START_REFRESH

Refreshes projections in the current schema with the latest data of their respective anchor tables. START_REFRESH runs asynchronously in the background, and updates system table PROJECTION_REFRESHES. This function has no effect if a refresh is already running.

To refresh only projections of a specific table, use REFRESH. When you deploy a design through Database Designer, it automatically refreshes its projections.

Syntax

START_REFRESH()

Privileges

None

Requirements

All nodes must be up.

Refresh Methods

Vertica can refresh a projection from one of its buddies, if one is available. In this case, the target projection gets the source buddy's historical data. Otherwise, the projection is refreshed from scratch with data of the latest epoch at the time of the refresh operation. In this case, the projection cannot participate in historical queries on any epoch that precedes the refresh operation.

To determine the method used to refresh a given projection, query REFRESH_METHOD from system table PROJECTION_REFRESHES.

Example

=> SELECT START_REFRESH();
             START_REFRESH
----------------------------------------
 Starting refresh background process.
(1 row)

See Also