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https://dev.mysql.com/doc/refman/5.7/en/no-matching-rows.html
Select only those columns that are used in the WHERE clause. Issue a SELECT for the column that should have matched a row against the table that was last removed from the query. If you are comparing FLOAT or DOUBLE columns with numbers that have ...
https://dev.mysql.com/doc/refman/5.7/en/optimization-indexes.html
The best way to improve the performance of SELECT operations is to create indexes on one or more of the columns that are tested in the query. The index entries act like pointers to the table rows, allowing the query to quickly determine which rows ...Indexes also add to the cost of inserts, updates, and deletes because each index must be ...
https://dev.mysql.com/doc/refman/5.7/en/optimize-numeric.html
For unique IDs or other values that can be represented as either strings or numbers, prefer numeric columns to string columns. You also save code in your application because you can avoid parsing the text file to find line and column boundaries.
https://dev.mysql.com/doc/refman/5.7/en/partitioning-limitations-storage-engines.html
Partitioned InnoDB tables cannot have foreign key references, nor can they have columns referenced by foreign keys. All columns listed in the table's partitioning expression must be part of the primary key. If a user-partitioned NDB table is created ... The following limitations apply to the use of storage engines with user-defined partitioning of ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-subpartitions.html
However, due to the action of the PARTITION BY RANGE clause, the first 2 of these store only those records with a value less than 1990 in the purchased column. An exception to this is that SUBPARTITION BY KEY (unlike PARTITION BY KEY) does not ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-events-stages-current-table.html
The events_stages_current table has these columns: THREAD_ID, EVENT_ID The thread associated with the event and the thread current event number when the event starts. END_EVENT_ID This column is set to NULL when the event starts and updated to the ...The table stores one row per thread showing the current status of the thread's most recent monitored stage event, so there is no system variable for configuring the table ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-events-waits-current-table.html
The events_waits_current table has these columns: THREAD_ID, EVENT_ID The thread associated with the event and the thread current event number when the event starts. END_EVENT_ID This column is set to NULL when the event starts and updated to the ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-objects-summary-global-by-type-table.html
The objects_summary_global_by_type table has these grouping columns to indicate how the table aggregates events: OBJECT_TYPE, OBJECT_SCHEMA, and OBJECT_NAME. It resets the summary columns to zero rather than removing rows. The Performance Schema ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-setup-timers-table.html
The value can be any of the values in the performance_timers.TIMER_NAME column. The setup_timers table has these columns: NAME The type of instrument the timer is used for. The setup_timers.TIMER_NAME value can be changed to select a different timer. For an explanation of how event timing occurs, see Section 25.4.1, “Performance Schema Event ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-system-variables.html
performance_schema_max_sql_text_length Command-Line Format --performance-schema-max-sql-text-length=# System Variable performance_schema_max_sql_text_length Scope Global Dynamic No Type Integer Default Value 1024 Minimum Value 0 Maximum Value ...The ...