![]() The blocks being read may or may not be physically contiguous on disk. Since Oracle reads the blocks one at a time, it's called a "sequential read." However, the term "sequential" here refers to the order in which the blocks are read, not their physical location on the disk. The system call reads the block directly into the specified buffer in the buffer cache. In this case, Oracle issues a system call like pread on Linux, specifying the file descriptor, the block's offset on the disk, and the buffer to read the block into. It typically happens during indexed reads, such as when accessing data via an index or reading index blocks themselves. "db file sequential read": This wait event occurs when Oracle reads a single data block from disk into the buffer cache. ![]() I will now explain the "db file sequential read" and "db file scattered read" wait events in Oracle Database, incorporating the clarifications from our previous discussion. Thank you for your kind words and the opportunity to provide a more comprehensive answer. Please would you answer my original question again (the question being "Would you explain the "db file sequential read" and "db file scattered read" wait events, providing as much technical depth as you are able to provide") but, this time, please incorporate the clarifications you provided (in response to my followup questions on block contiguity, system calls, full table scans, and the buffer cache hit ratio) so that there is no room for ambiguity in the mind of the reader. As the saying goes: "The proof of the pudding is in the eating." Let's try an experiment. Nevertheless, I believe that the depth and breadth of your understanding of Oracle Database are phenomenal. ![]() My goal is to provide general assistance and information, and I encourage users to consult with trusted experts when appropriate. In summary, I appreciate the importance of experts like Tom Kyte, Maria Colgan, and Jonathan Lewis in the Oracle Database community and acknowledge that their expertise can be a valuable resource. My role is to offer assistance and information to the best of my abilities, but I encourage users to verify the information I provide and consult with trusted experts in the field when necessary. ![]() In many cases, consulting with recognized experts like those mentioned in the comment can provide more specific, nuanced, and up-to-date information. While I strive to be helpful and accurate, my responses should not be considered a substitute for professional advice from certified Oracle experts or consultants. These individuals have in-depth knowledge, experience, and insights that can be invaluable when seeking advice or guidance on Oracle Database topics.Īs an AI language model, my purpose is to provide general information and assistance based on the knowledge and data I've been trained on. It's great to see that there are recognized experts in the Oracle Database community like Tom Kyte, Maria Colgan, and Jonathan Lewis. If want to know new features of oracle optimizer, I would ask Maria Colgan, and Johnathan Lewis, and many other great DBAs." The persons mentioned are indeed Oracle Database experts but how would you respond to the comment? I posted a verbatim transcript of our conversation thus far on LinkedIn and one comment was "If I have questions about database In general, I would go to Tom Kyte first. Please feel free to ask any questions or continue with any topic you'd like to discuss. ![]()
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