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https://dev.mysql.com/doc/internals/en/join-buffer-size.html
Basic information about the join buffer cache: The size of each join buffer is determined by the value of the join_buffer_size system variable. This buffer is used only when the join is of type ALL or index (in other words, when no possible keys ...
https://dev.mysql.com/doc/internals/en/libmysql-directory.html
The files here are for producing MySQL as a library (for example, a Windows DLL). The idea is that, instead of producing separate mysql (client) and mysqld (server) programs, one produces a library. Instead of sending messages, the client part ...
https://dev.mysql.com/doc/internals/en/make-test-protocols-more-understandable.html
Please have the test write comments into the protocol if this makes the surrounding protocol content much more understandable. This is especially true for tests that do the following: Suppress the printing of SQL statements and result sets Work ...
https://dev.mysql.com/doc/internals/en/myisam-directory.html
They are: mi_cache.c --- for reading records from a cache mi_changed.c --- a single routine for setting a "changed" flag (very short) mi_check.c --- for checking and repairing tables. Can be used to exactly replay a set of changes to a table.
https://dev.mysql.com/doc/internals/en/myisampack.html
When starting to analyze the existing uncompressed data, it collects distinct column values up to a limit of 8KB. If there are more, it falls back to byte value compression for this column. This means also that myisampack may use different ...
https://dev.mysql.com/doc/internals/en/mysql-packet.html
If a MySQL client or server wants to send data, it: Splits the data into packets of size (224−1) bytes Prepends to each chunk a packet header Protocol::Packet Data between client and server is exchanged in packets of max 16MByte size. The number ...
https://dev.mysql.com/doc/internals/en/optimizer-constants-constant-tables.html
A MySQL constant is something more than a mere literal in the query. unique_not_null_column INT NOT NULL UNIQUE then this expression FROM Table1 ... These rules mean that a constant table has at most one row value. MySQL will evaluate a constant ...
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-joins-access-methods.html
Bad join choices can cause more damage than bad choices in single-table searches, so MySQL developers have spent proportionally more time making sure that the tables in a query are joined in an optimal order and that optimal access methods (often ...
https://dev.mysql.com/doc/internals/en/parsing-key-information.html
Many of the index methods pass a byte array named *key that identifies the index entry to be read in a standard format. Your storage engine will need to extract the information stored in the key and translate it into its internal index format to ...