Prepare to migrate to the new versioning system

scripts/database/create_names_table.sql

@@ -4,10 +4,26 @@
 
 CREATE TABLE names (
     name VARCHAR(128) NOT NULL PRIMARY KEY,
-    pointer UUID NOT NULL REFERENCES packages(pointer),
+    pointer UUID NULL,
     -- constraints
-    CONSTRAINT lowercase_names CHECK (name = LOWER(name))
+    CONSTRAINT lowercase_names CHECK (name = LOWER(name)),
+    CONSTRAINT package_names_fkey FOREIGN KEY (pointer) REFERENCES packages(pointer) ON DELETE SET NULL
 );
 
 -- Lowercase constraint added upon the following issue:
 -- https://github.com/confused-Techie/atom-backend/issues/90
+
+/*
+-- `pointer` was NOT NULL, then we made it nullable.
+-- The previous foreign key has been dropped and a new `package_names_fkey`
+-- has need added to avoid supply chain attacks.
+-- `pointer` is set to NULL when a row in packages table is deleted.
+-- Steps made to apply this change:
+
+ALTER TABLE names ALTER COLUMN pointer DROP NOT NULL;
+
+ALTER TABLE names DROP CONSTRAINT previous_foreign_key_name;
+
+ALTER TABLE names
+ADD CONSTRAINT package_names_fkey FOREIGN KEY (pointer) REFERENCES packages(pointer) ON DELETE SET NULL;
+*/

scripts/database/create_versions_table.sql

@@ -11,6 +11,8 @@ CREATE TABLE versions (
     semver VARCHAR(256) NOT NULL,
     license VARCHAR(128) NOT NULL,
     engine JSONB NOT NULL,
+    created TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP,
     meta JSONB,
     -- generated columns
     semver_v1 INTEGER GENERATED ALWAYS AS
@@ -21,5 +23,15 @@ CREATE TABLE versions (
         (CAST ((regexp_match(semver, '^(\d+)\.(\d+)\.(\d+)'))[3] AS INTEGER)) STORED,
     -- constraints
     CONSTRAINT semver2_format CHECK (semver ~ '^\d+\.\d+\.\d+'),
-    CONSTRAINT unique_pack_version UNIQUE(package, semver_v1, semver_v2, semver_v3)
+    CONSTRAINT unique_pack_version UNIQUE(package, semver)
 );
+
+-- Create a function and a trigger to set the current timestamp
+-- in the `updated` column of the updated row.
+-- The function now_on_updated_package() is the same defined in
+-- the script for the `packages` table.
+
+CREATE TRIGGER trigger_now_on_updated_versions
+    BEFORE UPDATE ON versions
+    FOR EACH ROW
+EXECUTE PROCEDURE now_on_updated_package();