Oracle Transaction - What Is a Data Lock

What Is a Data Lock

Q

What Is a Data Lock? - Oracle DBA FAQ - Understanding SQL Transaction Management

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A

A data lock is logical flag the Oracle server is placed on data objects to give an exclusive right to a transaction. Statements in other transactions needs to respect data locks based on certain rules. Rules on data locks are:

SELECT query statements do not create any data locks.
INSERT, UPDATE, and DELETE statements create data locks on the affected rows.
Data locks are released when the owner transaction ends.

2007-04-17, 4402👍, 0💬

What Are the General Rules on Data Consistency
What Are the General Rules on Data Consistency? - Oracle DBA FAQ - Understanding SQL Transaction Management All SQL statements always work with a snapshot of the database to provide data consistency. For READ WRITE transactions, the snapshot is taken when each statement starts. For READ ONLY transac... 2007-04-17, 4616👍, 0💬

What Is a Data Lock
What Is a Data Lock? - Oracle DBA FAQ - Understanding SQL Transaction Management A data lock is logical flag the Oracle server is placed on data objects to give an exclusive right to a transaction. Statements in other transactions needs to respect data locks based on certain rules. Rules on data loc... 2007-04-17, 4403👍, 0💬

How To Experiment a Data Lock
How To Experiment a Data Lock? - Oracle DBA FAQ - Understanding SQL Transaction Management If you want to have some experience with data locks, you can create two windows runing two SQL*Plus sessions. In session 1, you can run a UPDATE statements to create a data lock. Before committing session 2, s... 2007-04-17, 4383👍, 0💬

How Data Locks Are Respected
How Data Locks Are Respected? - Oracle DBA FAQ - Understanding SQL Transaction Management Here are the rules on how data locks are respected: All statements ignore data locks owned its own transaction. SELECT query statements ignores data locks owned by any transactions. INSERT, UPDATE, and DELETE s... 2007-04-17, 4378👍, 0💬

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