diff --git a/db/knex_migrations/2025-12-22-0121-optimize-important-indexes.js b/db/knex_migrations/2025-12-22-0121-optimize-important-indexes.js
new file mode 100644
index 000000000..4208f9511
--- /dev/null
+++ b/db/knex_migrations/2025-12-22-0121-optimize-important-indexes.js
@@ -0,0 +1,37 @@
+exports.up = async function (knex) {
+    const isSQLite = knex.client.dialect === "sqlite3";
+
+    if (isSQLite) {
+        // For SQLite: Use partial indexes with WHERE important = 1
+        // Drop existing indexes using IF EXISTS
+        await knex.raw("DROP INDEX IF EXISTS monitor_important_time_index");
+        await knex.raw("DROP INDEX IF EXISTS heartbeat_important_index");
+
+        // Create partial indexes with predicate
+        await knex.schema.alterTable("heartbeat", function (table) {
+            table.index([ "monitor_id", "time" ], "monitor_important_time_index", {
+                predicate: knex.whereRaw("important = 1")
+            });
+            table.index([ "important" ], "heartbeat_important_index", {
+                predicate: knex.whereRaw("important = 1")
+            });
+        });
+    }
+    // For MariaDB/MySQL: No changes (partial indexes not supported)
+};
+
+exports.down = async function (knex) {
+    const isSQLite = knex.client.dialect === "sqlite3";
+
+    if (isSQLite) {
+        // Restore original indexes
+        await knex.raw("DROP INDEX IF EXISTS monitor_important_time_index");
+        await knex.raw("DROP INDEX IF EXISTS heartbeat_important_index");
+
+        await knex.schema.alterTable("heartbeat", function (table) {
+            table.index([ "monitor_id", "important", "time" ], "monitor_important_time_index");
+            table.index([ "important" ]);
+        });
+    }
+    // For MariaDB/MySQL: No changes
+};
diff --git a/test/backend-test/test-migration.js b/test/backend-test/test-migration.js
new file mode 100644
index 000000000..87e5ff9df
--- /dev/null
+++ b/test/backend-test/test-migration.js
@@ -0,0 +1,133 @@
+const { describe, test } = require("node:test");
+const fs = require("fs");
+const path = require("path");
+const { GenericContainer, Wait } = require("testcontainers");
+
+describe("Database Migration - Optimize Important Indexes", () => {
+    test("SQLite: All migrations run successfully", async () => {
+        const testDbPath = path.join(__dirname, "../../data/test-migration.db");
+        const testDbDir = path.dirname(testDbPath);
+
+        // Ensure data directory exists
+        if (!fs.existsSync(testDbDir)) {
+            fs.mkdirSync(testDbDir, { recursive: true });
+        }
+
+        // Clean up any existing test database
+        if (fs.existsSync(testDbPath)) {
+            fs.unlinkSync(testDbPath);
+        }
+
+        // Use the same SQLite driver as the project
+        const Dialect = require("knex/lib/dialects/sqlite3/index.js");
+        Dialect.prototype._driver = () => require("@louislam/sqlite3");
+
+        const knex = require("knex");
+        const db = knex({
+            client: Dialect,
+            connection: {
+                filename: testDbPath
+            },
+            useNullAsDefault: true,
+        });
+
+        // Setup R (redbean) with knex instance like production code does
+        const { R } = require("redbean-node");
+        R.setup(db);
+
+        try {
+            // Use production code to initialize SQLite tables (like first run)
+            const { createTables } = require("../../db/knex_init_db.js");
+            await createTables();
+
+            // Run all migrations like production code does
+            await R.knex.migrate.latest({
+                directory: path.join(__dirname, "../../db/knex_migrations")
+            });
+
+            // Test passes if migrations complete successfully without errors
+
+        } finally {
+            // Clean up
+            await R.knex.destroy();
+            if (fs.existsSync(testDbPath)) {
+                fs.unlinkSync(testDbPath);
+            }
+        }
+    });
+
+    test(
+        "MariaDB: All migrations run successfully",
+        {
+            skip:
+                !!process.env.CI &&
+                (process.platform !== "linux" || process.arch !== "x64"),
+        },
+        async () => {
+            // Start MariaDB container (using MariaDB 12 to match current production)
+            const mariadbContainer = await new GenericContainer("mariadb:12")
+                .withEnvironment({
+                    "MYSQL_ROOT_PASSWORD": "root",
+                    "MYSQL_DATABASE": "kuma_test",
+                    "MYSQL_USER": "kuma",
+                    "MYSQL_PASSWORD": "kuma"
+                })
+                .withExposedPorts(3306)
+                .withWaitStrategy(Wait.forLogMessage("ready for connections", 2))
+                .withStartupTimeout(120000)
+                .start();
+
+            // Wait a bit more to ensure MariaDB is fully ready
+            await new Promise(resolve => setTimeout(resolve, 2000));
+
+            const knex = require("knex");
+            const knexInstance = knex({
+                client: "mysql2",
+                connection: {
+                    host: mariadbContainer.getHost(),
+                    port: mariadbContainer.getMappedPort(3306),
+                    user: "kuma",
+                    password: "kuma",
+                    database: "kuma_test",
+                    connectTimeout: 60000,
+                },
+                pool: {
+                    min: 0,
+                    max: 10,
+                    acquireTimeoutMillis: 60000,
+                    idleTimeoutMillis: 60000,
+                },
+            });
+
+            // Setup R (redbean) with knex instance like production code does
+            const { R } = require("redbean-node");
+            R.setup(knexInstance);
+
+            try {
+                // Use production code to initialize MariaDB tables
+                const { createTables } = require("../../db/knex_init_db.js");
+                await createTables();
+
+                // Run all migrations like production code does
+                await R.knex.migrate.latest({
+                    directory: path.join(__dirname, "../../db/knex_migrations")
+                });
+
+                // Test passes if migrations complete successfully without errors
+
+            } finally {
+                // Clean up
+                try {
+                    await R.knex.destroy();
+                } catch (e) {
+                    // Ignore cleanup errors
+                }
+                try {
+                    await mariadbContainer.stop();
+                } catch (e) {
+                    // Ignore cleanup errors
+                }
+            }
+        }
+    );
+});