New answers tagged concurrency
The write is done in-memory first and flushed to disk (asynchronously) later. Any readers accessing a document will get the in-memory copy straight away, not waiting for the flush to disk to happen (otherwise the database would be disk bound in terms of performance). The reference about locks applies to the in-memory portion, and guarantees the atomicity ...
The graph is showing the number of sessions in wait. The colors represent a broad category of wait class, which assists in quickly identifying the primary type of wait faced by sessions in the database. The maximum CPU line simply gives you a marker to determine if the amount of CPU wait is reaching extremely critical levels.
You can create several test types with sysbench, but if you look at the typical OLTP tests for SELECTS and INSERTS you will see that the queries executed are similar in pattern, but with random values for each query (not identical every time). If they were identical (something that you could test if you wanted), structures like the query cache and buffer ...
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