Redshift Best Way to Read Csv File

In this article, we are going to learn well-nigh Amazon Redshift and how to work with CSV files. Nosotros volition run into some of the means of data import into the Redshift cluster from S3 bucket besides every bit data consign from Redshift to an S3 bucket. This article is written for beginners and users of intermediate level and assumes that yous have some basic knowledge of AWS and Python.

Table Of Contents

1. How to Export and Import CSV Files into Redshift in Different Ways
2. How to Load CSV File into Amazon Redshift
   • Load Data from Amazon S3 to Redshift, Using COPY Command
   • Auto Import Data into Amazon Redshift with Skyvia
   • Load Information from S3 to Redshift, Using Python
3. How to Unload CSV from Redshift
   • Export Information from Redshift, Using UNLOAD Command
   • Consign Data from Redshift to CSV by Schedule, Using Skyvia
4. Conclusion

How to Export and Import CSV Files into Redshift in Dissimilar Ways

Modern businesses tend to generate a lot of information every mean solar day. Once the data is generated, information technology is required to exist stored and analyzed so that strategic business decisions tin can be made based on the insights gained. In today'due south world, where more and more organizations are shifting their infrastructure to the cloud, Amazon Web Services, also known equally AWS, provides a fully managed cloud data warehousing solution, which is Amazon Redshift.

Amazon Redshift is a fully managed data warehouse on the deject. It supports Massively Parallel Processing Architecture (MPP), which allows users to process information parallelly. It allows users to load and transform information within Redshift and then make it bachelor for the Business Intelligence tools.

CSV files are a very mutual and standard format of apartment files in which columns and values are separated past a comma. Reading and storing data in CSV files are very simple, they take been used in the industry for over a few decades now. Y'all can see a sample CSV file below.

In this commodity, you will learn various ways of data import/consign from CSV to Redshift and vice versa.

How to Load CSV File into Amazon Redshift

Since CSV is i of the most popular forms of dealing with data in flat files, there are many tools and options to piece of work with such CSV files. As such, in that location are different ways of how CSV files can be imported and exported from Redshift likewise. You will learn about these methods in the later section as follows.

Load Information from Amazon S3 to Redshift, Using COPY Command

I of the most common ways to import data from a CSV to Redshift is by using the native COPY command. Redshift provides a COPY control using which yous tin directly import data from your apartment files to your Redshift Data warehouse. For this, the CSV file needs to be stored within an S3 bucket in AWS. S3 is abbreviated for Simple Storage Service, where you lot can store whatever type of files. The post-obit steps need to be performed in order to import data from a CSV to Redshift using the Re-create command:

1. Create the schema on Amazon Redshift.
2. Load the CSV file to Amazon S3 bucket using AWS CLI or the web console.
3. Import the CSV file to Redshift using the COPY control.
   • Generate AWS Access and Cloak-and-dagger Key in gild to use the Copy control.

In the next section, you volition come across a few examples of using the Redshift Copy command.

Redshift Copy Command Examples

Get-go y'all can create a cluster in Redshift and second create the schema every bit per your requirements. I will employ the aforementioned sample CSV schema that you've seen in the previous department. In social club to create the schema in Redshift, you can merely create a table with the post-obit command.

The next stride is to load information into an S3 saucepan which can be done by either using the AWS CLI or the web console. If your file is big, you should consider using the AWS CLI.

At present when the CSV file is in S3, y'all can use the Re-create command in Redshift to import the CSV file. Head over to your Redshift query window and blazon in the following control.

COPY table_name FROM 'path_to_csv_in_s3' credentials  'aws_access_key_id=YOUR_ACCESS_KEY;aws_secret_access_key=YOUR_ACCESS_SECRET_KEY' CSV;

In one case the Copy command has been executed successfully, you receive the output equally in the above screen print. Now, you can query your information using a simple select argument as follows.

Sometimes, it might be that yous do non want to import all the columns from the CSV file into your Redshift tabular array. In that case, y'all can specify the columns while using the Re-create control, and information simply from those columns will be imported into Redshift.

As you can see in the above figure, you can explicitly mention names of the commands that demand to be imported to the Redshift table.

Redshift Re-create Control to Ignore Header from Table

Another of import scenario while importing data from CSV to Redshift using the Copy control is that your CSV file might contain a header and you practise not want to import information technology. In other words, you desire to ignore the header from the CSV file from being imported into the Redshift tabular array. In such a case, yous demand to add together a specific parameter IGNOREHEADER to the Re-create command and specify the number of lines to exist ignored. Usually, if yous just desire to ignore the header, which is the first line of the CSV file, you demand to provide the number as ane.

Auto Import Data into Amazon Redshift with Skyvia

Skyvia is a third-party cloud-based solution, which helps to automate data import from CSV to Amazon Redshift painlessly on a recurring basis. To start the process, simply sign up to the platform.

To accomplish the process in Skyvia, follow these three unproblematic steps:

1. Gear up upwardly an Amazon Redshift connection;
2. Configure information import and mapping settings betwixt CSV file and Redshift;
3. Schedule data migration

Connection Setup

Select Amazon Redshift amidst the list of data warehouses supported by Skyvia. In the opened Redshift connection window, enter the required parameters, which are Server, Port, User ID, Countersign and Database. You lot likewise need to click Advanced Settings and set parameters for connecting to Amazon S3 storage service. Amidst them are S3 region to use and either AWS Security Token or AWS Access Central ID and AWS Secret Key. After, bank check whether the connection is successful and click Create. You lot have completed the first step and continued to Amazon Redshift.

Bundle Settings and Mapping

• Open an import package, select CSV as source and Redshift connectedness as target.
• Proceed with calculation a task to the package. You are free to add as many tasks as you need. Skyvia allows performing several import tasks in one package and, thus, importing several CSV files to Redshift in a single import performance.
  • In the task editor, upload a prepared CSV file. You lot are able to upload both CSV files from your PC or from a file storage service like Dropbox, Box, FTP, etc. As soon as you uploaded a CSV file, Skyvia displays a list of detected columns and allows you to explicitly specify cavalcade data types.
  • Adjacent, select an object in Redshift the data volition exist loaded to and choose an functioning type.
  • Columns with the aforementioned names in CSV and Redshift are mapped automatically. Map all other required source columns to target ones, using expressions, constants, lookups, etc. and save a chore.
• In the package, you volition see a saved task. Add together another task in instance yous have another CSV file. Read more than near CSV import to Redshift.

Job Automation

Automate uninterrupted information motion from CSV to Redshift on a regular footing by setting schedule for your import package. Click Schedule and enter all required parameters in the Schedule window.

For the first fourth dimension we recommend that you run your package manually to check how successful your package has been executed. If some of your columns in source and target are mapped incorrectly, y'all will see errors in your runs and will be able to update mapping settings. Moreover, Skyvia can send error notifications to your email.

Schedule your CSV data export and import to deject apps or databases without coding

Load Data from S3 to Redshift, Using Python

Python is one of the nearly popular programming languages in the modern data world. Almost every service on AWS is supported with the python framework, and you can easily build your integrations with it. Nosotros can use Python to build and connect to these services using libraries that are already bachelor. In the following section, you will acquire more well-nigh loading data from S3 to Redshift using python.

In order to be able to connect to Redshift using python, you need to use a library – "psycopg2". This library tin can be installed by running the command every bit follows.

Once the library is installed, you lot tin can start with your python program. Y'all need to import the library into your program as follows and then prepare the connexion object. The connection object is prepared by providing the hostname of the Redshift cluster, the port on which it is running, the name of the database and the credentials to connect to the database.

Once the connexion is established, you lot can create a cursor that will be used while executing the query on the Redshift cluster.

In the side by side stride, you demand to provide the query that needs to be executed to load the data to Redshift from S3. This is the aforementioned query that you have executed on Redshift previously.

In one case the query is prepared, the side by side step is to execute information technology. You can execute and commit the query by using the following commands:

cursor.execute(query) conn.commit()

Now, you lot tin can go back to your Redshift cluster and check if the data has been copied from the S3 bucket to the Redshift cluster.

How to Unload CSV from Redshift

Like loading data from external files into Redshift, there is too an option to export data out of Redshift.

Export Data from Redshift, Using UNLOAD Command

Loding data out of Amazon Redshift can be done using UNLOAD command. You can simply select the data from Redshift and then provide a valid path to your S3 saucepan to drift information to. You can too filter the information in the select statement then export your data as required. Once the query is ready, use the post-obit command to unload data from Redshift to S3:

UNLOAD ('SELECT * FROM exam.sample_csv') TO 's3://csv-redshift-221/Unload_' credentials 'aws_access_key_id=AKIA46SFIWN5JG7KM7O3;aws_secret_access_key=d4qfQNq4zYL39jcy4r4IWAxn4qPz4j8JgULvKa2d' CSV;

Once the UNLOAD command is executed successfully, you can view the new file created nether the S3 bucket.

The file is now available in the S3 bucket which can exist downloaded and opened by any text editor.

Export Data from Redshift to CSV by Schedule, Using Skyvia

With Skyvia, you can consign data from Redshift the same way as you imported data to it. For data migration from Redshift, sign in to Skyvia, open an consign packet, select Redshift every bit source, filter information you want to export, configure other packet settings, create and run the bundle. Don't forget to gear up a schedule for your packet. Read more about Redshift export to CSV.

Conclusion

In this article, we've described several ways to import CSV to Redshift and vice versa. For those users who demand data import/export from CSV on schedule, Skyvia volition be of help. For more data, contact Skyvia support team.

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Source: https://skyvia.com/blog/how-to-export-and-import-csv-files-into-redshift-in-several-different-ways

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