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HOSxP => MySQL => ข้อความที่เริ่มโดย: มนตรี บอยรักยุ้ยคนเดียว ที่ พฤษภาคม 07, 2011, 12:11:18 PM
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รอมานานหลังจามีปัญหาต้องหยุดพัฒนาไป ออกวันนี้
http://mirror.services.wisc.edu/mysql/Downloads/MySQL-5.6/
test speed MySQL-5.6
Changes in 5.6
In 5.6 we have the same parameters as 5.5 except that innodb-purge-threads can now be between 0 and 32. This introduces true multi threaded purging. If the value is greater than 1 then InnoDB will create that many purge worker threads and a dedicated purge coordinator thread. The responsibility of the purge coordinator thread is to parse the UNDO log records and parcel out the work to the worker threads. The coordinator thread also purges records, instead of just sitting around and waiting for the worker threads to complete. The coordinator thread will divide the innodb-purge-batch-size by innodb-purge-threads and hand that out as the unit of work for each worker thread.
Multi-Threaded Purge
InnoDB now has multiple purge threads, making purge operations across multiple tables more efficient. Originally, purge operations were handled by the InnoDB master thread, leading to contention with other InnoDB operations; in MySQL 5.5, purge was moved into a single separate thread, and in MySQL 5.6 you can set innodb_purge_threads to a value greater than 1. Read more about multiple purge threads.
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สำหรับ MySQL-5.5
Changes in 5.5
In 5.5 there is an option innodb-purge-threads=[0,1] to create a dedicated thread that purges asynchronously if there are UNDO logs that need to be removed. We also introduced another option innodb-purge-batch-size that can be used to fine tune purge operations. The batch size determines how many UNDO log pages purge will parse and process in one pass. The default setting is 20, this is the same as the hard coded value that is in previous InnoDB releases. An interesting side effect of this value is that it also determines when purge will free the UNDO log pages after processing them. It is always after 128 passes, this magic value of 128 is the same as the number of UNDO logs in the system tablespace, now that 5.5 has 128 rollback segments. By increasing the innodb-purge-batch-size the freeing of the UNDO log pages behaviour changes, it will increase the number of UNDO log pages that it removes in a batch when the limit of 128 is reached. This change was seen as necessary so that we could reduce the cost of removing the UNDO log pages for the extra 127 rollback segments that were introduced in 5.5. Prior to this change iterating over the 128 rollback segments to find the segment to truncate had become expensive.