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https://dev.mysql.com/doc/internals/en/row-order-within-result-sets.html
Please keep in mind that the row order within a significant number of result sets depends on storage engine properties and in worst cases the current load (NDB!, partitioning?, parallel query?) on the testing box. Either use --sorted_result SELECT ...
https://dev.mysql.com/doc/internals/en/select-subquery.html
In expressions, subqueries (that is, subselects) are represented by Item inherited from Item_subselect. To hide difference in performing single SELECTs and UNIONs, Item_subselect uses two different engines, which provide uniform interface for ...
https://dev.mysql.com/doc/internals/en/select-union.html
We will need this object to store in every JOIN structure link on it, but we have not (yet) temporary table structure. Allocate JOIN structures and execute JOIN::prepare() for every SELECT to get full information about types of elements of SELECT ...
https://dev.mysql.com/doc/internals/en/store-lock.html
If TL_UNLOCK is set If we are not doing a LOCK TABLE or DISCARD/IMPORT TABLESPACE, then allow multiple writers */ if ((lock_type >= TL_WRITE_CONCURRENT_INSERT && lock_type <= TL_WRITE) && !thd->in_lock_tables && !thd->tablespace_op) lock_type = ...
https://dev.mysql.com/doc/internals/en/threads.html
The other reads queries from the relay log and executes them. Threads in mysqld can run at four different priorities, defined in mysql_priv.h: #define INTERRUPT_PRIOR 10 #define CONNECT_PRIOR 9 #define WAIT_PRIOR 8 #define QUERY_PRIOR 6 Some ...
https://dev.mysql.com/doc/internals/en/transformation-scalar-in.html
To rewrite a scalar IN subquery, the Item_in_subselect::single_value_transformer method is used. The scalar IN subquery will be replaced with an Item_in_optimizer item. On a value request (one of val, val_int, or val_str methods) it evaluates the ...
https://dev.mysql.com/doc/internals/en/uncompressed-payload.html
For small packets it may be to costly to compress the packet: compressing the packet may lead to more data and sending the data uncompressed CPU overhead may be not worth to compress the data Tip Usually payloads less than 50 bytes ...
https://dev.mysql.com/doc/internals/en/variation-of-protocol-option.html
It is usual to run tests with and without the mysql-test-run.pl startup option "--ps-protocol". And there are also attempts of System QA to run the other protocols. Effect of the "--ps-protocol" option: mysqltest will run as many SQL statements as ...
https://dev.mysql.com/doc/internals/en/x-protocol-implementation-implementation-notes.html
Topics in this section: Client Server Client and Server implementations of the protocol should make use of the following: vectorized IO pipelining to reduce the latency and CPU usage. Client Out-of-Band Messages The client should decode the ...
https://dev.mysql.com/doc/mysql-installer/en/server-logging-options.html
This step is available if the Show Advanced Configuration check box was selected during the Type and Networking step. To enable this step now, click Back to return to the Type and Networking step and select the check box. Advanced configuration ...