Analytical View States

The analytical views in Arcadia Data have four possible states: UNUSABLE, INVALID, STALE, and FRESH.

In addition to describing the Four States of Analytical Views, this topic explains how an analytical view may become stale, and what events trigger transitions between states.

Four States of Analytical Views
State Description
UNUSABLE

Analytical view is created, but has never been refreshed.
INVALID Base tables(s) were subject to DDL operation after most recent refresh. The analytical view is not consistent with base table definitions, and cannot be used.
STALE

Base table data was changed after most recent refresh. The analytical view may be used, but the query results may be incomplete/inaccurate.
FRESH

The data in the analytical view is current, or up-to-date with the base table(s). The analytical view may be used to safely route the query, and will return accurate results.

Staleness Period

In Arcadia Data, it is possible to control the staleness of analytical views at the session level.

The STALENESS_PERIOD query option specifies, in minutes, how stale an analytical view can become before ArcEngine stops routing queries to it.

The default value of STALENESS_PERIOD is 1440 minutes, or 24 hours.

ArcEngine checks the difference between current time and the last successful refresh of the analytical view to determine its age. If the age exceeds the STALENESS_PERIOD value, ArcEngine marks the analytical view as stale.

Effect of Changes to Tables

Various database events can change the state of an analytical view. Some operations have no effect, while others trigger a state change to INVALID.

Database operations that do not have an effect on the state of analytical views include the following:

  • Adding or dropping a partition in the base table does not effect the analytical views based on that table, and does not cause analytical views to become INVALID.
  • Changes in location, server properties, or table properties do not effect analytical views and do not cause them to become INVALID.
  • ADD operations on columns to the base table does not cause analytical views to become INVALID.

Database changes that trigger an INVALID state in analytical views include the following:

  • Change to the name of the base table.
  • Change to the base table column name.
  • Change to the base table column type.
  • DROP or REPLACE operation on the columns of the base table that are used in the analytical view.