analyzing-schema-change-storage-risk

Estimate CockroachDB schema change storage by analyzing per-index range sizes using SHOW RANGES WITH DETAILS, then applying a 3× free-space rule to prevent mid-backfill disk exhaustion during operations.

A CockroachDB backfill causes disk exhaustion when adding columns because the operation temporarily requires multiple times the largest range size in additional storage, necessitating a conservative 4× to 5× safety buffer.

Checking storage capacity for a CockroachDB schema change requires admin or ZONECONFIG privileges to execute the necessary safety checks and analyze range details using the LIMIT clause.

A CREATE INDEX backfill on large CockroachDB tables requires applying a 3× free-space rule based on per-index range sizes, escalating to a 4× safety buffer for production environments to avoid disk exhaustion.

Plan capacity for an ALTER PRIMARY KEY operation by analyzing per-index range sizes and enforcing a 5× safety margin, ensuring sufficient disk space to complete the backfill without exhausting storage.

Estimating schema change storage using range sizes requires applying LIMIT usage to SHOW RANGES WITH DETAILS queries on large tables, with limitations including the need for conservative 4× safety buffers to handle unpredictable production data distribution.