Oracle Blockchain Tables With Oracle Database 20c/21c the new feature Oracle Blockchain Tables has been introduced. Blockchain Tables enable Oracle Database users to create tamper-resistant data management without distributing a ledger across multiple parties. Database security can be improved by using Blockchain Tables to avoid user fraud and administrator fraud as well. One of the main characteristics of Oracle Blockchain…
By Mouhamadou Diaw In an Oracle 20c Data Guard environment with a broker configured we can have following files called client-side broker files -The observer configuration file : observer.ora -The observer log file -The observer runtime datafile: fsfo.dat -The fast-start failover callout scripts (new feature in Oracle 20c) Before Oracle 20c, there was no default location for these files. Starting…
By Franck Pachot . This is a demo about Oracle ACFS snapshots, and how to understand the used and free space, as displayed by “df”, when there are modifications in the base parent or the snapshot children. The important concept to understand is that, when you take a snapshot, any modification to the child or parent will [grid@cloud ~]$ asmcmd…
By Mouhamadou Diaw When dealing with cascading or far sync in a Data Guard environment, it is important to understand how to configure the RedoRoutes property. By default, a primary database sends redo to each transport destination that is configured in the destination. We can create more complex transport topology, depending of our environment, using the RedoRoutes property. Basically the…
By Franck Pachot . Sorting data is an expensive operation and many queries declare an ORDER BY. To avoid the sort operation you can build an index as it maintains a sorted structure. This helps with Top-N queries as you don’t have to read all rows but only those from a range of index entries. However, indexes are sorted by…
By Franck Pachot . Advocates of NoSQL can query their structures without having to read a data model first. And without writing long table join clauses. They store and query a hierarchical structure without the need to follow relationships, and without the need to join tables on a foreign key name, in order to get a caption or description from…
By Franck Pachot . This post is part of a series of small examples of recent features. I’m running this in the Oracle 20c preview in the Oracle Cloud. I’ll show a very basic example of “Row Pattern Recognition” (the MATCH_RECOGNIZE clause in a SELECT which is documented as “row pattern matching in native SQL” feature by Oracle”). You may…
By Franck Pachot . This post is part of a series of small examples of recent features. I’m running this in the Oracle 20c preview in the Oracle Cloud. I have created a few tables in the previous post with a mini-snowflake scheme: a fact table CASES with the covid-19 cases per country and day. And a dimension hierarchy for…
By Franck Pachot . This post is the first one from a series of small examples on recent Oracle features. My goal is to present them to people outside of Oracle and relational databases usage, maybe some NoSQL players. And this is why the title is “select from a flat-file” rather than “Inline External Tables”. In my opinion, the names…
By Mouhamadou Diaw A far sync instance is like a standby instance as it can receive redo from the primary database and can ship that redo to other members of the Data Guard configuration. But unlike a physical standby instance, a far sync instance does not contain any datafiles and then can not be open for access. A far sync…
By Franck Pachot . In a previous post https://www.dbi-services.com/blog/awr-dont-store-explain-plan-predicates/ I explained this limitation in gathering filter and access predicates by Statspack and then AWR because of old bugs about reverse parsing of predicates. Oracle listens to its customers through support (enhancement requests), though the community (votes on database ideas), and through the product managers who participate in User Groups and…
By Mouhamadou Diaw With Oracle 20c, the non-multitenant architecture is no longer supported. So, people will have to migrate their databases to container if they want to use Oracle 20c. There are many methods to transform a non-cdb database to a pluggable one. -Datapump -Full Trabsportable Tablespaces -Plugging non-cdb database , upgrade the plugged database and then convert -Upgrading the…
