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https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-wait-summary-tables.html
The table_io_waits_summary_by_table table has these grouping columns to indicate how the table aggregates events: OBJECT_TYPE, OBJECT_SCHEMA, and OBJECT_NAME. These columns have the same meaning as in the events_waits_current table. As indicated in ... The following sections describe the table I/O and lock wait summary tables: table_io_waits_summary_by_index_usage: Table I/O waits per index table_io_waits_summary_by_table: Table I/O waits per table table_lock_waits_summary_by_table: Table lock waits per table 29.12.20.8.1 The table_io_waits_summary_by_table Table The table_io_waits_summary_by_table table aggregates all table I/O wait events, as generated by the wait/io/table/sql/handler ...
https://dev.mysql.com/doc/refman/8.4/en/timestamp-initialization.html
TIMESTAMP and DATETIME columns can be automatically initialized and updated to the current date and time (that is, the current timestamp). For any TIMESTAMP or DATETIME column in a table, you can assign the current timestamp as the default value, ...Any of the synonyms for CURRENT_TIMESTAMP have the same meaning as ...
https://dev.mysql.com/doc/refman/8.4/en/json.html
The JSON data type provides these advantages over storing JSON-format strings in a string column: Automatic validation of JSON documents stored in JSON columns. JSON documents stored in JSON columns are converted to an internal format that permits ...When the server later must read a JSON value stored in this binary format, the value need not be parsed from a text ...
https://dev.mysql.com/doc/refman/8.4/en/storage-requirements.html
Table data might be compressed, either for a column or an entire row, complicating the calculation of storage requirements for a table or column. This figure excludes BLOB or TEXT columns, which contribute only 9 to 12 bytes toward this size. For ...
https://dev.mysql.com/doc/ndbapi/en/ndb-examples-recattr-vs-ndbrecord.html
This example illustrates the key differences between the old-style NdbRecAttr API and the newer approach using NdbRecord when performing some common tasks in an NDB API application. The source code can be found can be found in the file ...
https://dev.mysql.com/doc/refman/8.4/en/join.html
Such subqueries must include an alias to give the subquery result a table name, and may optionally include a list of table column names in parentheses. If you mix comma joins with the other join types when there is a join condition, an error of the ... MySQL supports the following JOIN syntax for the table_references part of SELECT statements and multiple-table DELETE and UPDATE statements: table_references: escaped_table_reference [, escaped_table_reference] ...
https://dev.mysql.com/doc/refman/8.4/en/select.html
} export_options: [{FIELDS | COLUMNS} [TERMINATED BY 'string'] [[OPTIONALLY] ENCLOSED BY 'char'] [ESCAPED BY 'char'] ] [LINES [STARTING BY 'string'] [TERMINATED BY 'string'] ] SELECT is used to retrieve rows selected from one or more tables, and can ... SELECT [ALL | DISTINCT | DISTINCTROW ] [HIGH_PRIORITY] [STRAIGHT_JOIN] [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT] [SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS] select_expr [, select_expr] ...
https://dev.mysql.com/doc/refman/8.4/en/string-type-syntax.html
In some cases, MySQL may change a string column to a type different from that given in a CREATE TABLE or ALTER TABLE statement. For definitions of character string columns (CHAR, VARCHAR, and the TEXT types), MySQL interprets length specifications ... The string data types are CHAR, VARCHAR, BINARY, VARBINARY, BLOB, TEXT, ENUM, and ...
https://dev.mysql.com/doc/refman/8.4/en/create-table-ndb-comment-options.html
NDB_COLUMN Options NDB_TABLE Options It is possible to set a number of options specific to NDB Cluster in the table comment or column comments of an NDB table. NDB_COLUMN can be used in a column comment to set the size of the blob parts table ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-statement-summary-tables.html
Each statement summary table has one or more grouping columns to indicate how the table aggregates events. Event names refer to names of event instruments in the setup_instruments table: events_statements_summary_by_account_by_event_name has ... The ...