Oracle Tidbits – February 2015

Oracle *daily* TidBits” (#oratidbit) published at on weekdays in February 2015. 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…

Publish Date TidBit
2-Feb #oratidbit SRVCTL commands and components are case insensitive. Options are case sensitive. Database and database service names are case insensitive and case preserving.
3-Feb #oratidbit “srvctl setenv” command sets values of environment variables in the Oracle Restart configuration for a database, a listener, or the Oracle ASM instance.
4-Feb #oratidbit “crsctl check has” displays the Oracle Restart (srvctl) configuration.
5-Feb #oratidbit “srvctl status home” displays the running status of all of the components that are managed by Oracle Restart in the specified Oracle home.
9-Feb #oratidbit ALTER SYSTEM ARCHIVE LOG CURRENT statement in RAC database will force a log switch on all instances. Oracle Database archives all redo log file groups from all enabled threads, including logs previous to current logs.
10-Feb #oratidbit “crctl eval” command enables (in RAC or Oracle Restart) to simulate a command without making any changes to the system. CRSCTL returns output that informs you what will happen if you run a particular command.
11-Feb #oratidbit The Oracle Interface Configuration Tool (OIFCFG) command-line interface can be used to define and administer network interfaces in RAC environment. “oifcfg iflist” shows the available interfaces to configure. The iflist command queries the operating system to find which network interfaces are present on the node.
12-Feb #oratidbit In RAC environment, use the ocrconfig command to manage Oracle Cluster Registry (OCR). Using ocrconfig you can import, export, add, delete, restore, overwrite, backup, repair, replace, move, upgrade, or downgrade OCR.
13-Feb #oratidbit In RAC environment, olsnodes command provides the list of nodes and other information for all nodes participating in the cluster. The “olsnodes -i” lists all nodes participating in the cluster and includes the Virtual Internet Protocol (VIP) address (or VIP address with the node name) assigned to each node.
16-Feb #oratidbit #Oracle Trace File Analyzer (TFA) is installed automatically with Oracle Grid Infrastructure & It simplifies the diagnostic data collection for Oracle Clusterware, Oracle Grid Infrastructure, and Oracle RAC systems. To install or upgrade with latest version of TFA, use MOS Doc 1513912.1.
17-Feb #oratidbit The most simplistic form of data collection using Trace File Analyzer (TFA) is “tfactl diagcollect”. It will collect and trim log and trace files for the past 4 hours, these logs/traces include: Clusterware/GI, ASM, Database (from all databases) OS, OSWatcher, CHMOS and Procwatcher.  All diagnostic data will be trimmed to this 4 hour window and consolidated for upload to the node in which the diagcollection command was executed on. See MOS Doc 1513912.1
18-Feb #oratidbit Every time an Oracle Clusterware error occurs, run the “Grid_home/bin/” script as root user to collect diagnostic information from Oracle Clusterware into trace files. The TFA diagnostics provide additional information so My Oracle Support can resolve problems.
19-Feb #oratidbit The Automatic Diagnostic Collection feature of Trace File Analyzer (TFA) is disabled by default. To enable do “tfactl set autodiagcollect=ON -c” See MOS Doc 1513912.1
20-Feb #oratidbit Trace File Analyzer (TFA) now includes DB Support tools such as ORAChk, EXAChk, OSWatcher, ProcWatcher, ORATOP, SQLT as well as basic AWR report generation. See MOS Doc 1513912.1
23-Feb #oratidbit Heat Map and Automatic Data Optimization are two new features of the #Oracle Advanced Compression option for Oracle #DB12c. Heat Map automatically tracks data modification and query timestamps, providing details of how data is being used. It collects statistical information about the usage frequency or “heat” of a segment, such as a table or a partition.
24-Feb #oratidbit In #Oracle #DB12c, the HEAT_MAP initialization parameter enables both Heat Map and Automatic Data Optimization.
25-Feb #oratidbit JSON (JavaScript Object Notation) is a lightweight data-interchange format. Oracle #DB12c supports JSON natively with relational database features, including transactions, indexing, declarative querying, and views. To see which columns include JSON data, query the USER_JSON_COLUMNS view.
26-Feb #oratidbit With Adaptive Plans feature of Oracle #DB12c, the execution plan of the query may change after starting the execution. During the parse phase of a query, the optimizer computes an execution plan based on the information gathered from the statistics. Optimizer also computes alternative plans called subplans. During query execution, a statistics collector collects runtime statistics, and if a subplan proves to be better than the originally computed plan, the optimizer will make a course correction and choose that subplan.
27-Feb #oratidbit OPTIMIZER_DYNAMIC_SAMPLING in #DB12c has a new level 11. Level 11 enables the optimizer to automatically decide to use dynamic statistics for any SQL statement, even if all basic table statistics exist.

2 Responses to Oracle Tidbits – February 2015

  1. Excellent knowledge shared this past February

  2. Thank you James.

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