In a previous post about enabling large page on Windows Server, I explained that it’s possible to use large pages with Automatic Memory Management (AMM, where sizing if SGA and PGA is automatic with MEMORY_TARGET setting) but possible does not mean that it is recommended. We feel that it’s not a good idea, but are there reasons for it or it’s just our linux backgroud that brings this opinion?
All posts by Franck Pachot
The new ODA X-6 has been announced last month with two smaller configurations and smaller prices: 2S and 2M. Small, but high performance configuration: all SSD, and I/O transfer optimized for Flash with PCIe bus and NVMe protocol. Let’s see how it keeps up with an high OLTP workload. Thanks to Arrow Oracle Authorized Solution Center to let us evaluate performance on their ODA.
The latest DBA Essentials Workshop training I’ve given raised a question about PGA_AGGREGATE_LIMIT. The default depends on PGA_AGGREGATE_TARGET. So how is it calculated in AMM where PGA_AGGREGATE_TARGET is dynamic? Is it also dynamic or is it determined by the value at instance startup only?
This morning I wanted to test a patch (18633374) in the Oracle Cloud Service. The DBaaS was created as an ‘Enterprise Edition Extreme Performance’ which comes with all options, including multitenant option. I applied my patch. My test required to create a new tablespace but it failed with: ORA-65010: maximum number of pluggable databases created
Comparison of NULL can be misleading and it’s even worse for unique constraint validation. Having partial nulls in a composite key can be tricky because the SQL ANSI specification is not very easy to understand, and implementation can depend on the RDBMS. Here is an example with composite unique key and foreign key on Oracle.
We all know what is the multitenant option: a container database (CDB) with multiple user pluggable databases (PDB). This requires Enterprise Edition plus option. But you can use the same architecture without the option and even in Standard Edition: a CDB with only one user PDB. It is called “single-tenant” or “lone PDB”. How do you call this new 12c architecture?
You’ve setup a logical replication, and you trust it. But before the target goes into production, it will be safer to compare source and target. At least count the number of rows. But tables are continuously changing, so how can you compare? Not so difficult thanks to Dbvisit replicate heartbeat table and Oracle flashback query.
In Oracle, when the referenced key is deleted (by delete on parent table, or update on the referenced columns) the child tables(s) are locked to prevent any concurrent insert that may reference the old key. This lock is a big issue on OLTP applications because it’s a TM Share lock, usually reserved for DDL only, and blocking any modification on the child table and blocking some modifications on tables that have a relationship with that…
When you don’t have Enterprise Edition + Diagnostic Pack, you cannot use AWR but you can, and should, install Statspack. Statspack is still there, but unfortunately do not evolve a lot. The most important section, the ‘Top 5 Timed Events’ shows only foreground events, or is supposed to do so. When a user process waits on a background process, this section must count only the foreground wait and not the activity of the background process…