Xaprb (Baron) recently blogged about how InnoDB performs a checkpoint , I thought it might be useful to explain another important mechanism that affects both response time and throughput – The transaction log.
In my recent benchmarks, such as this one about the Virident TachIon card, I used different values for innodb_buffer_pool_size, like 13GB, 52GB, and 144GB, for testing the tpcc-mysql database with size 100G. This was needed in order to test different memory/dataset size ratios. But why is it important, and how does it affect howÂ InnoDB works […]
In my post MySQL 5.5.8 and Percona Server: being adaptive I mentioned that I used innodb-log-block-size=4096 in Percona Server to get better throughput, but later Dimitri in his article MySQL Performance: Analyzing Percona’s TPCC-like Workload on MySQL 5.5 sounded doubt that it really makes sense. Here us quote from his article: “Question: what is a […]
How long it may take MySQL with Innodb tables to shut down ? It can be quite a while. In default configuration innodb_fast_shutdown=ON the main job Innodb has to do to complete shutdown is flushing dirty buffers. The number of dirty buffers in the buffer pool varies depending on innodb_max_dirty_pages_pct as well as workload and […]
InnoDB has an oft-unused parameter innodb_concurrency_tickets that seems widely misunderstood. From the docs: “The number of threads that can enter InnoDB concurrently is determined by the innodb_thread_concurrency variable. A thread is placed in a queue when it tries to enter InnoDB if the number of threads has already reached the concurrency limit. When a thread […]
I can think of at least two major reasons why systems delay flushing changes to durable storage: 1. So they can do the work when it’s more convenient. 2. So they can do less work in total. Let’s look at how the second property can be true.
I recently had the chance to witness the effects of innodb_adaptive_flushing on the performance of InnoDB Plugin 1.0.5 in the wild, which Yasufumi wrote about previously here and here. The server in question was Solaris 10 with 8 disk RAID10 and 2 32GB SSDs used for ZIL and L2ARC, 72G RAM and 40G buffer pool. […]
Recently I looked at table_cache sizing which showed larger table cache does not always provides the best performance. So I decided to look at yet another similar variable – innodb_open_files which defines how many files Innodb will keep open while working in innodb_file_per_table mode. Unlike MyISAM Innodb does not have to keep open file descriptor […]
Sometimes a MySQL server running InnoDB takes a long time to shut down. The usual culprit is flushing dirty pages from the buffer pool. These are pages that have been modified in memory, but not on disk. If you kill the server before it finishes this process, it will just go through the recovery phase […]
As larger and larger amount of memory become common (512GB is something you can fit into relatively commodity server this day) many customers select to build their application so all or most of their database (frequently Innodb) fits into memory. If all tables fit in Innodb buffer pool the performance for reads will be quite […]