Display query and analysis results on multiple pages

Paging methods

Display the query result by page

The value of the offset parameter increases for reading logs by page. When the value reaches a certain number, zero lines are returned and the progress becomes complete. In this case, all data has been read.

Sample code of querying logs by page

• Pseudocode

  offset = 0// Indicates that logs are read beginning from line 0.
  lines = 100// Indicates that 100 lines are read at a time.
  query = "status:200"// Indicates that only logs where the value of the status field contains 200 are queried.
  while True:
       response = get_logstore_logs(query, offset, lines) // The response to the read request.
       process (response)                                 // Use the custom logic to process the query result.
       If response.get_count() == 0 && response.is_complete()   
           Stop reading logs and exit the current loop.
       else
          offset += 100                        // The value of the offset parameter increases by 100. The next 100 lines are to be read.

• Python code
  For more information about the sample code, see Log Service Python SDK.

      endpoint = ''# The endpoint that matches the region of the project created in the preceding step.
      accessKeyId = ''# Your Alibaba Cloud AccessKey ID.
      accessKey = ''# Your Alibaba Cloud AccessKey secret.
      project = ''# The name of the project created in the preceding step.
      logstore = ''# The name of the Logstore created in the preceding step.
      client = LogClient(endpoint, accessKeyId, accessKey)
      topic = ""
      query = "index"
      From = int(time.time()) - 600
      To = int(time.time())
      log_line = 100
      offset = 0
      while True:
          res4 = Nonefor retry_time in range(0, 3):
              req4 = GetLogsRequest(project, logstore, From, To, topic, query, log_line, offset, False)
              res4 = client.get_logs(req4)
              if res4 isnotNoneand res4.is_completed():
                  break
              time.sleep(1)
          offset += 100if res4.is_completed() && res4.get_count() == 0:
                break;
          if res4 isnotNone:
              res4.log_print()  # Display the execution result.

• Java code

  For more information about the sample code, visit Procedure.

          int log_offset = 0;
          int log_line = 100;// Indicates that 100 lines are read at a time. The maximum value of this parameter is 100. If you need to read more than 100 lines at a time, use the offset parameter. Note that the offset and lines parameters are available to keyword-based queries instead of SQL-based queries. To read more than 100 lines at a time during a SQL-based query, use the LIMIT statement.
          while (true) {
              GetLogsResponse res4 = null;
              // For each log offset, 100 lines are read at a time. If a read operation fails, a maximum of 3 retry attempts are allowed.
              for (int retry_time = 0; retry_time < 3; retry_time++) {
                  GetLogsRequest req4 = new GetLogsRequest(project, logstore, from, to, topic, query, log_offset,
                          log_line, false);
                  res4 = client.GetLogs(req4);
  
                  if (res4 ! = null && res4.IsCompleted()) {
                      break;
                  }
                  Thread.sleep(200);
              }
              System.out.println("Read log count:" + String.valueOf(res4.GetCount()));
              log_offset += log_line;
              if (res4.IsCompleted() && res4.GetCount() == 0) {
                          break;
              }
  
          }
                      

Display the analysis result by page

The offset and lines parameters of the GetLogStoreLogs operation are not available to SQL-based analysis. If you traverse the offset parameter based on the preceding method to display the analysis result by page, the SQL-based analysis result will be the same for each execution. If you try to obtain all computing results at the same time, the following issues may occur because of the oversized data in the result:

• The latency of transmitting oversized data is high.
• The memory usage is high. Storing large-sized data in the analysis result occupies the storage space of the client memory.

limit Offset, Line

• Offset: the line from which the result is to be read.
• Line: the number of lines to be read. The value of Line does not have an upper limit. However, reading too many lines at a time may result in a high network latency and an adverse impact on the processing speed of the client.

Assume that 2,000 lines are returned for the analysis statement * | selectcount(1) , url group by url. You can specify that all data is to be read at four intervals, with 500 lines being read at a time.

* | selectcount(1) , url  group by url  limit 0, 500
* | selectcount(1) , url  group by url  limit 500, 500
* | selectcount(1) , url  group by url  limit 1000, 500
* | selectcount(1) , url  group by url  limit 1500, 500

Sample code of displaying the SQL-based analysis result by page

• Pseudocode

      offset = 0// Indicates that logs are read from the zeroth line.
      lines = 500// Indicates that 500 lines are read at a time.
      query = "* | select count(1) , url  group by url  limit "whileTrue:
      real_query = query + offset + "," +  lines
      response = get_logstore_logs(real_query) // The response to the read request.
      process (response)                       // Use the custom logic to process the analysis result.
      If response.get_count() == 0   
           Stop reading logs and exit the current loop.
      else
          offset += 500                        // The value of the offset parameter increases by 500. The next 500 lines are to be read.

• Python code

      endpoint = ''# The endpoint that matches the region of the project created in the preceding step.
      accessKeyId = ''# Your Alibaba Cloud AccessKey ID.
      accessKey = ''# Your Alibaba Cloud AccessKey secret.
      project = ''# The name of the project created in the preceding step.
      logstore = ''# The name of the Logstore created in the preceding step.
      client = LogClient(endpoint, accessKeyId, accessKey)
      topic = ""
      origin_query = "* | select count(1) , url  group by url  limit "
      From = int(time.time()) - 600
      To = int(time.time())
      log_line = 100
      offset = 0
      while True:
          res4 = None
          query = origin_query + str(offset) + " , " + str(log_line)
          for retry_time in range(0, 3):
              req4 = GetLogsRequest(project, logstore, From, To, topic, query)
              res4 = client.get_logs(req4)
              if res4 isnotNoneand res4.is_completed():
                  break
              time.sleep(1)
          offset += 100if res4.is_completed() && res4.get_count() == 0:
                break;
          if res4 isnotNone:
              res4.log_print()  # Display the execution result.

• Java code:

          int log_offset = 0;
          int log_line = 500;
          String origin_query = "* | select count(1) , url  group by url  limit "while (true) {
              GetLogsResponse res4 = null;
              // For each log offset, 500 lines are read at a time. If a read operation fails, a maximum of 3 retry attempts are allowed.
              query = origin_query + log_offset + "," + log_line;
              for (int retry_time = 0; retry_time < 3; retry_time++) {
                  GetLogsRequest req4 = new GetLogsRequest(project, logstore, from, to, topic, query);
                  res4 = client.GetLogs(req4);
  
                  if (res4 ! = null && res4.IsCompleted()) {
                      break;
                  }
                  Thread.sleep(200);
              }
              System.out.println("Read log count:" + String.valueOf(res4.GetCount()));
              log_offset += log_line;
              if (res4.GetCount() == 0) {
                          break;
              }
  
          }