AMP Usage
Down AMPs
The impact of down AMPs on the Update operator depends on the following:
Table 40 describes the impact of down AMPs on Update operator tasks on fallback and nonfallback tables.
Condition 1 |
Condition 2 |
Result |
All of the target tables are fallback |
Not more than one AMP is down |
Update operator tasks continues to run as long as there is not more than one AMP down, either logically or physically, in a cluster. The down AMP does not participate in the application phase if: |
Two or more AMPs are down |
Update operator tasks do not run, or terminate if two or more AMPs are down, either logically or physically, in a cluster. Note: In the application phase, if AMPs are down to the extent that data on the DSU is corrupted, then you must restore the affected tables. |
|
One or more of the target tables is nonfallback |
One or more AMPs are down |
Update operator tasks terminate and you cannot restart until all of the AMPs are back up. Note: The Update operator also terminates if I/O errors corrupt the target tables in the application phase. |
Nonparticipant AMPs
An AMP can become nonparticipant for an Update operator task one of the following ways:
In effect, the Update operator treats a nonparticipant AMP as if it were a down AMP. Thus, the Update operator does not run if a cluster has any combination of more than one AMP that is:
And, if more than one AMP in a cluster becomes a nonparticipant during the application phase, the Update operator tasks cannot continue. The target tables are considered unusable, and must be recovered from archives.
One-AMP Systems
The Update operator cannot run on a one-AMP Teradata Database system, or on a multi-AMP system configured with one-AMP clusters. Any attempt to run Update in this environment triggers the Teradata Database to immediately reject the request, abort the job, and issue a diagnostic message stating that a one-AMP system is not supported.