Why SQL Indexing is Important?
Indexing is an important topic when considering advanced MySQL, although most people know about its definition and usage they don’t understand when and where to use it to change the efficiency of our queries or stored procedures by a huge margin.
Here are some scenarios along with their explanation related to Indexing:
- When executing a query on a table having huge data ( > 100000 rows ), MySQL performs a full table scan which takes much time and the server usually gets timed out. To avoid this always check the explain option for the query within MySQL which tells us about the state of execution. It shows which columns are being used and whether it will be a threat to huge data. On basis of the columns repeated in a similar order in condition.
- The order of the index is of huge importance as we can use the saitions, we can create an index for them in the same order to maximize the speed of the query. me index in many scenarios. Using only one index we can utilize it in more than one query which different conditions. like for example, in a query, we make a join with a table based on customer_id wards we also join another join based on customer_id and order_date. Then we can simply create a single index by the order of customer_id, order_date which would be used in both cases. This also saves storage.
- We should also be careful to not make an index for each query as creating indexes also take storage and when the amount of data is huge it will create a problem. Therefore, it’s important to carefully consider which columns to index based on the needs of your application. In general, it’s a good practice to only create indexes on columns that are frequently used in queries and to avoid creating indexes on columns that are rarely used. It’s also a good idea to periodically review the indexes in your database and remove any that are no longer needed.
- Indexes can also improve performance when used in conjunction with sorting and grouping operations. For example, if you frequently sort or group data based on a particular column, creating an index on that column can greatly improve performance. The index allows MySQL to quickly access and sort or group the data, rather than having to perform a full table scan.
- In some cases, MySQL may not use an index even if one exists. This can happen if the query optimizer determines that a full table scan is faster than using the index.
SQL Indexes
An index is a schema object. It is used by the server to speed up the retrieval of rows by using a pointer. It can reduce disk I/O(input/output) by using a rapid path access method to locate data quickly.
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