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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.
MySQL uses indexes to rapidly locate rows with specific column values. Without an index, MySQL must scan the entire table to find the relevant rows. The larger the table, the slower the search becomes.
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.
SHOW [EXTENDED] {INDEX | INDEXES | KEYS} {FROM | IN} tbl_name [{FROM | IN} db_name] [WHERE expr] SHOW INDEX returns table index information. The format resembles that of the SQLStatistics call in ODBC. This statement requires some privilege for any column in the table.
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 .
26 lip 2024 · MySQL indexes are data structures that speed up the retrieval of rows from a database table by allowing MySQL to quickly locate the data without scanning the entire table. How many indexes are there in MySQL? MySQL supports several types of indexes, including: Primary Index ; Unique Index ; Full-Text Index ; Composite Index; Spatial Index ...
