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You're reading from  Developing Robust Date and Time Oriented Applications in Oracle Cloud

Product typeBook
Published inMay 2023
PublisherPackt
ISBN-139781804611869
Edition1st Edition
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Michal Kvet
Michal Kvet
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Michal Kvet

Michal Kvet is a researcher, educator, and database expert at the University of Žilina in Slovakia. His primary focus areas are databases, analytics, performance, and cloud computing. He works closely with Oracle and Oracle Academy. He is the co-author of multiple textbooks (a SQL and PL/SQL cookbook, a book on APEX application development, a book on temporal databases, and a MySQL cookbook), coordinates multiple Erasmus+ projects and co-organizes several research conferences and database workshops. Besides this, he supervises engineering projects and bachelor's, master's, and doctoral theses. Over the years, his research has been associated with date and time management and temporal databases. He has Oracle's SQL, PL/SQL, Cloud, Analytics, and Administration certifications. His core knowledge of temporality is provided to you in this book.
Read more about Michal Kvet

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Transaction log structure and log types

Transaction logs describe the operations that are executed inside the transaction. Each log consists of the transaction position reference, the System Change Number (SCN), the individually performed operation, and the change vector. From this perspective, transaction logs can be divided into two groups – UNDO and REDO structures. An UNDO log stream stores the original data to allow the system to refuse transactions and revert individual operations to their original state. It is physically stored in the UNDO tablespace in the database. On the other hand, the REDO log stream is stored primarily in memory and then copied to the Online REDO log files, which are crucial to the Oracle database. This allows us to replay the approved transaction to get the state of the database just before the database instance or media failure. The Log Writer (LGWR) background process operates transaction log management.

Both streams are periodically overwritten...

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Developing Robust Date and Time Oriented Applications in Oracle Cloud
Published in: May 2023Publisher: PacktISBN-13: 9781804611869

Author (1)

author image
Michal Kvet

Michal Kvet is a researcher, educator, and database expert at the University of Žilina in Slovakia. His primary focus areas are databases, analytics, performance, and cloud computing. He works closely with Oracle and Oracle Academy. He is the co-author of multiple textbooks (a SQL and PL/SQL cookbook, a book on APEX application development, a book on temporal databases, and a MySQL cookbook), coordinates multiple Erasmus+ projects and co-organizes several research conferences and database workshops. Besides this, he supervises engineering projects and bachelor's, master's, and doctoral theses. Over the years, his research has been associated with date and time management and temporal databases. He has Oracle's SQL, PL/SQL, Cloud, Analytics, and Administration certifications. His core knowledge of temporality is provided to you in this book.
Read more about Michal Kvet