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https://dev.mysql.com/doc/refman/8.0/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/8.0/en/group-by-optimization.html
For example, with c1 VARCHAR(20), INDEX (c1(10)), the index uses only a prefix of c1 values and cannot be used for Loose Index Scan. The most general way to satisfy a GROUP BY clause is to scan the whole table and create a new temporary table where ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-ft-index-cache-table.html
The INNODB_FT_INDEX_CACHE table provides token information about newly inserted rows in a FULLTEXT index. Before querying it, set the value of the innodb_ft_aux_table system variable to the name (including the database name) of the table that ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-ft-index-table-table.html
The INNODB_FT_INDEX_TABLE table provides information about the inverted index used to process text searches against the FULLTEXT index of an InnoDB table. Before querying it, set the value of the innodb_ft_aux_table system variable to the name ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-innodb-virtual-table.html
The INNODB_VIRTUAL table provides metadata about InnoDB virtual generated columns and columns upon which virtual generated columns are based. A row appears in the INNODB_VIRTUAL table for each column upon which a virtual generated column is based.
https://dev.mysql.com/doc/refman/8.0/en/information-schema-introduction.html
Character Set Considerations The definition for character columns (for example, TABLES.TABLE_NAME) is generally VARCHAR(N) CHARACTER SET utf8mb3 where N is at least 64. INFORMATION_SCHEMA provides access to database metadata, information about the ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-partitions-table.html
Each row in this table corresponds to an individual partition or subpartition of a partitioned table. The PARTITIONS table has these columns: TABLE_CATALOG The name of the catalog to which the table belongs. TABLE_SCHEMA The name of the schema ...
https://dev.mysql.com/doc/refman/8.0/en/information-schema-statistics-table.html
However, prefix lengths for index specifications in CREATE TABLE, ALTER TABLE, and CREATE INDEX statements are interpreted as number of characters for nonbinary string types (CHAR, VARCHAR, TEXT) and number of bytes for binary string types (BINARY, ...The information_schema_stats_expiry system variable defines the period of time before cached table statistics ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-auto-increment-handling.html
To make this clear, consider an example that uses this table: CREATE TABLE t1 ( c1 INT(11) NOT NULL AUTO_INCREMENT, c2 VARCHAR(10) DEFAULT NULL, PRIMARY KEY (c1) ) ENGINE=InnoDB; Suppose that there are two transactions running, each inserting rows ... InnoDB provides a configurable locking mechanism that can significantly improve scalability and performance of SQL statements that add rows to tables with AUTO_INCREMENT ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-compression-tuning.html
Character strings often compress well, whether defined in CHAR, VARCHAR, TEXT or BLOB columns. Most often, the internal optimizations described in InnoDB Data Storage and Compression ensure that the system runs well with compressed data. However, ...