Synchronizing Metadata

If you revive a database, it will use the synced catalog maintained in communal storage. The catalog contains your database's metadata.

When an Eon Mode database is running, Vertica automatically syncs the catalog every five minutes by default. Thus, it is not usually necessary to intervene in the synchronization process. However, before shutting down it is a good idea to make sure that the persistent copy of the catalog contains all recent changes. You can use the following processes to make sure the database's catalog is up to date when you revive.

Check When the Catalog Was Last Synchronized

While the database is running:

The following system tables are only available when the database is up.

Use system table CATALOG_SYNC_STATE to see how recently each node synced its catalog to communal storage. Checking this requires the database to still be running.

=> SELECT * FROM catalog_sync_state;

The system table CATALOG_TRUNCATION_STATUS also indicates how up to date the catalog is on communal storage. It is completely up to date when the current catalog version is the same as the catalog truncation version. Checking this requires the database to still be running.

=> SELECT * FROM catalog_truncation_status;

When the database is not running:

If your database is not currently running, a JSON file containing additional cluster information is located in communal storage. This file indicates the catalog truncation version and timestamp of the last sync to communal storage:

/metadata/database‑name/cluster_config.json

Manually Sync the Catalog

The sync_catalog function immediately synchronizes the catalog on all nodes or a specific node. 

=> SELECT sync_catalog();

Customize Catalog Sync Interval

Use the CatalogSyncInterval parameter to set a time interval for which the metadata is pushed to communal storage:

=> ALTER DATABASE DEFAULT SET CatalogSyncInterval = 10 minutes