-- +goose Up
-- The image library becomes a file library: any type is accepted and files are
-- served in slices (substring), so a download never loads the whole blob.
ALTER TABLE images RENAME TO files;
ALTER TABLE files RENAME CONSTRAINT images_pkey TO files_pkey;
ALTER INDEX images_created RENAME TO files_created;
-- Out of line and uncompressed, so substring() reads only the chunks it needs
-- (uploads are mostly jpeg/zip/pdf, which pglz would not shrink anyway).
ALTER TABLE files ALTER COLUMN data SET STORAGE EXTERNAL;
ALTER TABLE files
    ADD COLUMN kind text NOT NULL DEFAULT 'image'
        CHECK (kind IN ('image', 'document', 'audio', 'video', 'archive', 'other')),
    ALTER COLUMN size TYPE bigint;
ALTER TABLE files ALTER COLUMN kind DROP DEFAULT; -- everything so far was an image
CREATE INDEX files_kind_created ON files (kind, created_at DESC);
-- SET STORAGE only applies to values written from now on; re-store the existing
-- rows (`data = data` would keep the old TOAST pointer, the concatenation does not).
UPDATE files SET data = data || ''::bytea;

-- +goose Down
DROP INDEX files_kind_created;
ALTER TABLE files DROP COLUMN kind, ALTER COLUMN size TYPE integer, ALTER COLUMN data SET STORAGE EXTENDED;
ALTER INDEX files_created RENAME TO images_created;
ALTER TABLE files RENAME CONSTRAINT files_pkey TO images_pkey;
ALTER TABLE files RENAME TO images;