How to use indexed datetime column in MySQL?

How to use indexed datetime column in MySQL?

MyISAM only uses index caching. Since the query should not touch the .MYD file, you should use a slightly bigger MyISAM Key Buffer. Give it a Try !!! Change your date column type to an integer. Store the date as a Unix date in integer. Timestamp Is a lot larger than an int. You’d get some bang out of that.

Is it good idea to index datetime field in…?

MySQL recommends using indexes for a variety of reasons including elimination of rows between conditions: http://dev.mysql.com/doc/refman/5.0/en/mysql-indexes.html This makes your datetime column an excellent candidate for an index if you are going to be using it in conditions frequently in queries.

Why is Index on date field and month ( ) year?

The problem is the optimization of the query. When you use YEAR () and MONTH () on a date column, the column is a function of an argument. That means that the compiler would have a lot of information about the function in order to optimize it using an index scan or index lookup.

When to use year and month on date column?

When you use YEAR () and MONTH () on a date column, the column is a function of an argument. That means that the compiler would have a lot of information about the function in order to optimize it using an index scan or index lookup.

Why is indexing date a bad choice in MySQL?

I figured that indexing date will give me “bad” cardinality and thus MySQL won’t use it. http is also a bad choice as there are only about 20 different possible values. Thanks for you help! and used his query, but it performed equally bad.

How to fix MySQL between two datetimes?

NOTE If I remove the 00:00:00 and 23:59:59 then it uses index it only goes through 1 row but I need to select all data for entire day starting at 00:00 and ending at 23:59. Please help me restructure this query to fix this issue or suggest any possible solutions. thank you.

Why is an index not used in MySQL?

It’s inefficient because it applies a function — DATE () — to the values of a column. That means MySQL must examine each value of x, and an index cannot be used. This selects a range of values of x lying anywhere on the day in question, up until but not including (hence <) midnight on the next day.

How does an index scan work in MySQL?

If the table has an index on the x column, then the database server can perform a range scan on the index. That means it can quickly find the first relevant value of x, and then scan the index sequentially until it finds the last relevant value. An index range scan is much more efficient than the full table scan required by DATE (x) = ‘2016-09-01.

Which is index would be clever in MySQL?

The above mentioned query takes about 0.6-1.6 seconds to run. Which index would be clever? I figured that indexing date will give me “bad” cardinality and thus MySQL won’t use it. http is also a bad choice as there are only about 20 different possible values.

Why is the Index on the left side of the equal sign?

The added index: The WHERE should not have a function on both sides of the equal sign. Having date on the left side of the equals sign makes it easier for the Query Optimizer to use an index against it. I suggest this order of columns because the date entries would all be contiguous in the index.