Oracle Team

Oracle 12cR2 Optimizer Adaptive Statistics

By Franck Pachot . When 12.1 came out, the major issue we encountered after migration was related to the new adaptive features of the optimizer: automatic reoptimization, SQL Plan Directives and the resulting dynamic sampling. Of course, Oracle product managers(…)

Oracle 12cR2 Long Identifiers

By Franck Pachot . This morning during Gerald Venzl presentation of "What’s New for Developers in the Next Generation of Oracle Database" at Oracle Open World, one feature has been acclaimed by a full room: 12.2 show the end of(…)

Oracle Database 12.2 – PDBaaS

By Franck Pachot . It's official, Larry Ellison made the announcement at first keynote and the database product team at oracle has released the version and the documentation publicly. Oracle Database Exadata Express Cloud Service is the 'Cloud First' environment(…)

Oracle 12cR2 SQL new feature: LISTAGG overflow

By Franck Pachot . LISTAGG was a great feature introduced in 11g: put rows into line with a simple aggregate function. 12cR2 adds an overflow clause to it. What happens when you have so many rows that the LISTAGG(…)

Result cache side effects on number of calls

By Franck Pachot . During the execution of a SQL statement, you cannot guess how many times an operation, a predicate, or a function will be executed. This depends on the execution plan, on some caching at execution, and some(…)

Sharding with PostgreSQL

By Mouhamadou Diaw In this article we are going to talk about sharding in PostgreSQL. What is sharding, Sharding is like partitioning. The difference is that with traditional partioning, partitions are stored in the same database while sharding shards (partitions)(…)

Multitenant thin provisioning: PDB snapshots on ACFS

By Franck Pachot . Database on ACFS is a long story. At first, the main reason for ASM was to bypass a filesystem layer that is not required by the database. ACFS was for the non-database files that had to(…)

Disable Red Hat 7 Transparent Hugepages

Ausgangslage Ein Kunde hat mich kürzlich angefragt, wie am effizientesten alle Kernel Tuning Parameter für Oracle bei Red Hat 7 konfiguriert werden können. Daraus habe ich untersucht welche Möglichkeiten es gibt, ausser dem seit langer Zeit bekannten /etc/sysctl.conf. Bei dieser Analyse(…)

Adaptive Plans and cost of inactive branches

By Franck Pachot . Here are the details about an execution plan screenshot I've tweeted recently because the numbers looked odd. It's not a big problem, or maybe not a problem at all. Just something surprising. I don't like when(…)

Understanding Row Level Security on PostgreSQL

By Mouhamadou Diaw In this article we will talk about a nice feature Row Level Security on PostgreSQL. We are using EDB Postgres (…)