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If you're using LIKE, indexing engines will typically help with your read speed up to the first "%". In other words, if you're SELECTing WHERE column LIKE 'foo%bar%', the database will use the index to find all the rows where column starts with "foo", and then need to scan that intermediate rowset to find the subset that contains "bar". SELECT ...
28 lut 2014 · Create a compound btree index on monitorid + starttime columns. This index can give the best results for queries which use WHERE starttime > X AND monitorid = Y clause. CREATE INDEX name ON tablename( monitorid + starttime ) monitorid must be a leading column in this index, otherwise the index will be not usable.
23 wrz 2024 · Analyze index usage: MySQL tools like EXPLAIN and other utilities help you identify which indexes are being used, how often they are accessed, and their effectiveness. By analyzing this information, you can locate redundant, unused, or inefficient indexes and make informed decisions about index maintenance, such as dropping or rebuilding ...
10.3.1 How MySQL Uses Indexes. Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine ...
1 wrz 2016 · Many real-world database tables have many rows with DATETIME OR TIMESTAMP column values spanning a lot of time, including years or even decades. Often it's necessary to use a WHERE clause to retrieve some subset of that timespan.
2 paź 2023 · Before rushing to create a new index to speed up your query, it’s vital to have a comprehensive understanding of how MySQL indexing works, the different types of indexes, and the...
3 paź 2010 · All MySQL data types can be indexed. Although it can be tempting to create an indexes for every possible column used in a query, unnecessary indexes waste space and waste time for MySQL to determine which indexes to use.
