I have never worked in that area and never used that index.
This index is meant for geometric values, and it’s used for map and GIS-related purposes. The advantage of a primary key is that MySQL sorts the data in a way that matches the key, and it’s the fastest key in terms of select performance. So in our example, if we put a primary key on the column Name, we can only have one name ‘John,’ but we can also have ‘Beth’ and ‘Karen.’ The primary key can span multiple columns, which guarantees that the data is unique. MySQL index types: What is a Primary key?Įvery table should have a primary key (unless you know what you are doing). It’s essential to choose the right one for what we need. There are several types of indexes in MySQL, and each has its use case and performance. Just like the index in a phone book (if you remember those), you’d search the Name, and it will point you to the page where that Name is. Indexes allow for fast retrieval of data. It takes about 5 minutes to get our data.
MYSQL OPTIMIZER SETTINGS FULL
For debugging purposes, we need to do a full table scan once in a while. That would be crazy slow.įor example, we have a table with 300 million keywords. Think of a table with 1,000,000,000 rows (we have some of those in our data store), and every MySQL query will have to scan the entirety of the data. The reason is that MySQL will need to scan every row in the table and compare Name to ‘John.’ It will only exit once it found it, or it didn’t find anything.Ĭhecking every row in the table is called a full table scan, which has zero performance. That would work great as long as we have a small amount of data, but the MySQL query speed will decrease when our table grows. We want to get the age of John, so we make a simple selection: Select Age from People where Name='John' Let’s say we have a simple table schema: CREATE TABLE People (
To understand why indexes are needed, we need to know how MySQL gets the data. Select and full table scan (slow slow slow) If you are a MySQL professional, you can skip this part, as you are probably aware of what an Index is and how it is used. Create an indexĪn index is the heart of every SQL based relational database, create the right one, and performance will be good. If there’s enough memory, it can cache MySQL raw files and skew the measurement. Another option is to see the time reported by MySQL to perform each query (BTW SQL stands for Standard Query Language, in case it wasn’t clear by now), but you need to ensure that the results were not served from the query cache.Īnother possible caching related “issue” that may affect the measurement is OS cache. Measuring MySQL performance was also covered in the previous article. Look at this section in our previous article ( Buy a fast server Look at items four through six) a fast summary is that you shouldn’t use mechanical hard drives, and a dedicated server is faster than a cloud instance.
Server and hardware selection for MySQL server database.
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