Data Warehouses, this is the case all year round, but not because of late sunset and early sunrise. The night is not long enough to finish all the ETL jobs. Long-running load jobs that run for several hours are not a seldom situation. Here some tips how this can be avoided.
There are many new extensions for Partitioning in Oracle 12c Release 2 (12.2). One of them is the CREATE TABLE FOR EXCHANGE statement. Some years ago, I wished to have this feature for a particular problem with hidden columns.