Drops a row-level index from a Delta table. The child index Delta table is tombstoned at the current version.
DROP INDEX [IF EXISTS] <name> ON TABLE <table>## Overview DROP INDEX removes a row-level index from a Delta table. The index definition is removed from the parent's index registry and the child index Delta table is tombstoned in place rather than physically deleted, so time-travel reads at older parent versions continue to see the index. ## Behavior - The drop is recorded as a new commit on the parent table. The parent's version advances by one. - The child index Delta table at `<parent_path>/_delta_indexes/<index_id>` is not removed from storage. A subsequent VACUUM on the child path reclaims the space, but the standard parent-table VACUUM does not touch it. - IF EXISTS makes the drop idempotent. Without it, dropping a non-existent index raises an error. - Once dropped, query planning reverts to scanning the parent table for predicates the index used to serve. There is no automatic fallback to other indexes; the planner picks among the indexes that still exist. ## Access Control No specific privilege is required beyond table-level access in the standalone SQL layer. In a Control Plane deployment the table's MODIFY privilege governs index lifecycle. ## Compatibility DeltaForge extension. The Delta Lake protocol has no native row-index concept; DROP INDEX manages a sibling Delta table that DeltaForge writes alongside the parent.
| Name | Type | Description |
|---|---|---|
name | Specifies the index name to drop. Must match the name supplied at CREATE INDEX. | |
table | Specifies the parent Delta table that owns the index. | |
if_exists | Skip the operation silently when no index with that name exists on the table. |
-- Drop a known index
DROP INDEX idx_customer ON TABLE orders;-- Idempotent drop that succeeds when the index does not exist
DROP INDEX IF EXISTS idx_customer ON TABLE orders;