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https://dev.mysql.com/doc/refman/5.7/en/replication-options-replica.html
This section explains the server options and system variables that apply to replicas and contains the following: Startup Options for Replicas Options for Logging Replica Status to Tables System Variables Used on Replicas Specify the options either ...
https://dev.mysql.com/doc/refman/5.7/en/date-and-time-type-syntax.html
Also, any TIMESTAMP not explicitly declared as NOT NULL permits NULL values. You can also set any TIMESTAMP column to the current date and time by assigning it a NULL value, unless it has been defined with the NULL attribute to permit NULL values.
https://dev.mysql.com/doc/refman/5.7/en/group-by-handling.html
The query is invalid if name is not a primary key of t or a unique NOT NULL column. SQL-92 and earlier does not permit queries for which the select list, HAVING condition, or ORDER BY list refer to nonaggregated columns that are not named in the ...
https://dev.mysql.com/doc/refman/5.7/en/optimizing-myisam-bulk-data-loading.html
These performance tips supplement the general guidelines for fast inserts in Section 8.2.4.1, “Optimizing INSERT Statements”. For a MyISAM table, you can use concurrent inserts to add rows at the same time that SELECT statements are running, if ...
https://dev.mysql.com/doc/refman/5.7/en/timestamp-initialization.html
In addition, if the explicit_defaults_for_timestamp system variable is disabled, you can initialize or update any TIMESTAMP (but not DATETIME) column to the current date and time by assigning it a NULL value, unless it has been defined with the NULL ... TIMESTAMP and DATETIME columns can be automatically initializated and updated to the current date and time (that is, the current ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-statement-digests.html
If the table becomes full, the Performance Schema groups statements that have SCHEMA_NAME and DIGEST values not matching existing values in the table in a special row with SCHEMA_NAME and DIGEST set to NULL. The MySQL server is capable of ...
https://dev.mysql.com/doc/refman/5.7/en/optimizer-hints.html
One means of control over optimizer strategies is to set the optimizer_switch system variable (see Section 8.9.2, “Switchable Optimizations”). Changes to this variable affect execution of all subsequent queries; to affect one query differently ...
https://dev.mysql.com/doc/refman/5.7/en/optimizer-issues.html
MySQL uses a cost-based optimizer to determine the best way to resolve a query. In many cases, MySQL can calculate the best possible query plan, but sometimes MySQL does not have enough information about the data at hand and has to make ...
https://dev.mysql.com/doc/refman/5.7/en/table-scan-avoidance.html
The output from EXPLAIN shows ALL in the type column when MySQL uses a full table scan to resolve a query. This usually happens under the following conditions: The table is so small that it is faster to perform a table scan than to bother with a ...
https://dev.mysql.com/doc/refman/5.7/en/using-system-variables.html
The MySQL server maintains many system variables that configure its operation. Section 5.1.7, “Server System Variables”, describes the meaning of these variables. System variables can be set at server startup using options on the command line ...