Requirements for a K-Safe Physical Schema Design
Database Designer automatically generates designs with a K-safety of 1 for clusters that contain at least three nodes. (If your cluster has one or two nodes, it generates designs with a K-safety of 0. You can modify a design created for a three-node (or greater) cluster, and the K-safe requirements are already set.
If you create custom projections, your physical schema design must meet the following requirements to be able to successfully recover the database in the event of a failure:
- Segmented projections must be segmented across all nodes. Refer to Designing for Segmentation and Designing Segmented Projections for K-Safety.
- Replicated projections must be replicated on all nodes. See Designing Unsegmented Projections for K‑Safety.
- Segmented projections must have K+1 buddy projections—projections with identical columns and segmentation criteria, where corresponding segments are placed on different nodes.
You can use the
MARK_DESIGN_KSAFE function to find out whether your schema design meets requirements for K-safety.