Simple Log Service:GetHistograms

Usage notes

• Host consists of a project name and a Log Service endpoint. You must specify a project in Host.

• An AccessKey pair is created and obtained. For more information, see AccessKey pair.

  The AccessKey pair of an Alibaba Cloud account has permissions on all API operations. Using these credentials to perform operations in Log Service is a high-risk operation. We recommend that you use a RAM user to call API operations or perform routine O&M. To create a RAM user, log on to the RAM console. Make sure that the RAM user has the management permissions on Log Service resources. For more information, see Create a RAM user and authorize the RAM user to access Log Service.

• The information that is required to query logs is obtained. The information includes the name of the project to which the logs belong, the region of the project, and the name of the Logstore to which the logs belong. For more information, see Manage a project and Manage a Logstore.
• Indexes are configured before you query logs. For more information, see Create indexes.
• You can use the query parameter to specify only a search statement. You cannot use the parameter to specify an analytic statement. For more information about the syntax and limits of search statements, see Log search overview.
• The time range is evenly divided into subintervals in the responses. If the time range that is specified in the request remains unchanged, the subintervals in the responses also remain unchanged.
• If the number of logs in a Logstore significantly changes, Log Service cannot predict the number of times that you must call this operation to obtain the complete result. In this case, you must check the value of the progress parameter in the response of each request and determine whether to call this operation one more time to obtain the complete result. Each time you call this operation, the same number of charge units (CUs) are consumed.
• After a log is written to a Logstore, you can call the GetHistograms or GetLogs operation to query the log after a short latency. The latency of a query varies based on the type of the log. Log Service classifies logs into the following types based on the log time:
  • Real-time data: The difference between the time record in a log and the current time on Log Service is within the interval (-180 seconds,900 seconds]. For example, if a log was generated at 12:03:00, September 25, 2014 (UTC) and Log Service received the log at 12:05:00, September 25, 2014 (UTC), Log Service processes the log as real-time data. After real-time data is written to a Logstore, the data can be queried with a maximum latency of 3 seconds.

  • Historical data: The difference between the time record in a log and the current time on Log Service is within the interval [-604,800 seconds,-180 seconds). For example, if a log was generated at 12:00:00, September 25, 2014 (UTC) and Log Service received the log at 12:05:00, September 25, 2014 (UTC), Log Service processes the log as historical data. This type of log is usually generated in data backfill scenarios.

    After real-time data is written to a Logstore, the data can be queried with a maximum latency of 3 seconds. For 99.9% of queries, the latency is no more than 1 second.

• Log Service provides examples on how to call the GetHistograms operation by using Log Service SDK for Java. For more information, see Use GetHistograms to query the distribution of logs.

Authentication resources

The following table describes the authorization information that is required for this operation. You can add the information to the Action element of a RAM policy statement to grant a RAM user or a RAM role the permissions to call this operation.

Request headers

This operation uses only common request headers. For more information, see Common request headers.

Request syntax

GET /logstores/{logstore}/index?type=histogram HTTP/1.1

Request parameters

Response parameters

Examples

Sample requests

GET /logstores/test-logstore/index?type=histogram?from=1409529600&to=1409569200&topic=topic&query=with_pack_meta HTTP/1.1
Host:ali-test-project.cn-hangzhou.log.aliyuncs.com
Content-Type:application/json

Sample success responses

JSON format

HTTP/1.1 200 OK
Content-Type:application/json

{
  "from" : 1409529600,
  "to" : 1409569200,
  "count" : 2,
  "progress" : "Complete"
}

Error codes

For a list of error codes, see Service error codes.

For more information, see Common error codes.