GET_PROJECTION_STATUS

GET_PROJECTION_STATUS returns information relevant to the status of a projection:

• the current K-Safety status of the database

  K represents the maximum number of nodes in a database that can fail and recover with no loss of data. In Vertica V2.1, the value of K can be zero (0) or one (1). The value of K can be one (1) only when the Physical Schema design meets certain requirements. The designs generated by the Database Designer are K-Safe.

  A physical schema consists of a set of projections used to store data on disk. The projections in the physical schema are based on the objects in the Logical Schema.

• the number of nodes in the database
• whether or not the projection is segmented
• the number and names of buddy projections

  Buddy projections are required for K-Safety. Two projections are considered to be buddies if they contain the same columns and have the same range segmentation or hash segmentation using different node ordering. Buddy projections usually have different sort orders for query performance purposes.

• whether or not the projection is safe
• whether or not the projection is up-to-date

  A projection is up-to-date if it does not require a refresh in order to participate in query execution.

  This function may be deprecated and replaced by a mechanism similar to the SQL Virtual Tables (Monitoring API) in a future release.

Syntax

GET_PROJECTION_STATUS('projection');

Semantics

Notes

• You can use GET_PROJECTION_STATUS to monitor the progress of a projection data refresh (see ALTER PROJECTION).

  A refresh operation ensures that all projections on a node are up-to-date (can participate in query execution). This process may take a long time, depending on how much data is in the table(s).

Examples

=> SELECT GET_PROJECTION_STATUS('t1_sp2');

get_projection_status

-----------------------------------------------------------------------------------------------

Current system K is 0.

# of Nodes: 1.

t1_sp2 [Segmented: No] [# of Buddies: 0] [No buddy projections] [Safe: Yes] [UptoDate: No]