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 Database 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 Database 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 Database 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 Database 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