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https://dev.mysql.com/doc/refman/8.4/en/counting-rows.html
Counting the total number of animals you have is the same question as “How many rows are in the pet table?” because there is one record per pet. COUNT(*) counts the number of rows, so the query to count your animals looks like this: mysql> ...
https://dev.mysql.com/doc/refman/8.4/en/engine-condition-pushdown-optimization.html
This has the potential to improve performance of queries by a significant margin. This optimization improves the efficiency of direct comparisons between a nonindexed column and a constant. In such cases, the condition is “pushed down” to the ...
https://dev.mysql.com/doc/refman/8.4/en/function-optimization.html
A function is nondeterministic if, given fixed values for its arguments, it can return different results for different invocations. If a function is tagged nondeterministic, a reference to it in a WHERE clause is evaluated for every row (when ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-consistent-read.html
You can get a fresher snapshot for your queries by committing the current transaction and after that issuing new queries. A consistent read means that InnoDB uses multi-versioning to present to a query a snapshot of the database at a point in time.
https://dev.mysql.com/doc/refman/8.4/en/innodb-statistics-estimation.html
Enabling innodb_stats_on_metadata may reduce access speed for schemas that have a large number of tables or indexes, and reduce stability of execution plans for queries that involve InnoDB tables. See Section 10.2.1.23, “Avoiding Full Table ...
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 ...
https://dev.mysql.com/doc/refman/8.4/en/ldml-collation-example.html
To add a UCA collation for a Unicode character set without recompiling MySQL, use the following procedure. If you are unfamiliar with the LDML rules used to describe the collation's sort characteristics, see Section 12.14.4.2, “LDML Syntax ...
https://dev.mysql.com/doc/refman/8.4/en/monitor-mysql-memory-use.html
In this example, memory instrument data is queried in the Performance Schema memory_summary_global_by_event_name table, which summarizes data by EVENT_NAME. The following example demonstrates how to use Performance Schema and sys schema to monitor ...
https://dev.mysql.com/doc/refman/8.4/en/multiple-tables.html
The pet table keeps track of which pets you have. If you want to record other information about them, such as events in their lives like visits to the vet or when litters are born, you need another table. What should this table look like? It needs ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-sql-statements.html
However, you can use LIKE to filter queries against the Information Schema ENGINES table, as discussed in the next item. This section discusses several SQL statements that can prove useful in managing and monitoring a MySQL server that is connected ...