Updated May 15, 2023
Introduction to Redshift indexes
The following article provides an outline for Redshift indexes. Redshift provides different types of functionality to the user, in which that index is one of the functionalities that are provided by Redshift. Basically, indexing is used to optimise the database as per user requirements. By using indexes in the database, we can reduce the disk I/O during the execution of the query to search particular values from the specified tables. Normally, an indexing technique we can include in a data structure is used to perform the quick operation, or we can say that it provides fast access of data from the database. Mainly we consider relational databases such as Oracle, SQL, etc.
Syntax
Basically, there are two ways to create the indexes in Redshift as follows.
First, we can create an index during the table creation as follows.
create table table_name (colm name 1 data type(size), colm name 2 data type(size), colm name N data type(size) specified constraint name(indexing) (specified colm name));
Explanation
In the above syntax, we use create table statement to create the table with index as shown in the above syntax. Here we specify the different column names with different data types and sizes as shown. At the end of syntax, we need to add the indexing parameter as per user requirements.
In a second way, we can use the alter command to add the index in the existing table as follows.
alter table specified table name add specified constraint name (specified colm name);
Explanation
In the above syntax, we use alter table command to add the index in the existing table; in this syntax, we need to pass the constraint name as well as the specified column name that we need to assign the index.
Above mentioned syntax depends on the user requirement that means as per user requirement, we can use any one of the syntaxes.
How do indexes work in Redshift?
Now let’s see how indexes work in Redshift as follows.
Being a columnar data set explicitly made for information warehousing, Redshift has an alternate treatment with regards to indexes. It doesn’t uphold standard records normally utilized in different data sets to cause inquiries to perform better. All types of keys work equally, such as distkey, sortkey; these keys can apply more than one column as per requirement. Basically, Redshift is supported to create the primary key, unique key, and foreign key. In any case, similar documentation expresses that these are instructive just and are not implemented. It is prescribed to utilize them if your information stacking measure guarantees their honesty, as they are utilized as arranging clues to advance question execution. In any case, you ought not to characterize them on the off chance that you question their legitimacy. For instance, if you don’t know whether the item name is truly extraordinary for a table, don’t make an interesting key limitation. In any case, on the off chance that you are sure, do make it so the information base motor can utilize it when executing your queries.
Basically, there are two ways to create the indexes in Redshift as follows.
In a first way, we can create the index at the time of table creation, in which we need to specify the constraint name as an index with a specified column name as shown in the above syntax.
In a second way, we can use the alter command, suppose we have an already created table, and we need to add the index into the table. At that time, we can use the alter table command to add the index.
Examples of Redshift indexes
Now let’s see different examples of indexes in Redshift for better understanding as follows.
Now let’s see the first way that is by using create table statements as follows.
create table product(
product_id int not null,
product_name varchar(255) not null,
product_cost decimal(15,2) not null,
primary key (product_id));
Explanation
In the above example, we use create table statement to create the index during table creation as shown; in this example, we created a product table with different attributes with different data types as shown. Here we add the primary key on the product_id column name as shown. The final output, or we can say the final result of the above statement, can illustrate by using the following screenshot.
Now let’s see how to add the sortkey as follows.
create table product1(
product_id int not null,
product_name varchar(255) not null,
product_cost decimal(15,2) not null)
sortkey (product_id, product_name);
Explanation
In the above example, we use create table statement to create the index during table creation as shown; in this example, we created a product_sample table with different attributes with different data types as shown. Here we add sortkey on product_id and product_name column shown. The final output, or we can say the final result of the above statement, can illustrate by using the following screenshot.
So in this way, we can use the distkey as per user requirements.
Now let’s see how we can use the alter table command to add the index in the existing table as follows.
Suppose we have a product table that we already created without any index, and we need to add the index into that table; at that time, we can use the following statement as follows.
alter table product add primary key(product_id);
Explanation
In the above example, we use the alter command to add the index into an existing table; here, we added the primary key on the product_id column as shown. The final output, or we can say the final result of the above statement, can illustrate by using the following screenshot.
So in this way, we can use alter to add the indexing with different constraints into an existing table as per user requirement.
As per user requirements, we can drop the index.
Conclusion
We hope from this article; you learn more about the Redshift indexes. From the above article, we have learned the basic concept as well as the syntax of the Redshift indexes, and we also see the different examples of the Redshift indexes. Furthermore, from this article, we learned how and when we use the Redshift indexes.
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This is a guide to Redshift indexes. Here we discuss the basic concept as well as the syntax of the Redshift indexes, and we also see the different examples. You may also have a look at the following articles to learn more –
