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https://dev.mysql.com/doc/internals/en/optimizer-joins-access-methods.html
It is recursive, so some input variables are labeled “so far” to indicate that they come from a previous iteration. Bad join choices can cause more damage than bad choices in single-table searches, so MySQL developers have spent proportionally ...
https://dev.mysql.com/doc/internals/en/running-mysql-test-run-out-of-source.html
It is a wrapper script that calls mysql-test-run.pl in the source directory and tells it where to look for the binaries, via the MTR_BINDIR environment variable. When building out of source (see Section 4.4.1, “Create the Build Directory”), use ...
https://dev.mysql.com/doc/internals/en/semi-sync-replication.html
To see of the master supports semi-sync replication run: SHOW VARIABLES LIKE 'rpl_semi_sync_master_enabled'; The slave requests semi-sync replication by sending: SET @rpl_semi_sync_slave = 1; which the master either responds with a OK_Packet if it ... In MySQL 5.5 replication can optionally be made semi-synchronous instead of the traditionally asynchronous ...
https://dev.mysql.com/doc/internals/en/subtest-case.html
Please use exact the formatting "# Bug#nnnnn <Title>" Example: # Bug#3671 Stored procedure crash if function has "set @variable=param" because it does not look nice to see so many different variants like "BUG #nnnnn", "bug #nnnnn - Title" often even ... Write a comment if the next subtest revealed a bug in ...
https://dev.mysql.com/doc/internals/en/syntax-debug-sync-values.html
The string to "assign" to the DEBUG_SYNC variable can contain: {RESET | <sync point name> TEST | <sync point name> CLEAR | <sync point name> {{SIGNAL <signal name> | WAIT_FOR <signal name> [TIMEOUT <seconds>] [NO_CLEAR_EVENT]} [EXECUTE <count>] &| ...This means that one of the sections separated by '&|' must be present or both of ...
https://dev.mysql.com/doc/internals/en/tracing-memory-usage.html
The optimizer_trace_max_mem_size variable sets a limit on the total amount of memory used by all currently remembered traces: If this limit is reached, the current trace isn't extended (so it will be incomplete), and the ...It is extended (with ...
https://dev.mysql.com/doc/internals/en/transformation-scalar-in.html
Item_ref is used to point to <left_expression cache>, because at the time of transformation we know only the address of the variable where the cache pointer will be stored. To rewrite a scalar IN subquery, the ...
https://dev.mysql.com/doc/internals/en/troubleshooting-cmake-code.html
Although there are advanced flags for cmake such as -debug-trycompile and --trace, a simple and efficient way to debug is to add MESSAGE("interesting variable=${variable_name}") to the interesting places in CMakeLists.txt.
https://dev.mysql.com/doc/internals/en/tuning-trace-purging.html
The more accurately those two variables are adjusted, the less memory is used. This is done with SET optimizer_trace_offset=<OFFSET>, optimizer_trace_limit=<LIMIT> where OFFSET is a signed integer, and LIMIT is a positive integer. The default for ...
https://dev.mysql.com/doc/internals/en/variation-of-storage-engine.html
Check your assumption with: ./myql-test-run.pl --mysqld="--default-storage-engine=<engine>" <test_case> Solution 2: Assign the storage engine to be used via $variable. Checks of the INFORMATION_SCHEMA The storage engines to be used for ...