START_REFRESH

Refreshes projections in the current schema with the latest data of their respective.

Refreshes projections in the current schema with the latest data of their respective anchor tables. START_REFRESH runs asynchronously in the background, and updates the PROJECTION_REFRESHES system table. 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.

If a refresh would violate a table or schema disk quota, the operation fails. For more information, see Disk quotas.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Volatile

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 the REFRESH_METHOD column from the PROJECTION_REFRESHES system table.

Examples

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