创建和管理 Stream

This tutorial guides you on how to create and manage streams in HStream Platform.

Preparation

1. If you do not have an account, please apply for a trial first and log in. After logging in, click Streams on the left sidebar to enter the streams page.

2. If you have already logged in, click Streams on the left sidebar to enter the Streams page.

3. Click the New stream button to create a stream.

Create a stream

After clicking the New stream button, you will be directed to the New Stream page. You need to set some necessary properties for your stream and create it:

1. Specify the stream name. You can refer to Guidelines to name a resource to name a stream.

2. Fill in with the number of shards you want this stream to have. The default value is 1.

   Shard is the primary storage unit for the stream. For more details, please refer to Sharding in HStreamDB.

3. Fill in with the number of replicas for each stream. The default value is 3.

4. Fill in with the number of retention for each stream. Default value is 72. Unit is hour.

5. Click the Confirm button to create a stream.

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For more details about replicas and retention, please refer to Attributes of a Stream.

WARNING

Currently, the number of replicas and retention are fixed for each stream in HStream Platform. We will gradually adjust these attributes in the future.

View streams

The Streams page lists all the streams in your account with a high-level overview. For each stream, you can view the following information:

• The name of the stream.

• The Creation time of the stream.

• The number of shards in a stream.

• The number of replicas in a stream.

• The Data retention period of the records in a stream.

• Actions, which for the extra operations of the stream:

  • Metrics: View the metrics of the stream.
  • Subscriptions: View the subscriptions of the stream.
  • Shards: View the shard details of the stream.
  • Delete: Delete the stream.

To view a specific stream, click the name. The details page of the stream will be displayed.

View stream details

The details page displays the detailed information of a stream:

1. All the information in the streams page.

2. Different tabs are provided to display the related information of the stream:

   • Metrics: View the metrics of the stream.
   • Subscriptions: View the subscriptions of the stream.
   • Shards: View the shard details of the stream.
   • Records: Search records in the stream.

View stream metrics

After clicking the Metrics tab, you can view the metrics of the stream. The default duration is last 5 minutes. You can select different durations to control the time range of the metrics:

• last 5 minutes
• last 1 hour
• last 3 hours
• last 6 hours
• last 12 hours
• last 1 day
• last 3 days
• last 1 week

The metrics of the stream include (with last 5 minutes as an example), from left to right:

• The Append records throughout chart shows the number of records to the stream per second in the last 5 minutes.
• The Append bytes throughout chart shows the number of bytes to the stream per second in the last 5 minutes.
• The Total requests chart shows the number of requests to the stream in the last 5 minutes. Including failed requests.
• The Append requests throughout chart shows the number of requests to the stream per second in the last 5 minutes.

View stream subscriptions

After clicking the Subscriptions tab, you can view the subscriptions of the stream.

To create a new subscription, please refer to Create a Subscription.

For more details about the subscription, please refer to Subscription Details

View stream shards

After clicking the Shards tab, you can view the shard details of the stream.

For each shard, you can view the following information:

• The ID of the shard.
• The Range start of the shard.
• The Range end of the shard.
• The current Status of the shard.

You can use the ID to get records. Please refer to Get records in a stream or Get Records.

Get records in a stream

After clicking the Records tab, you can get records in the stream.

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To get records from any streams, please refer to Get Records.

You can specify the following filters to get records:

• Shard: Select one of the shards in the stream you want to get records from.
• Special filters:
  • Start record ID: Get records after a specified record ID. The default is the first record.
  • Start date: Get records after a specified date.

After providing the filters (or not), click the Get records button to get records. Each record is displayed in a row with the following information:

• The ID of the record.
• The Key of the record.
• The Value of the record.
• The Shard ID of the record.
• The Creation time of the record.

Delete a Stream

This section describes how to delete a stream.

WARNING

If a stream has subscriptions, this stream cannot be deleted.

DANGER

Deleting a stream is irreversible, and the data cannot be recovered after deletion.

Delete a stream on the Streams page

1. Navigate to the Streams page.
2. Click the Delete icon of the stream you want to delete. A confirmation dialog will pop up.
3. Confirm the deletion by clicking the Confirm button in the dialog.

Delete a stream on the Stream Details page

1. Navigate to the details page of the stream you want to delete.
2. Click the Delete button. A confirmation dialog will pop up.
3. Confirm the deletion by clicking the Confirm button in the dialog.