arche / internal/store/migrate/sql/004_pack_delta.sql

commit 154431fd 
1-- Add delta-compression support to pack_index.
2-- delta_base_id: the blob ID this entry is encoded relative to (NULL = full object).
3-- delta_depth: length of the delta chain (0 = full object, 1 = one level of delta, …).
4ALTER TABLE pack_index ADD COLUMN delta_base_id BLOB;
5ALTER TABLE pack_index ADD COLUMN delta_depth INTEGER NOT NULL DEFAULT 0;