“Oracle *daily* TidBits” (#oratidbit) published at https://www.facebook.com/oraclenotes on weekdays in September 2016. You will also see these tidbits, one tidbit at a time, for each page refresh on the right side of this blog as well… Hope you find these helpful to learn something new or to remind you of its existence and use…
| TidBit |
| #oratidbit VALIDATE DATABASE command in DGMGRL (Data Guard Command Line Interface) shows the database role and if the database is ready for switchover and failoer. |
| #oratidbit Oracle Data Guard far sync instance is a redo transport destination that accepts redo from a primary database and forwards that redo to one or more redo destinations in the configuration. |
| #oratidbit Oracle Virtual Private Database (VPD) enables you to dynamically add a WHERE clause in any SQL statement that a user executes. The WHERE clause filters the data the user is allowed to access, based on the identity of a user. |
| #oratidbit An Oracle Data Guard broker configuration can contain up to 253 members, including one primary database and a combination of standby databases and far sync instances that receive redo directly from the primary database. |
| #oratidbit If a standby database is an Oracle RAC database, only one instance of the Oracle RAC database can have log apply services running at any time. This instance is called the apply instance. If the apply instance fails, the broker automatically moves log apply services to a different instance; this is called apply instance failover. |
| #oratidbit OPTIMAL_LOGFILE_SIZE column in V$INSTANCE_RECOVERY is populated when FAST_START_MTTR_TARGET init parameter is set. Your online redo log file size should be at least OPTIMAL_LOGFILE_SIZE. |
| #oratidbit Oracle ASM natively stripes its content across the ASM members (storage devices). ASM uses two types of striping: coarse-grained striping allocates capacity across ASM disk group member’s round-robin; fine-grained striping, (used by default only for the control files) divides the ASM members into groups of eight, allocates an AU on each, and stripes the newly created data at 128 KB across the eight members, until the AU on each of the members is full. |
| #oratidbit User-created tablespaces are encrypted by default on Oracle Database Cloud #DBaaS. Tablespaces created during database deployment are not encrypted. |
| #oratidbit To create a RAC database on Oracle Database Cloud, you must choose “Extreme Performance” for “Software edition” and Choose Yes for “Setup RAC”. |
| #oratidbit Use raccli utility on Oracle Database Cloud #DBaaS to backup, recover, change backup and security configuration, and patch RAC instances. |
| #oratidbit Use dbaascli utility on Oracle Database Cloud #DBaaS to perform administrative operations such as change password of SYS user, check status and switchover/failover in Dataguard configuration, patch database deployment, database recovery, etc. |
| #oratidbit In Oracle #DB12c 12.2 Container Database, you can have up to 4096 pluggable databases. In 12.1, the limit was 255. |
| #oratidbit In Oracle #DB12c 12.2 container database, undo tablespace can be local to the PDB (new in 12.2) or can use CDB Undo known as shared undo (similar to 12.1). |
| #oratidbit In Oracle #DB12c 12.2 container database, you can flashback a single PDB. In 12.1 you had to flashback the entire CDB. |
| #oratidbit In Oracle #DB12c 12.2, you can failover at PDB-Level using Dataguard Broker. In 12.1 failover is at CDB level. |
| #oratidbit In Oracle #DB12c 12.2, initialization parameter SGA_MIN_SIZE at PDB level guarantees minimum SGA allocation to the PDB. |
| #oratidbit In Oracle #DB12c 12.2, Grid Infrastructure Management Repository can be on separate diskgroup. In 12.1 GIMR is installed on the Voting Disk diskgroup. |