17.10 - FastExport Sessions State Displays - Advanced SQL Engine - Teradata Database

Teradata Vantageā„¢ - Database Utilities

Product
Advanced SQL Engine
Teradata Database
Release Number
17.10
Release Date
July 2021
Content Type
Configuration
Publication ID
B035-1102-171K
Language
English (United States)

FastExport of data includes sessions under which Teradata SQL statements are executed, as well as sessions used to transfer response data to the host.

The Teradata SQL session assumes one of five sequential states:
  • Executing the select
  • Releasing resource locks
  • Vertical data redistribution
  • Horizontal data redistribution
  • Inactive

Vertical data redistribution and horizontal data redistribution are processes executed to prepare the response data from a SELECT request for transfer back to the host. Vertical redistribution occurs only if the SELECT contains an ORDER BY clause. The idle state occurs before the select request is transmitted to the Teradata system, or while the FastExport sessions are transmitting data to the host.

FastExport sessions are children of the Teradata SQL session that executes the select request. A child session exists in one of two states. A child session in the inactive state means that either the select has not completed, or that the host utility has not yet issued a request for this child session in returning response data. A child session in the active state is currently transmitting response data.

Like FastLoad and MultiLoad, the FastExport utility executes bulk activities. The Teradata system limits the maximum number of load operations (that is, FastExport, FastLoad, or MultiLoad) to the number specified in DBS Control field MaxLoadTasks.

Examples of Teradata SQL sessions involved in FastExport activity and examples of the output for a FastExport session are shown in the following sections.

Teradata SQL Session - Releasing Locks

The following shows an example display of a single FastExport Teradata SQL session in release locks state.

Session State Query Results : 00/06/14 18:35:54
               
Host Session PE  DBC User ID
---- ------- --- -----------
 114 1090    1-4 DBC
               
State Details : Active PARENT session involved in FastExport
               
FastExport Phase : Vertical redistribution.
               
Statements Dispatched Time     CPU Usage Accesses
---------- ---------- -------- --------- -------- 
         1          1 18:35:54      6174    2,922
               
Detail information for CHILDREN sessions in FastExport Util.
               
Session # Request # State    
--------- --------- -------- 
     1091         0 Inactive
     1092         0 Inactive
     1093         0 Inactive
     1094         0 Inactive

Teradata SQL Session - Vertical Redistribution

The following shows an example display of the Teradata SQL session in the vertical redistribution state. The select request consists of a single SELECT statement.

Session State Query Results : 00/06/13 18:38:59
               
Host Session PE  DBC User ID
---- ------- --- -----------
 114 1090    1-4 DBC
               
State Details : Active PARENT session involved in FastExport
               
FastExport Phase : Vertical redistribution.
               
Statements Dispatched Time     CPU Usage Accesses
---------- ---------- -------- --------- -------- 
         1          1 18:37:54      6603    3,314
               
Detail information for CHILDREN sessions in FastExport Util.
               
Session # Request # State    
--------- --------- -------- 
     1091         0 Inactive 
     1092         0 Inactive   
     1093         0 Inactive 
     1094         0 Inactive   

The following example shows that the Teradata system continues to process the vertical redistribution phase.

Session State Query Results : 00/06/12 18:38:59
               
Host Session PE  DBC User ID
---- ------- --- -----------
 114 1090    1-4 DBC
               
State Details : Active PARENT session involved in FastExport
               
FastExport Phase : Horizontal redistribution.
               
Statements Dispatched Time     CPU Usage Accesses
---------- ---------- -------- --------- -------- 
         1          1 18:42:35      6603    3,314
               
Detail information for CHILDREN sessions in FastExport Util.
               
Session # Request # State    
--------- --------- -------- 
     1091         0 Inactive 
     1092         0 Inactive   
     1093         0 Inactive 
     1094         0 Inactive   

The CPU Usage and the Accesses counts have increased, indicating the Teradata system is in operation.

Teradata SQL Session - Horizontal Redistribution

With the Teradata SQL session in the horizontal redistribution state, the display might take the form shown in the following example.

Session State Query Results : 00/06/09 18:43:41
               
Host Session PE  DBC User ID
---- ------- --- -----------
 114 1090    1-4 DBC
               
State Details : Active PARENT session involved in FastExport
               
FastExport Phase : Horizontal redistribution.
               
Statements Dispatched Time     CPU Usage Accesses
---------- ---------- -------- --------- -------- 
         1          1 18:42:35      7893    5,305
               
Detail information for CHILDREN sessions in FastExport Util.
               
Session # Request # State    
--------- --------- -------- 
     1091         0 Inactive 
     1092         0 Inactive 
     1093         0 Inactive 
     1094         0 Inactive

FastExport Session - Inactive

The following example shows that the FastExport session is inactive, waiting for the select to complete.

Session State Query Results : 00/06/08 18:39:28
               
Host Session PE  DBC User ID
---- ------- --- -----------
 114 1091    N/A DBC
               
State Details : Child Session involved in FastExport Utility
               
FastExport Phase : Returning data.
               
Request # State    Parent Session
--------- -------- --------------
        0 Inactive           1069 

FastExport Session - Data Transmission

The following example shows FastExport returning data. This child session has returned one data block to the host for the first SELECT statement, where the response data contains 69 blocks.

Session State Query Results : 00/06/07 18:49:09
               
Host Session PE  DBC User ID
---- ------- --- -----------
 114 1091    N/A DBC
               
State Details : Child Session involved in FastExport Utility
               
FastExport Phase : Returning data.
               
Request # State    Statement Blocks Returned Total Block
--------- -------- --------- --------------- -----------
     1000 Active           1               4          69 
                   

FastExport transmission continues. As shown in the following example, the session has returned four data blocks to the host. In this way, the user is able to monitor the progress of the data transmission phase.

Session State Query Results : 00/06/06 18:50:52
               
Host Session PE  DBC User ID
---- ------- --- -----------
 114 1091    1-5 DBC
               
State Details : Child Session involved in FastExport Utility
               
FastExport Phase : Returning data.
Request # State    Statement Blocks Returned Total Block
--------- -------- --------- --------------- -----------
     1000 Active           1               4          69