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6 mar 2011 · To see the index for a specific table use SHOW INDEX: SHOW INDEX FROM yourtable; To see indexes for all tables within a specific schema you can use the STATISTICS table from INFORMATION_SCHEMA: SELECT DISTINCT TABLE_NAME, INDEX_NAME FROM INFORMATION_SCHEMA.STATISTICS WHERE TABLE_SCHEMA = 'your_schema';
To query the index information of a table, you use the SHOW INDEXES statement as follows: SHOW INDEXES FROM table_name; Code language: SQL (Structured Query Language) (sql) To get the index of a table, you specify the table name after the FROM keyword.
To find the rows matching a WHERE clause quickly.. To eliminate rows from consideration. If there is a choice between multiple indexes, MySQL normally uses the index that finds the smallest number of rows (the most selective index). If the table has a multiple-column index, any leftmost prefix of the index can be used by the optimizer to look up rows.
An estimate of the number of unique values in the index. To update this number, run ANALYZE TABLE or (for MyISAM tables) myisamchk -a . Cardinality is counted based on statistics stored as integers, so the value is not necessarily exact even for small tables.
4 sty 2023 · You can support more complex queries through indexes by understanding how MySQL chooses which indexes to use and when to use them. To learn more about that, refer to the MySQL documentation on indexes .
24 wrz 2008 · If you need to check if a index for a column exists as a database function, you can use/adopt this code. If you want to check if an index exists at all regardless of the position in a multi-column-index, then just delete the part AND SEQ_IN_INDEX = 1 .
2 lut 2024 · Today’s article educates on showing indexes for a table or a database in MySQL. We will learn how to get indexes from one or multiple tables within a database or all databases. We will use SHOW INDEXES, SHOW EXTENDED INDEX, SELECT DISTINCT commands, and the STATISTICS table to get the indexes.
