migrations: add latest_module_versions table

For golang/go#44710

Change-Id: Ifc590cdb4abd68a3d0210c8d5f9248154fbfd19a
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/297689
Trust: Jonathan Amsterdam <[email protected]>
Run-TryBot: Jonathan Amsterdam <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Jamal Carvalho <[email protected]>

Author: jba

migrations/000074_add_latest_module_versions.down.sql

@@ -0,0 +1,9 @@
+-- Copyright 2021 The Go Authors. All rights reserved.
+-- Use of this source code is governed by a BSD-style
+-- license that can be found in the LICENSE file.
+
+BEGIN;
+
+DROP TABLE latest_module_versions;
+
+END;

migrations/000074_add_latest_module_versions.up.sql

@@ -0,0 +1,32 @@
+-- Copyright 2021 The Go Authors. All rights reserved.
+-- Use of this source code is governed by a BSD-style
+-- license that can be found in the LICENSE file.
+
+BEGIN;
+
+CREATE TABLE latest_module_versions (
+    module_path_id INTEGER NOT NULL PRIMARY KEY,
+    raw_version TEXT NOT NULL,
+    cooked_version TEXT NOT NULL,
+    good_version TEXT NOT NULL,
+    raw_go_mod_bytes BYTEA NOT NULL,
+
+    FOREIGN KEY (module_path_id) REFERENCES paths(id) ON DELETE CASCADE
+);
+
+COMMENT ON TABLE latest_module_versions IS
+'TABLE latest_module_versions holds the latest versions of a module.';
+
+COMMENT ON COLUMN latest_module_versions.raw_version IS
+'COLUMN raw_version is the latest version of the module, ignoring retractions.';
+
+COMMENT ON COLUMN latest_module_versions.cooked_version IS
+'COLUMN cooked_version is the latest unretracted version of the module.';
+
+COMMENT ON COLUMN latest_module_versions.good_version IS
+'COLUMN good_version is the latest version of the module with a 2xx status.';
+
+COMMENT ON COLUMN latest_module_versions.raw_go_mod_bytes IS
+'COLUMN raw_go_mod_bytes is the contents of the go.mod file for the given module and raw version.';
+
+END;