mysql temp table performance

+ ------------ + ------------------- + --------------------- + Region + -------------------- + | select if ('locate '(?, '...' COMPRESSED _ size') DESC | 2 | 4 | 2 | 2 | 50 | select if ('locate '(?, '... MPRESSED_SIZE' =? ),? ,... | 2 | 4 | 2 | 2 | 50 | select if ('isnull' ('inform... '= 'performance _ scheme '.... | 2 | 4 | 2 | 2 | 50 | select if ('isnull' ('inform... by_thread_by_event_name '.... | 2 | 4 | 2 | 2 | 50 | show full fields from 'statem

statement. This is recorded as many events that are updated by a number of records. NaturalThe amount of Binary log logs will be very large. Especially when executing statements such as Alter TABLE, the amount of log generated is staggering. Because MySQL handles DDL change statements such as ALTER table by rebuilding all the data in the entire

First, performance detection and bottleneck analysis 1 common commands for performance detection Show status Display status information, reference: Mysql Show status Command detailed Show Processlist View current SQL execution, including execution status, whether to lock the table, etc., reference:

In-depth analysis of MySQL database engine introduction, differences, creation and performance testing bitsCN.com Database Engine introduction The MySQL database engine depends on how MySQL is compiled during installation. To add a new engine, you must recompile MYSQL. By de

MySQL latency Association performance optimization method and mysql latency performance optimization Background] An error occurred while alerting the load of a business database. The cpu usr reached 30-40, which remained high. Use tools to view the SQL statements being executed by the database. The most advanced ones a

for each unique open table The file descriptor. The default value is 64, and I'll change it to 512. (8) Thread_cache_size:The number of threads stored in that can be reused. If there is, a new thread is obtained from the cache, and when disconnected, if there is room, the customer's line Placed in the cache. If there are a lot of new threads, in order to improve performance you can have this variable va

Today, database operations are increasingly becoming a performance bottleneck for the entire application, which is especially noticeable for web applications. It's not just about the performance of the database that DBAs need to worry about, it's something that our programmers need to focus on. When we design the database table structure, we need to pay attention

Mysql performance optimization configuration parameters and mysql performance optimization parameters To modify the values of the following parameter configuration items, refer1. connection settingsShow variables like '% max_connection % ';Show status like '% Max_used_connections % ';Max_used_connections/max_connection

Tags: set multi-line optimization name function official same scheme performanceIn database design, if the query is written badly, even if the library table structure design is reasonable, the index can not achieve high performance.1. Optimize data accessThe most basic reason for poor query performance is that there is too much data to access. For inefficient que

. However, we should also be clear that if the remote table structure is changed, the local table definition information will not change accordingly. If the local Federated table definition information is not updated when the remote table structure is updated, the Query operation may fail and the correct results may no

. In other words, the subquery is executed first, and then the main query is executed based on the results of the subquery.Keywords: the keywords used for subqueries mainly include in, not in, EXIST, not EXIST, =, Note: MySQL does not support SQL subqueries from 4.1 onwards. It is generally said that subqueries are less efficient than connection queries (because subqueries require at least two queries, or at least two SELECT statements.) Sub-query nes

cachingObjective: to cache the query results of select in memory for the next direct fetch;Query_cache_type = 1query_cache_size = 64mquery_cache_limit = 1MFor the cache expiration policy, the mechanism used by MySQL is: When a table has an update operation, all query caches involving the table will be invalidated;This scenario, for dense select operations and ra

21 best practices for MySQL Performance Optimization bitsCN.com Today, database operations are increasingly becoming the performance bottleneck of the entire application, especially for Web applications. Concerning the database performance, this is not just something that DBAs need to worry about, but it is something t

connection information, port number, socket storage location [Mysqld]port=3306Socket=/usr/local/mysql/data/Mysql.sockbasedir=/usr/local/Mysqldatadir=/usr/local/mysql/Datatemdir=/usr/local/mysql/data## Mysql Basic information, port number, socket, installation directory, data storage directory,

20 + sets of best MySQL Performance Optimization experience bitsCN.com 20 + sets of best MySQL Performance Optimization experience Today, database operations are increasingly becoming the performance bottleneck of the entire application, especially for Web applications. Co

Today, database operations are increasingly becoming a performance bottleneck for the entire application, which is especially noticeable for web applications. It's not just about the performance of the database that DBAs need to worry about, it's something that our programmers need to focus on. When we design the database table structure, we need to pay attention

amount of data that the server needs to scan2. Indexing can help the server avoid sorting and staging tables3. Indexes can turn random I/O into sequential I/OIn general, the index is valid only if the index helps the storage engine to quickly find the benefits of records that outweigh the additional work that it brings. For very small tables, a simple full table scan is more efficient in most cases. Indexes are very effective for medium to large tabl

Today, database operations are increasingly becoming a performance bottleneck for the entire application, which is especially noticeable for web applications. It's not just about the performance of the database that DBAs need to worry about, it's something that our programmers need to focus on. When we design the database table structure, we need to pay attention

used for sorting, we can see the obvious direct path write temp and direct path read temp in the trac file formatted in 10046, also because it is your own testing machine (T430 ), SQL Execution of analysis functions consumes your own pc resources. For these SQL requests, the advantage of the analysis function is to reduce the number of table scans, but there is

temporary table space is created. In other words, no storage space is allocated for temporary files. Only temporary data occurs when temporary files are needed, and the system allocates a place on the hard disk to hold temporary files. At this point, there may be a problem, that is, when the temporary file system is needed to allocate space, the system partition does not have enough storage space. At this point there will be some unpredictable conseq