Table x$ksppi contains all documented and undocumented (aka hidden, which status with _ [underscore]); joining with x$ksppcv table on column indx will provide parameter name, value and description.
OERR stands for Oracle Error, which is a utility ships with Oracle distribution for Linux and UNIX that helps retrieve messages from message (.msg) files based on the supplied error code. This utility is not available for Windows, but there are variants freely available on the Internet.
Jul 022009
PLAN_TABLE is the default sample output table into which the EXPLAIN PLAN statement inserts rows describing execution plans. This post summarizes the metadata information of this table for Oracle8/8i, 9i, 10g, and 11g; read post, to know the methods for obtaining the formatted explain plan output from plan_table. Column Datatype Description Notes STATEMENT_ID VARCHAR2(30) Value [...]
Statspack is a set of SQL, PL/SQL and SQL*Plus scripts which allow the collection, automation, storage and viewing of performance data. A user, PERFSTAT, is automatically created by the installation; owns all objects needed by this package. This user is granted limited query-only privileges on the V$views required for performance tuning. A Statspack report is generated from two snapshots, which is nothing but a collection of contents from various dynamic performance tables.
The DBMS_PROFILER package provides an interface to profile existing PL/SQL applications and identify performance bottlenecks. You can then collect and persistently store the PL/SQL profiler data.
You can have multiple instances on the same machine, each with their own data files, either sharing the ORACLE_HOME or each with different ORACLE_HOME. ORACLE_HOME and ORACLE_SID are the key environment variables used by Oracle to identify an instance. In addition $ORACLE_HOME/bin must be in your PATH environment variable. To check the value of these [...]
To execute any SQL statement Oracle has to derive an ‘execution plan’ . The execution plan of a query is a description of how Oracle will implement the retrieval of data to satisfy a given SQL statement. It is nothing but a tree which contains the order of steps and relationship between them.
You can automatically get a report on the execution path used by the SQL optimizer and the statement execution statistics. The report is generated after successful SQL DML (that is, SELECT, DELETE, UPDATE and INSERT) statements. It is useful for monitoring and tuning the performance of these statements. To use this feature, you must create a PLAN_TABLE table in your schema and then have the PLUSTRACE role granted to you. DBA privileges are required to grant the PLUSTRACE role.
Methods required to obtain a formatted explain plan differ depending on which version of Oracle you are using. The initial steps to create a plan table and make the optimizer populate the plan table with the execution plan are common to all versions of Oracle.
One of my all time favorite analytical functions are the LAG (look back) and LEAD (look ahead) functions, which were first introduced in Oracle 8i. It provides access to more than one row of a table at the same time without a self join. Given a series of rows returned from a query and a [...]