Add basic schema

chromadb/migrations/sysdb/00004-tenants-databases.sqlite.sql

@@ -0,0 +1,19 @@
+CREATE TABLE tenants (
+    id TEXT PRIMARY KEY,
+    name TEXT NOT NULL,
+    UNIQUE (name)
+);
+
+CREATE TABLE databases (
+    id TEXT PRIMARY KEY,
+    name TEXT NOT NULL,
+    tenant_id TEXT NOT NULL REFERENCES tenants(id) ON DELETE CASCADE,
+    UNIQUE (name)
+);
+
+ALTER TABLE collections
+    ADD COLUMN database_id TEXT NOT NULL REFERENCES databases(id); -- ON DELETE CASCADE not supported by sqlite in ALTER TABLE
+
+-- Create default tenant and database
+INSERT INTO tenants (id, name) VALUES ('default', 'default');
+INSERT INTO databases (id, name, tenant_id) VALUES ('default', 'default', 'default');