Different settings work best for servers with light, predictable loads, versus servers that are running near full capacity all the time, or that experience spikes of high activity.
Because the InnoDB storage engine performs
many of its optimizations automatically, many performance-tuning
tasks involve monitoring to ensure that the database is
performing well, and changing configuration options when
performance drops. See
Section 13.7.7.17, “Integration with MySQL PERFORMANCE_SCHEMA” for information
about detailed InnoDB performance monitoring.
For information about the most important and most recent
InnoDB performance features, see
Section 13.7.7, “Performance and Scalability Enhancements”. Even if you have used
InnoDB tables in prior versions, these
features might be new to you, because they are from the
“InnoDB Plugin”. The Plugin co-existed alongside
the built-in InnoDB in MySQL 5.1, and becomes
the default storage engine in MySQL 5.5 and higher.
The main configuration steps you can perform include:
Enabling
InnoDBto use high-performance memory allocators on systems that include them. See Section 13.7.7.3, “Using Operating System Memory Allocators”.Controlling the types of DML operations for which
InnoDBbuffers the changed data, to avoid frequent small disk writes. See Section 13.7.7.4, “Controlling InnoDB Change Buffering”. Because the default is to buffer all types of DML operations, only change this setting if you need to reduce the amount of buffering.Turning the adaptive hash indexing feature on and off. See Section 13.7.7.5, “Controlling Adaptive Hash Indexing”. You might change this setting during periods of unusual activity, then restore it to its original setting.
Setting a limit on the number of concurrent threads that
InnoDBprocesses, if context switching is a bottleneck. See Section 13.7.7.6, “Changes Regarding Thread Concurrency”.Controlling the amount of prefetching that
InnoDBdoes with its read-ahead operations. When the system has unused I/O capacity, more read-ahead can improve the performance of queries. Too much read-ahead can cause periodic drops in performance on a heavily loaded system. See Section 13.7.7.7, “Changes in the Read-Ahead Algorithm”.Increasing the number of background threads for read or write operations, if you have a high-end I/O subsystem that is not fully utilized by the default values. See Section 13.7.7.8, “Multiple Background I/O Threads”.
Controlling how much I/O
InnoDBperforms in the background. See Section 13.7.7.11, “Controlling the Master Thread I/O Rate”. The amount of background I/O is higher than in MySQL 5.1, so you might scale back this setting if you observe periodic drops in performance.Controlling the algorithm that determines when
InnoDBperforms certain types of background writes. See Section 13.7.7.12, “Controlling the Flushing Rate of Dirty Pages”. The algorithm works for some types of workloads but not others, so might turn off this setting if you observe periodic drops in performance.Taking advantage of multicore processors and their cache memory configuration, to minimize delays in context switching. See Section 13.7.7.14, “Control of Spin Lock Polling”.
Preventing one-time operations such as table scans from interfering with the frequently accessed data stored in the
InnoDBbuffer cache. See Section 13.7.7.15, “Making Buffer Cache Scan Resistant”.Adjusting your log files to a size that makes sense for reliability and crash recovery. See Section 13.7.7.16, “Improvements to Crash Recovery Performance”. Historically, people have kept their
InnoDBlog files small to avoid long startup times after a crash. Internal improvements inInnoDBmake startup much faster, so the log file size is not such a performance factor anymore. If your log files are artificially small, increasing the size can help performance by reducing the I/O that occurs as redo log records are recycled.Configuring the size and number of instances for the
InnoDBbuffer pool, especially important for systems with multi-gigabyte buffer pools. See Section 13.7.7.18, “Improvements to Performance from Multiple Buffer Pools”.Increasing the maximum number of concurrent transactions, which dramatically improves scalability for the busiest databases. See Section 13.7.7.19, “Better Scalability with Multiple Rollback Segments”. Although this feature does not require any action during day-to-day operation, you must perform a slow shutdown during or after upgrading the database to MySQL 5.5 to enable the higher limit.
Moving purge operations (a type of garbage collection) into a background thread. See Section 13.7.7.20, “Better Scalability with Improved Purge Scheduling”. To effectively measure the results of this setting, tune the other I/O-related and thread-related configuration settings first.
Reducing the amount of switching that
InnoDBdoes between concurrent threads, so that SQL operations on a busy server do not queue up and form a “traffic jam”. Set a value for theinnodb_thread_concurrencyoption, up to approximately 32 for a high-powered modern system. Increase the value for theinnodb_concurrency_ticketsoption, typically to 5000 or so, This combination of options sets a cap on the number of threads thatInnoDBprocesses at any one time, and allows each thread to do substantial work before being swapped out, so that the number of waiting threads stays low and operations can complete without excessive context switching.