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https://dev.mysql.com/doc/internals/en/optimizer-index-merge-join-type.html
MySQL creates a cond_key_i condition for each of the usable keys. 7.2.2.5.1 Overview Index Merge is used when table condition can be converted to form: cond_1 OR cond_2 ... OR cond_N The conditions for conversion are that each cond_i can be used ...
https://dev.mysql.com/doc/internals/en/prepared-stored-procedure-execution.html
This arena happens to be also the permanent query arena of every instruction of the procedure, as the parser creates all instructions in the same arena. Execution of a stored procedure statement is similar to execution of a prepared statement.
https://dev.mysql.com/doc/internals/en/prepared-stored.html
The role of the parser is to create a set of objects to represent the query. Creation of an execution plan, including evaluation of an order of joins and initialization of methods to access the used tables. Let us start with a general description ...
https://dev.mysql.com/doc/internals/en/replication-not-guaranteed.html
(P-exception-federated) If a table uses a federated table on the master, then TODO (P-exception-table-definition) If a CREATE TABLE uses a DATA DIRECTORY or INDEX DIRECTORY clause, then the table may not be correctly replicated. There are some ...
https://dev.mysql.com/doc/internals/en/running-mysql-test-run-out-of-source.html
When building out of source (see Section 4.4.1, “Create the Build Directory”), use mysql-test-run.pl in the mysql-test directory under the build directory. It is a wrapper script that calls mysql-test-run.pl in the source directory and tells it ...
https://dev.mysql.com/doc/internals/en/select-steps.html
Every select is performed in these base steps: JOIN::prepare Initialization and linking JOIN structure to st_select_lex. fix_fields() for all items (after fix_fields(), we know everything about item).
https://dev.mysql.com/doc/internals/en/select-structure.html
At the time of creating or performing any JOIN::* operation, LEX::current_select points to an appropriate SELECT_LEX. There are two structures that describe selects: st_select_lex (SELECT_LEX) for representing SELECT itself st_select_lex_unit ...
https://dev.mysql.com/doc/internals/en/select-subquery.html
The engine will be created at the time Item_subselect is constructed (Item_subselect::init method). In expressions, subqueries (that is, subselects) are represented by Item inherited from Item_subselect. To hide difference in performing single ...
https://dev.mysql.com/doc/internals/en/store-lock.html
Synopsis virtual THR_LOCK_DATA ** store_lock ( thd, to, lock_type); THD * thd ; THR_LOCK_DATA ** to ; enum thr_lock_type lock_type ; Description This is the store_lock method. The idea with handler::store_lock() is the following: The statement ...
https://dev.mysql.com/doc/internals/en/strings-directory.html
Many of the files in this subdirectory are equivalent to well-known functions that appear in most C string libraries. On the other hand, some of the files are MySQL additions or improvements. Often the MySQL changes are attempts to optimize the ...