Creating tables by importing CSV files from AWS S3

You can create tables in Hue by importing CSV files stored in S3 buckets. Hue automatically detects the schema and the column types, thus helping you to create tables without using the CREATE TABLE syntax.

Only Hue Superusers can access S3 buckets and import files to create tables. To create tables by importing files from S3, you must assign and authorize a specific bucket to be used as an external S3 bucket for your environment. The bucket then appears like a home directory on the Hue web interface.

The maximum file size supported is three gigabytes.

Create roles and synchronize users to FreeIPA.
Make sure that the users who want to create tables by importing CSV files have EnvironmentAdmin or EnvironmentUser roles, and that you have synchronized users to FreeIPA. This is required for users accessing the data lake. Ranger will allow these users to access external buckets, without which the authorization will fail.
To assign roles to users, see Assigning resources to users in the Management Console documentation.
To synchronize users to FreeIPA, see Performing user sync in the Management Console documentation.
Add an external S3 bucket to your CDW environment.
If you try to access an external S3 bucket from the Hue web interface without adding it to the CDW environment, then Impala or Hive may display the “AccessDeniedException 403” exception. Make sure that your Cloudera Data Warehouse (CDW) environment has access to the S3 buckets that you want to access from Hue.
When you create a Virtual Warehouse in the CDW service, a cluster is created in your AWS account. This cluster has two buckets. One bucket is used for managed data and the other is used for external data. Access to these two buckets is controlled by AWS instance profiles.
To add read/write access to external S3 buckets that reside in the same AWS account as the CDW service cluster or that are different from the account where the CDW service cluster resides, see the corresponding links at the bottom of the page.
To add an external S3 bucket to your CDW environment:
1. In the Data Warehouse service, expand the Environments column by clicking the More… menu on the left side of the page.
2. In the Environments column, click the search icon and locate the environment in which you want to add the S3 bucket.
3. Click the edit icon in the tile. This launches the Environment Details page.
4. In the Environment Details page, toward the bottom of the page, type the name of the AWS bucket you want to configure access to in the Add External S3 Bucket text box.
  If the bucket belongs to another AWS account, then select the Bucket belongs to different AWS account option.
5. Select the access mode.
  Read-only access is sufficient to import data in Hue.
6. Click Add Bucket to save the configuration. A success message displays at the top of the page.
7. Click Apply to update the CDW environment.
  note
  If you configure read only access to an external S3 bucket, there is no need to restart Virtual Warehouses. However, if you configure read/write access to an external S3 bucket, you must restart Virtual Warehouses by suspending them and starting them again.
Add users to the Hadoop SQL Ranger policies
You must grant the Hadoop SQL Ranger permissions to enable your users to access specific tables and secure your data from unauthorized access.
1. Sign in to Cloudera Data Warehouse.
2. Click the More… option on your Database Catalog and click Open Ranger.
3. On the Ranger Service Manager page, click Hadoop SQL.
4. Select the all - url policy.
  The Edit Policy page is displayed.
5. Under the Add Conditions section, add the users under the Select User column and add permissions such as Create, Alter, Drop, Select, and so on from the Permissions column.
6. Scroll to the bottom of the page and click Save.
Enable the S3 file browser in Hue.
To enable access to S3 buckets from the Hue web UI, you must add the AWS environment details in the hue-safety-valve configuration from your Virtual Warehouse. After enabling the S3 file browser, you can browse the S3 buckets, create folders, and upload files from your computer, and import files to create tables.
1. Sign in to Cloudera Data Warehouse.
2. Go to the Virtual Warehouse from which you want to access the S3 buckets and click its edit icon.
3. On the Virtual Warehouses detail page, click the Hue tab and select hue-safety-valve from the drop-down menu.
4. Add the following configuration for Hive or Impala Virtual Warehouse in the space provided:
  For Hive Virtual Warehouse:
```
[desktop]
# Remove the file browser from the blocked list of apps.
# Tweak the app_blacklist property to suit your app configuration.
app_blacklist=oozie,search,hbase,security,pig,sqoop,spark,impala

[aws]
[[aws_accounts]]
[[[default]]]
access_key_id=[***AWS-ACCESS-KEY***]
secret_access_key=[***SECRET-ACCESS-KEY***]
region=[***AWS-REGION***]

[filebrowser]
# (Optional) To set a specific home directory path:
remote_storage_home=s3a://[***S3-BUCKET-NAME***]
```
  For Impala Virtual Warehouse:
```
[desktop]
# Remove the file browser from the blocked list of apps.
# Tweak the app_blacklist property to suit your app configuration.
app_blacklist=spark,zookeeper,hive,hbase,search,oozie,jobsub,pig,sqoop,security

[aws]
[[aws_accounts]]
[[[default]]]
access_key_id=[***AWS-ACCESS-KEY***]
secret_access_key=[***SECRET-ACCESS-KEY***]
region=[***AWS-REGION***]

[filebrowser]
# (Optional) To set a specific home directory path:
remote_storage_home=s3a://[***S3-BUCKET-NAME***]
```
5. Click Apply in the upper right corner of the page.
  The S3 File Browser icon appears on the left Assist panel on the Hue web UI after the Virtual Warehouse restarts.

To import the CSV file and create the table:

In the CDW service Overview page, select the Virtual Warehouse in which you want to create the table, click the options menu in the upper right corner and click Open Hue.
From the left assist panel, click on Importer.
On the Importer screen, click .. at the end of the Path field:

Choose a file pop-up is displayed.
Type s3a:// in the address text box and press enter.
The S3 buckets associated with the CDW environment are displayed. You can narrow down the list of results using the search option.

If the file is present on your computer, then you can upload it to S3 by clicking Upload a file. To do this, you must have enabled read/write access to the S3 bucket from the CDW environment.
Select the CSV file that you want to import into Hue.
Hue displays the preview of the table along with the format:

Hue automatically detects the field separator, record separator, and the quote character from the CSV file. If you want to override a specific setting, then you can change it by selecting a different value from the dropdown menu.
Click Next.
On this page, you can set the table destination, partitions, and change the column data types.
Verify the settings and click Submit to create the table.
The CREATE TABLE query is triggered:

Hue displays the logs and opens the Table Browser from which you can view the newly created table when the operation completes successfully.