enq: TM - contention Wait Event , Cause, Related SQL queries, Possible Resolution

The "enq: TM - contention" wait event in Oracle indicates contention for a table-level lock. This contention occurs when multiple sessions are attempting to acquire conflicting table-level locks concurrently, leading to performance issues as sessions have to wait for the locks to be released before they can proceed with their operations. 

 While there are similarities in the resolution strategies for "enq: TX - index contention" and "enq: TM - contention," they do involve different types of contention (index-level vs. table-level). To clarify, here are specific resolution strategies for "enq: TM - contention" related to table-level lock contention: 

enq: TX - index contention Wait Event , Cause, Related SQL queries, Possible Resolution

The "enq: TX - index contention" wait event in Oracle occurs when multiple database sessions are contending for locks on the same index block. This contention can lead to performance issues as sessions have to wait for the locks to be released before they can proceed with their operations.

 Explanation: 

 In Oracle, locks are used to control access to data structures, including index blocks, to maintain data consistency and integrity. 

enq: TX - row lock contention Wait Event , Cause, Related SQL queries, Possible Resolution

The "enq: TX - row lock contention" wait event in Oracle occurs when multiple database sessions are contending for locks on the same row in a table. This contention can lead to performance issues, as sessions have to wait for the locks to be released before they can proceed with their operations.

 Explanation: In Oracle, locks are used to control access to data to maintain data consistency and integrity. 

Latch Free Wait Event , Cause, Related SQL queries, Possible Resolution

wait event in Oracle occurs when a session is trying to acquire a latch but finds it unavailable, resulting in a wait condition. Latches are low-level synchronization mechanisms used by Oracle to protect shared data structures in the SGA (System Global Area) from concurrent access. 

 Explanation: Latches are used to coordinate access to data structures like buffers in the buffer cache, library cache, or other shared memory structures. 

The "Latch Free" wait event happens when a session is waiting for a latch to become available. 

The wait event can occur for various reasons, including contention for a particular latch, inefficient latch acquisition patterns, or excessive latch acquisition requests. 

Log file sequential read Wait Event , Cause, Related SQL queries, Possible Resolution

The "log file sequential read" wait event occurs when a session is waiting for a single redo log file block to be read from disk into the buffer cache in a sequential manner. This wait event is common during log file access operations, such as reading redo log records during recovery or archive log processing. 

 Explanation: During database operations, especially during recovery processes, Oracle may need to read specific redo log records stored in redo log files on disk. 

The "log file sequential read" wait event indicates that a session is waiting for an I/O operation to complete, bringing the requested redo log block into the buffer cache.

Fix runInstaller [INS-32042] The Installer has detected that the user (oracle) is not member of the central inventory group: wheel

Problem Description

Oracle installation or runinstaller failed with below error message. 

[INS-32042] The Installer has detected that the user (oracle) is not member of the central inventory group: wheel

log file parallel write Wait Event , Cause, Related SQL queries, Possible Resolution

The "log file parallel write" wait event occurs when Oracle is writing redo log information to multiple redo log files in parallel. This wait event is related to the process of committing transactions and ensuring that redo log records are safely stored on disk. 

 Explanation: 

 During a transaction commit, the changes (redo log records) made in the transaction need to be written to the redo log files on disk to ensure data durability. 

log file sync Wait Event , Cause, Related SQL queries, Possible Resolution

The "log file sync" wait event occurs when a session is waiting for a commit's redo records to be written from the redo log buffer to the redo log file on disk. This wait event is crucial for ensuring data durability and is typically associated with transaction commits. 

 Explanation: 

 When a user or application commits a transaction, the changes (redo records) are first written to the redo log buffer in memory. 

db file scattered read - Wait Event , Cause, Related SQL queries, Possible Resolution

The "db file scattered read" wait event occurs when a session is waiting for multiple data blocks to be read from disk into the buffer cache in a scattered manner. This wait event is common when a query or operation requires access to multiple non-adjacent data blocks that are not currently in memory. Explanation: This wait event indicates that a session is waiting for I/O operations to complete, bringing the requested data blocks into memory. It often occurs during full table scans or index range scans where multiple non-contiguous blocks are read.

db file sequential read - Wait Event , Cause, Related SQL queries, Possible Resolution

The "db file sequential read" wait event occurs when a session is waiting for a single data block to be read from disk into the buffer cache in a sequential manner. This wait event is common when a query or operation requires access to a specific data block that is not currently in memory. Explanation: This wait event indicates that a session is waiting for the I/O operation to complete, bringing the requested data block into memory. It usually occurs during SELECT operations or when an index is being accessed. It's a normal part of database operations, especially in OLTP systems where individual data blocks are frequently accessed. 

How to Get Bind Variable Value in Oracle Database

To retrieve the value of a bind variable in Oracle, you can use the V$SQL_BIND_CAPTURE view or the DBMS_APPLICATION_INFO package, depending on your use case. Here's how you can do it: Using V$SQL_BIND_CAPTURE View: The V$SQL_BIND_CAPTURE view provides information about captured bind values for SQL statements in the library cache. You can query this view to retrieve the values of bind variables for specific SQL statements. 

How to Get or Display Explain Plan of SQL Baseline - DBMS_XPLAN.display_sql_plan_baseline

you can use the DBMS_XPLAN. DISPLAY_SQL_PLAN_BASELINE procedure to display the execution plan associated with a specific SQL Baseline. This procedure is part of the DBMS_XPLAN package and is designed to show the execution plan for a SQL statement using its SQL ID or SQL handle, including those stored in SQL Plan Baselines. Here's an example of how to use DBMS_XPLAN.DISPLAY_SQL_PLAN_BASELINE:

Fix Error: ORA-13541: system moving window baseline size (691200) greater than retention (259200)

Problem Description:

When I trying to change the AWR snapshot setting I am getting below error. 

Error: ORA-13541: system moving window baseline size (691200) greater than retention (259200)

SQL> get afiedt.buf
  1  DECLARE
  2    retention_num NUMBER;
  3    interval_num NUMBER;
  4  BEGIN
  5    -- Set the desired snapshot retention period (in days)
  6    retention_num := 3*24*60;
  7    -- Set the desired snapshot interval (in minutes)

DBMS_XPLAN - Script To get The Explain Plan from cursor

To retrieve the execution plan (explain plan) for a specific cursor in an Oracle database, you can use the following SQL*Plus script. This script uses the DBMS_XPLAN package to display the execution plan for a given SQL statement: An execution plan (explain plan) provides insights into how Oracle's query optimizer intends to execute a given SQL statement. It shows the sequence of operations and access paths used to retrieve data from the database.

How to Get Oracle Redo Log Files, Members, Size, Name and Status - Query

To retrieve redo log information from an Oracle database, you can use the following SQL*Plus script. This script queries the V$LOG view to provide details about the redo log files in the database. Redo logs are a critical component of Oracle databases. They record all changes made to the database, allowing for recovery and transaction consistency. The redo log files are divided into groups, and each group contains one or more members (physical files). The V$LOG view provides information about redo log groups in the database, including their sequence numbers, sizes, members, statuses, and other details. Please note that querying the V$LOG view requires appropriate privileges. Test the script in a controlled environment before running it in a production database.

How to Find / Retrieve / Get ACL details in Oracle Database

To retrieve the ACL (Access Control List) details in an Oracle database, you can use the following SQL script. This script queries the DBA_NETWORK_ACLS and DBA_NETWORK_ACL_PRIVILEGES views to get information about the ACLs and their privileges: An Access Control List (ACL) in Oracle is a list of network privileges for a particular host and a specific principal (user or role). 

ACLs control the network access rights of database users and roles. Each ACL is associated with a specific host, and you can grant or deny network privileges to specific principals for that host. ACLs are essential for managing network access to and from the Oracle database, especially when the database interacts with external services or applications over the network.

How to Find out Oracle Database Uptime in Hours or Days - Script

To find out the database uptime in Oracle, you can use the following SQL script. This script calculates the database uptime by subtracting the startup time from the current time Database uptime refers to the duration of time that a database has been running since its startup. 

Monitoring database uptime is important for ensuring the availability and reliability of the database. It helps track how long the database has been operational and can be useful for performance analysis, maintenance planning, and system monitoring. The v$instance view in Oracle provides information about the current instance of the database, including the startup time.

How to Enable or Disable All Triggers in a Oracle Schema - Script

To disable all triggers in an Oracle schema, you can use the following SQL script. This script generates the necessary SQL statements to disable all triggers and then executes them. Disabling triggers can be useful in scenarios where you need to temporarily suspend their execution, such as during data maintenance, bulk loading, or troubleshooting activities. Disabling triggers can prevent them from firing and affecting the normal operation of the database.

Script to Find out Row Count of All the Tables in a schema

To retrieve the row count of all the tables in a schema, you can use the following SQL script. This script queries the DBA_TABLES view to get the row count for each table in the specified schema

col table_name for a40 

SELECT
  table_name,
  num_rows
FROM
  all_tables
WHERE
  owner = 'YOUR_SCHEMA_NAME';

Script to Find and Cleanup Orphaned Datapump Jobs

Orphaned Data Pump jobs are jobs that have been left behind due to various reasons, such as an interruption or error during the execution of the job. These orphaned jobs are not actively running but are still present in the database. To clean up these orphaned Data Pump jobs, you can use the following script