crypto/sqlstore: add option to drop message index table for migration

Author: tulir

crypto/sql_store_upgrade/20-message-index-key.postgres.sql

@@ -0,0 +1,55 @@
+// Copyright (c) 2026 Tulir Asokan
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package sql_store_upgrade
+
+import (
+	"context"
+
+	"go.mau.fi/util/dbutil"
+)
+
+var DropCryptoMessageIndexForRewrite = false
+
+func init() {
+	const rewritePostgres = `
+		ALTER TABLE crypto_message_index DROP CONSTRAINT crypto_message_index_pkey;
+		ALTER TABLE crypto_message_index DROP COLUMN sender_key;
+		ALTER TABLE crypto_message_index ADD PRIMARY KEY (session_id, "index");
+	`
+	const createNewSQLite = `
+		CREATE TABLE new_crypto_message_index (
+			session_id CHAR(43),
+			"index"    INTEGER,
+			event_id   TEXT   NOT NULL,
+			timestamp  BIGINT NOT NULL,
+			PRIMARY KEY (session_id, "index")
+		);
+	`
+	const migrateSQLite = `
+		INSERT INTO new_crypto_message_index (session_id, "index", event_id, timestamp)
+		SELECT session_id, "index", event_id, timestamp FROM crypto_message_index;
+	`
+	const dropSQLite = `
+		DROP TABLE crypto_message_index;
+		ALTER TABLE new_crypto_message_index RENAME TO crypto_message_index;
+	`
+	Table.Register(-1, 20, 20, "Remove sender_key from crypto_message_index", dbutil.TxnModeOn, func(ctx context.Context, db *dbutil.Database) (err error) {
+		switch db.Dialect {
+		case dbutil.Postgres:
+			_, err = db.Exec(ctx, rewritePostgres)
+		case dbutil.SQLite:
+			if DropCryptoMessageIndexForRewrite {
+				_, err = db.Exec(ctx, createNewSQLite+dropSQLite)
+			} else {
+				_, err = db.Exec(ctx, createNewSQLite+migrateSQLite+dropSQLite)
+			}
+		default:
+			err = dbutil.ErrUnsupportedDialect
+		}
+		return
+	})
+}