Presentation Title: Contemporary Latch Internals
Latches in Oracle Database were radically changed during the last 10 years to achieve higher levels of concurrency and performance. Using oradebug and DTrace, this presentation explores how the latch works. Contemporary latch does not use exponential backoff, most of them spin 10 times more then expected, and they may wait for an infinite time in a queue.
This presentation will show how Oracle instruments the latch operations, discuss parameters and statistics related to latch performance diagnostics, and fine grain tuning. It will also explore the long-standing question: when and how to tune the "_spin_count" and "_latch_classes". DTrace provides additional capabilities to measure effectiveness and statistical properties of latch in production.
Presenter Bio: Andrey Nikolaev was first met with Oracle 5 in 1988. Since that time his professional interests have evolved from high performance particle physics computing, through application development, to database performance consulting, but always stay centered on performance. Working in RDTEX, Russian First Line Support company, he devotes his time to tuning and diagnosing the largest Oracle databases in Russia. As an Oracle University trainer, Andrey taught the full spectrum of Oracle database administration courses.
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