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https://dev.mysql.com/doc/connector-odbc/en/connector-odbc-usagenotes-functionality-performance.html
If you experience problems with the performance of Connector/ODBC, or notice a large amount of disk activity for simple queries, there are a number of aspects to check: Ensure that ODBC Tracing is not enabled. The Connector/ODBC driver has been ...
https://dev.mysql.com/doc/connector-python/en/connector-python-tutorial-cursorbuffered.html
The following example script gives a long-overdue 15% raise effective tomorrow to all employees who joined in the year 2000 and are still with the company. (A buffered cursor fetches and buffers the rows of a result set after executing a query; see ...
https://dev.mysql.com/doc/internals/en/calling-sequence.html
For simple non-grouping queries only Section 18.1.3, “send_row()” is called once for each result row. For grouping queries add() is called once for each source row. The init callback is always called first at the beginning of a query, followed ...
https://dev.mysql.com/doc/internals/en/frm-file-format.html
Regardless of the storage engine you choose, every MySQL table you create is represented on disk by a .frm file that describes the table's format (that is, the table definition). The file bears the same name as the table, with an .frm extension.
https://dev.mysql.com/doc/internals/en/optimizer-code.html
This diagram shows the structure of the function handle_select() in /sql/sql_select.cc (the server code that handles a query): handle_select() mysql_select() JOIN::prepare() setup_fields() JOIN::optimize() /* optimizer is from here ... */ ...
https://dev.mysql.com/doc/internals/en/optimizer-definitions.html
This description uses a narrow definition: The optimizer is the set of routines which decide what execution path the DBMS should take for queries. MySQL changes these routines frequently, so you should compare what is said here with what's in the ...
https://dev.mysql.com/doc/internals/en/optimizer-index-merge-join-type.html
7.2.2.5.3 The range Optimizer For range queries, the MySQL optimizer builds a SEL_TREE object which represents a condition in this form: range_cond = (cond_key_1 AND cond_key_2 AND ... 7.2.2.5.1 Overview Index Merge is used when table condition can ...
https://dev.mysql.com/doc/internals/en/optimizer-order-by-clauses.html
In general, the optimizer will skip the sort procedure for the ORDER BY clause if it sees that the rows will be in order anyway. For the query: SELECT column1 FROM Table1 ORDER BY 'x'; the optimizer will throw out the ORDER BY clause. For the ...
https://dev.mysql.com/doc/internals/en/prepared-stored-procedure-execution.html
Execution of a stored procedure statement is similar to execution of a prepared statement. During execution of a stored procedure, THD::stmt_arena points to the permanent query arena of the stored procedure. This arena happens to be also the ...
https://dev.mysql.com/doc/internals/en/prepared-stored-statement-execution.html
A separate variable is needed because not all subqueries may get executed during the first execution of a statement. In order to call mysql_execute_command (the function that executes a statement) for a prepared statement and not damage its parse ...