diff --git a/src/db.rs b/src/db.rs
index 36353da..8840b82 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -1288,545 +1288,3 @@ impl fmt::Debug for DB {
         write!(f, "RocksDB {{ path: {:?} }}", self.path())
     }
 }
-
-#[test]
-fn test_open_for_read_only() {
-    let path = "_rust_rocksdb_test_open_for_read_only";
-    {
-        let db = DB::open_default(path).unwrap();
-        db.put(b"k1", b"v1").unwrap();
-    }
-    {
-        let opts = Options::default();
-        let error_if_log_file_exist = false;
-        let db = DB::open_for_read_only(&opts, path, error_if_log_file_exist).unwrap();
-        assert_eq!(db.get(b"k1").unwrap().unwrap(), b"v1");
-        assert!(db.put(b"k2", b"v2").is_err());
-    }
-    let opts = Options::default();
-    assert!(DB::destroy(&opts, path).is_ok());
-}
-
-#[test]
-fn test_open_cf_for_read_only() {
-    let path = "_rust_rocksdb_test_open_cf_for_read_only";
-    let cfs = vec!["cf1"];
-    {
-        let mut opts = Options::default();
-        opts.create_if_missing(true);
-        opts.create_missing_column_families(true);
-        let db = DB::open_cf(&opts, path, cfs.clone()).unwrap();
-        let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
-    }
-    {
-        let opts = Options::default();
-        let error_if_log_file_exist = false;
-        let db = DB::open_cf_for_read_only(&opts, path, cfs, error_if_log_file_exist).unwrap();
-        let cf1 = db.cf_handle("cf1").unwrap();
-        assert_eq!(db.get_cf(cf1, b"k1").unwrap().unwrap(), b"v1");
-        assert!(db.put_cf(cf1, b"k2", b"v2").is_err());
-    }
-    let opts = Options::default();
-    assert!(DB::destroy(&opts, path).is_ok());
-}
-
-#[test]
-fn external() {
-    let path = "_rust_rocksdb_externaltest";
-    {
-        let db = DB::open_default(path).unwrap();
-        let p = db.put(b"k1", b"v1111");
-        assert!(p.is_ok());
-        let r: Result<Option<Vec<u8>>, Error> = db.get(b"k1");
-        assert_eq!(r.unwrap().unwrap(), b"v1111");
-        assert!(db.delete(b"k1").is_ok());
-        assert!(db.get(b"k1").unwrap().is_none());
-    }
-    let opts = Options::default();
-    let result = DB::destroy(&opts, path);
-    assert!(result.is_ok());
-}
-
-#[test]
-fn errors_do_stuff() {
-    let path = "_rust_rocksdb_error";
-    {
-        let _db = DB::open_default(path).unwrap();
-        let opts = Options::default();
-        // The DB will still be open when we try to destroy it and the lock should fail.
-        match DB::destroy(&opts, path) {
-            Err(s) => {
-                let message = s.to_string();
-                assert!(message.find("IO error:").is_some());
-                assert!(message.find("_rust_rocksdb_error/LOCK:").is_some());
-            }
-            Ok(_) => panic!("should fail"),
-        }
-    }
-    let opts = Options::default();
-    let result = DB::destroy(&opts, path);
-    assert!(result.is_ok());
-}
-
-#[test]
-fn writebatch_works() {
-    let path = "_rust_rocksdb_writebacktest";
-    {
-        let db = DB::open_default(path).unwrap();
-        {
-            // test putx
-            let mut batch = WriteBatch::default();
-            assert!(db.get(b"k1").unwrap().is_none());
-            assert_eq!(batch.len(), 0);
-            assert!(batch.is_empty());
-            batch.put(b"k1", b"v1111");
-            batch.put(b"k2", b"v2222");
-            batch.put(b"k3", b"v3333");
-            assert_eq!(batch.len(), 3);
-            assert!(!batch.is_empty());
-            assert!(db.get(b"k1").unwrap().is_none());
-            let p = db.write(batch);
-            assert!(p.is_ok());
-            let r: Result<Option<Vec<u8>>, Error> = db.get(b"k1");
-            assert_eq!(r.unwrap().unwrap(), b"v1111");
-        }
-        {
-            // test delete
-            let mut batch = WriteBatch::default();
-            batch.delete(b"k1");
-            assert_eq!(batch.len(), 1);
-            assert!(!batch.is_empty());
-            let p = db.write(batch);
-            assert!(p.is_ok());
-            assert!(db.get(b"k1").unwrap().is_none());
-        }
-        {
-            // test delete_range
-            let mut batch = WriteBatch::default();
-            batch.delete_range(b"k2", b"k4");
-            assert_eq!(batch.len(), 1);
-            assert!(!batch.is_empty());
-            let p = db.write(batch);
-            assert!(p.is_ok());
-            assert!(db.get(b"k2").unwrap().is_none());
-            assert!(db.get(b"k3").unwrap().is_none());
-        }
-        {
-            // test size_in_bytes
-            let mut batch = WriteBatch::default();
-            let before = batch.size_in_bytes();
-            batch.put(b"k1", b"v1234567890");
-            let after = batch.size_in_bytes();
-            assert!(before + 10 <= after);
-        }
-    }
-    let opts = Options::default();
-    assert!(DB::destroy(&opts, path).is_ok());
-}
-
-#[test]
-fn get_with_cache_and_bulkload_test() {
-    use crate::{BlockBasedOptions, Cache};
-
-    let path = "_rust_rocksdb_get_with_cache_and_bulkload_test";
-    let log_path = "_rust_rocksdb_log_path_test";
-    {
-        // create options
-        let mut opts = Options::default();
-        opts.create_if_missing(true);
-        opts.create_missing_column_families(true);
-        opts.set_wal_bytes_per_sync(8 << 10); // 8KB
-        opts.set_writable_file_max_buffer_size(512 << 10); // 512KB
-        opts.set_enable_write_thread_adaptive_yield(true);
-        opts.set_unordered_write(true);
-        opts.set_max_subcompactions(2);
-        opts.set_max_background_jobs(4);
-        opts.set_use_adaptive_mutex(true);
-
-        // set block based table and cache
-        let cache = Cache::new_lru_cache(64 << 10).unwrap();
-        let mut block_based_opts = BlockBasedOptions::default();
-        block_based_opts.set_block_cache(&cache);
-        block_based_opts.set_cache_index_and_filter_blocks(true);
-        opts.set_block_based_table_factory(&block_based_opts);
-
-        // open db
-        let db = DB::open(&opts, path).unwrap();
-
-        // write a lot
-        let mut batch = WriteBatch::default();
-        for i in 0..1_000 {
-            batch.put(format!("{:0>4}", i).as_bytes(), b"v");
-        }
-        assert!(db.write(batch).is_ok());
-
-        // flush memory table to sst, trigger cache usage on `get`
-        assert!(db.flush().is_ok());
-
-        // get -> trigger caching
-        let _ = db.get(b"1");
-        assert!(cache.get_usage() > 0);
-    }
-
-    // bulk loading
-    {
-        // create new options
-        let mut opts = Options::default();
-        opts.set_delete_obsolete_files_period_micros(100_000);
-        opts.prepare_for_bulk_load();
-        opts.set_db_log_dir(log_path);
-        opts.set_max_sequential_skip_in_iterations(16);
-
-        // open db
-        let db = DB::open(&opts, path).unwrap();
-
-        // try to get key
-        let iter = db.iterator(IteratorMode::Start);
-        for (expected, (k, _)) in iter.enumerate() {
-            assert_eq!(k.as_ref(), format!("{:0>4}", expected).as_bytes());
-        }
-    }
-
-    let opts = Options::default();
-    assert!(DB::destroy(&opts, path).is_ok());
-    assert!(DB::destroy(&opts, log_path).is_ok());
-}
-
-#[test]
-fn iterator_test() {
-    let path = "_rust_rocksdb_iteratortest";
-    {
-        let db = DB::open_default(path).unwrap();
-        let p = db.put(b"k1", b"v1111");
-        assert!(p.is_ok());
-        let p = db.put(b"k2", b"v2222");
-        assert!(p.is_ok());
-        let p = db.put(b"k3", b"v3333");
-        assert!(p.is_ok());
-        let iter = db.iterator(IteratorMode::Start);
-        for (k, v) in iter {
-            println!(
-                "Hello {}: {}",
-                str::from_utf8(&*k).unwrap(),
-                str::from_utf8(&*v).unwrap()
-            );
-        }
-    }
-    let opts = Options::default();
-    assert!(DB::destroy(&opts, path).is_ok());
-}
-
-#[test]
-fn iterator_test_past_end() {
-    let path = "_rust_rocksdb_iteratortest_past_end";
-    {
-        let db = DB::open_default(path).unwrap();
-        db.put(b"k1", b"v1111").unwrap();
-        let mut iter = db.iterator(IteratorMode::Start);
-        assert!(iter.next().is_some());
-        assert!(iter.next().is_none());
-        assert!(iter.next().is_none());
-    }
-    let opts = Options::default();
-    DB::destroy(&opts, path).unwrap();
-}
-
-#[test]
-fn iterator_test_upper_bound() {
-    let path = "_rust_rocksdb_iteratortest_upper_bound";
-    {
-        let db = DB::open_default(path).unwrap();
-        db.put(b"k1", b"v1").unwrap();
-        db.put(b"k2", b"v2").unwrap();
-        db.put(b"k3", b"v3").unwrap();
-        db.put(b"k4", b"v4").unwrap();
-        db.put(b"k5", b"v5").unwrap();
-
-        let mut readopts = ReadOptions::default();
-        readopts.set_iterate_upper_bound(b"k4".to_vec());
-
-        let iter = db.iterator_opt(IteratorMode::Start, readopts);
-        let expected: Vec<_> = vec![(b"k1", b"v1"), (b"k2", b"v2"), (b"k3", b"v3")]
-            .into_iter()
-            .map(|(k, v)| (k.to_vec().into_boxed_slice(), v.to_vec().into_boxed_slice()))
-            .collect();
-        assert_eq!(expected, iter.collect::<Vec<_>>());
-    }
-    let opts = Options::default();
-    DB::destroy(&opts, path).unwrap();
-}
-
-#[test]
-fn iterator_test_lower_bound() {
-    let path = "_rust_rocksdb_iteratortest_lower_bound";
-    {
-        let db = DB::open_default(path).unwrap();
-        db.put(b"k1", b"v1").unwrap();
-        db.put(b"k2", b"v2").unwrap();
-        db.put(b"k3", b"v3").unwrap();
-        db.put(b"k4", b"v4").unwrap();
-        db.put(b"k5", b"v5").unwrap();
-
-        let mut readopts = ReadOptions::default();
-        readopts.set_iterate_lower_bound(b"k4".to_vec());
-
-        let iter = db.iterator_opt(IteratorMode::Start, readopts);
-        let expected: Vec<_> = vec![(b"k4", b"v4"), (b"k5", b"v5")]
-            .into_iter()
-            .map(|(k, v)| (k.to_vec().into_boxed_slice(), v.to_vec().into_boxed_slice()))
-            .collect();
-        assert_eq!(expected, iter.collect::<Vec<_>>());
-    }
-    let opts = Options::default();
-    DB::destroy(&opts, path).unwrap();
-}
-
-#[test]
-fn prefix_extract_and_iterate_test() {
-    use crate::SliceTransform;
-
-    let path = "_rust_rocksdb_prefix_extract_and_iterate";
-    {
-        let mut opts = Options::default();
-        opts.create_if_missing(true);
-        opts.create_missing_column_families(true);
-        opts.set_prefix_extractor(SliceTransform::create_fixed_prefix(2));
-
-        let db = DB::open(&opts, path).unwrap();
-        db.put(b"p1_k1", b"v1").unwrap();
-        db.put(b"p2_k2", b"v2").unwrap();
-        db.put(b"p1_k3", b"v3").unwrap();
-        db.put(b"p1_k4", b"v4").unwrap();
-        db.put(b"p2_k5", b"v5").unwrap();
-
-        let mut readopts = ReadOptions::default();
-        readopts.set_prefix_same_as_start(true);
-        readopts.set_iterate_lower_bound(b"p1".to_vec());
-        readopts.set_pin_data(true);
-
-        let iter = db.iterator_opt(IteratorMode::Start, readopts);
-        let expected: Vec<_> = vec![(b"p1_k1", b"v1"), (b"p1_k3", b"v3"), (b"p1_k4", b"v4")]
-            .into_iter()
-            .map(|(k, v)| (k.to_vec().into_boxed_slice(), v.to_vec().into_boxed_slice()))
-            .collect();
-        assert_eq!(expected, iter.collect::<Vec<_>>());
-    }
-    let opts = Options::default();
-    DB::destroy(&opts, path).unwrap();
-}
-
-#[test]
-fn iterator_test_tailing() {
-    let path = "_rust_rocksdb_iteratortest_tailing";
-    {
-        let data = [(b"k1", b"v1"), (b"k2", b"v2"), (b"k3", b"v3")];
-        let mut ro = ReadOptions::default();
-        ro.set_tailing(true);
-        let db = DB::open_default(path).unwrap();
-
-        let mut data_iter = data.iter();
-        let (k, v) = data_iter.next().unwrap();
-        let r = db.put(k, v);
-        assert!(r.is_ok());
-
-        let tail_iter = db.iterator_opt(IteratorMode::Start, ro);
-        for (k, v) in data_iter {
-            let r = db.put(k, v);
-            assert!(r.is_ok());
-        }
-
-        let mut tot = 0;
-        for (i, (k, v)) in tail_iter.enumerate() {
-            assert_eq!(
-                (k.to_vec(), v.to_vec()),
-                (data[i].0.to_vec(), data[i].1.to_vec())
-            );
-            tot += 1;
-        }
-        assert_eq!(tot, data.len());
-    }
-    let opts = Options::default();
-    assert!(DB::destroy(&opts, path).is_ok());
-}
-
-#[test]
-fn snapshot_test() {
-    let path = "_rust_rocksdb_snapshottest";
-    {
-        let db = DB::open_default(path).unwrap();
-        let p = db.put(b"k1", b"v1111");
-        assert!(p.is_ok());
-
-        let snap = db.snapshot();
-        let r: Result<Option<Vec<u8>>, Error> = snap.get(b"k1");
-        assert_eq!(r.unwrap().unwrap(), b"v1111");
-
-        let p = db.put(b"k2", b"v2222");
-        assert!(p.is_ok());
-
-        assert!(db.get(b"k2").unwrap().is_some());
-        assert!(snap.get(b"k2").unwrap().is_none());
-    }
-    let opts = Options::default();
-    assert!(DB::destroy(&opts, path).is_ok());
-}
-
-#[test]
-fn set_option_test() {
-    let path = "_rust_rocksdb_set_optionstest";
-    {
-        let db = DB::open_default(path).unwrap();
-        // set an option to valid values
-        assert!(db
-            .set_options(&[("disable_auto_compactions", "true")])
-            .is_ok());
-        assert!(db
-            .set_options(&[("disable_auto_compactions", "false")])
-            .is_ok());
-        // invalid names/values should result in an error
-        assert!(db
-            .set_options(&[("disable_auto_compactions", "INVALID_VALUE")])
-            .is_err());
-        assert!(db
-            .set_options(&[("INVALID_NAME", "INVALID_VALUE")])
-            .is_err());
-        // option names/values must not contain NULLs
-        assert!(db
-            .set_options(&[("disable_auto_compactions", "true\0")])
-            .is_err());
-        assert!(db
-            .set_options(&[("disable_auto_compactions\0", "true")])
-            .is_err());
-        // empty options are not allowed
-        assert!(db.set_options(&[]).is_err());
-        // multiple options can be set in a single API call
-        let multiple_options = [
-            ("paranoid_file_checks", "true"),
-            ("report_bg_io_stats", "true"),
-        ];
-        db.set_options(&multiple_options).unwrap();
-    }
-    assert!(DB::destroy(&Options::default(), path).is_ok());
-}
-
-#[test]
-fn delete_range_test() {
-    let path = "_rust_rocksdb_delete_range_test";
-    {
-        let mut opts = Options::default();
-        opts.create_if_missing(true);
-        opts.create_missing_column_families(true);
-
-        let cfs = vec!["cf1"];
-        let db = DB::open_cf(&opts, path, cfs).unwrap();
-
-        let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
-        db.put_cf(cf1, b"k2", b"v2").unwrap();
-        db.put_cf(cf1, b"k3", b"v3").unwrap();
-        db.put_cf(cf1, b"k4", b"v4").unwrap();
-        db.put_cf(cf1, b"k5", b"v5").unwrap();
-
-        db.delete_range_cf(cf1, b"k2", b"k4").unwrap();
-        assert_eq!(db.get_cf(cf1, b"k1").unwrap().unwrap(), b"v1");
-        assert_eq!(db.get_cf(cf1, b"k4").unwrap().unwrap(), b"v4");
-        assert_eq!(db.get_cf(cf1, b"k5").unwrap().unwrap(), b"v5");
-        assert!(db.get_cf(cf1, b"k2").unwrap().is_none());
-        assert!(db.get_cf(cf1, b"k3").unwrap().is_none());
-    }
-    let opts = Options::default();
-    DB::destroy(&opts, path).unwrap();
-}
-
-#[test]
-fn compact_range_test() {
-    use crate::{
-        BottommostLevelCompaction, DBCompactionStyle, UniversalCompactOptions,
-        UniversalCompactionStopStyle,
-    };
-
-    let path = "_rust_rocksdb_compact_range_test";
-    {
-        let mut opts = Options::default();
-        opts.create_if_missing(true);
-        opts.create_missing_column_families(true);
-
-        // set compaction style
-        let mut uni_co_opts = UniversalCompactOptions::default();
-        uni_co_opts.set_size_ratio(2);
-        uni_co_opts.set_stop_style(UniversalCompactionStopStyle::Total);
-        opts.set_compaction_style(DBCompactionStyle::Universal);
-        opts.set_universal_compaction_options(&uni_co_opts);
-
-        // set compaction options
-        let mut compact_opts = CompactOptions::default();
-        compact_opts.set_exclusive_manual_compaction(true);
-        compact_opts.set_target_level(1);
-        compact_opts.set_change_level(true);
-        compact_opts.set_bottommost_level_compaction(BottommostLevelCompaction::ForceOptimized);
-
-        // put and compact column family cf1
-        let cfs = vec!["cf1"];
-        let db = DB::open_cf(&opts, path, cfs).unwrap();
-        let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
-        db.put_cf(cf1, b"k2", b"v2").unwrap();
-        db.put_cf(cf1, b"k3", b"v3").unwrap();
-        db.put_cf(cf1, b"k4", b"v4").unwrap();
-        db.put_cf(cf1, b"k5", b"v5").unwrap();
-        db.compact_range_cf(cf1, Some(b"k2"), Some(b"k4"));
-        db.compact_range_cf_opt(cf1, Some(b"k1"), None::<&str>, &compact_opts);
-
-        // put and compact default column family
-        db.put(b"k1", b"v1").unwrap();
-        db.put(b"k2", b"v2").unwrap();
-        db.put(b"k3", b"v3").unwrap();
-        db.put(b"k4", b"v4").unwrap();
-        db.put(b"k5", b"v5").unwrap();
-        db.compact_range(Some(b"k3"), None::<&str>);
-        db.compact_range_opt(None::<&str>, Some(b"k5"), &compact_opts);
-    }
-    let opts = Options::default();
-    DB::destroy(&opts, path).unwrap();
-}
-
-#[test]
-fn fifo_compaction_test() {
-    use crate::{DBCompactionStyle, FifoCompactOptions, PerfContext, PerfMetric};
-
-    let path = "_rust_rocksdb_fifo_compaction_test";
-    {
-        let mut opts = Options::default();
-        opts.create_if_missing(true);
-        opts.create_missing_column_families(true);
-
-        // set compaction style
-        let mut fifo_co_opts = FifoCompactOptions::default();
-        fifo_co_opts.set_max_table_files_size(4 << 10); // 4KB
-        opts.set_compaction_style(DBCompactionStyle::Fifo);
-        opts.set_fifo_compaction_options(&fifo_co_opts);
-
-        // put and compact column family cf1
-        let cfs = vec!["cf1"];
-        let db = DB::open_cf(&opts, path, cfs).unwrap();
-        let cf1 = db.cf_handle("cf1").unwrap();
-        db.put_cf(cf1, b"k1", b"v1").unwrap();
-        db.put_cf(cf1, b"k2", b"v2").unwrap();
-        db.put_cf(cf1, b"k3", b"v3").unwrap();
-        db.put_cf(cf1, b"k4", b"v4").unwrap();
-        db.put_cf(cf1, b"k5", b"v5").unwrap();
-        db.compact_range_cf(cf1, Some(b"k2"), Some(b"k4"));
-
-        // check stats
-        let ctx = PerfContext::default();
-
-        let block_cache_hit_count = ctx.metric(PerfMetric::BlockCacheHitCount);
-        assert!(block_cache_hit_count > 0);
-
-        let expect = format!("block_cache_hit_count = {}", block_cache_hit_count);
-        assert!(ctx.report(true).contains(&expect));
-    }
-    let opts = Options::default();
-    DB::destroy(&opts, path).unwrap();
-}
diff --git a/src/db_options.rs b/src/db_options.rs
index 64f5b74..52e5c7a 100644
--- a/src/db_options.rs
+++ b/src/db_options.rs
@@ -74,6 +74,104 @@ impl Drop for Cache {
     }
 }
 
+/// An Env is an interface used by the rocksdb implementation to access
+/// operating system functionality like the filesystem etc.  Callers
+/// may wish to provide a custom Env object when opening a database to
+/// get fine gain control; e.g., to rate limit file system operations.
+///
+/// All Env implementations are safe for concurrent access from
+/// multiple threads without any external synchronization.
+///
+/// Note: currently, C API behinds C++ API for various settings.
+/// See also: `rocksdb/include/env.h`
+pub struct Env {
+    pub(crate) inner: *mut ffi::rocksdb_env_t,
+}
+
+impl Drop for Env {
+    fn drop(&mut self) {
+        unsafe {
+            ffi::rocksdb_env_destroy(self.inner);
+        }
+    }
+}
+
+impl Env {
+    /// Returns default env
+    pub fn default() -> Result<Env, Error> {
+        let env = unsafe { ffi::rocksdb_create_default_env() };
+        if env.is_null() {
+            Err(Error::new("Could not create mem env".to_owned()))
+        } else {
+            Ok(Env { inner: env })
+        }
+    }
+
+    /// Returns a new environment that stores its data in memory and delegates
+    /// all non-file-storage tasks to base_env.
+    pub fn mem_env() -> Result<Env, Error> {
+        let env = unsafe { ffi::rocksdb_create_mem_env() };
+        if env.is_null() {
+            Err(Error::new("Could not create mem env".to_owned()))
+        } else {
+            Ok(Env { inner: env })
+        }
+    }
+
+    /// Sets the number of background worker threads of a specific thread pool for this environment.
+    /// `LOW` is the default pool.
+    ///
+    /// Default: 1
+    pub fn set_background_threads(&mut self, num_threads: c_int) {
+        unsafe {
+            ffi::rocksdb_env_set_background_threads(self.inner, num_threads);
+        }
+    }
+
+    /// Sets the size of the high priority thread pool that can be used to
+    /// prevent compactions from stalling memtable flushes.
+    pub fn set_high_priority_background_threads(&mut self, n: c_int) {
+        unsafe {
+            ffi::rocksdb_env_set_high_priority_background_threads(self.inner, n);
+        }
+    }
+
+    /// Wait for all threads started by StartThread to terminate.
+    pub fn join_all_threads(&mut self) {
+        unsafe {
+            ffi::rocksdb_env_join_all_threads(self.inner);
+        }
+    }
+
+    /// Lowering IO priority for threads from the specified pool.
+    pub fn lower_thread_pool_io_priority(&mut self) {
+        unsafe {
+            ffi::rocksdb_env_lower_thread_pool_io_priority(self.inner);
+        }
+    }
+
+    /// Lowering IO priority for high priority thread pool.
+    pub fn lower_high_priority_thread_pool_io_priority(&mut self) {
+        unsafe {
+            ffi::rocksdb_env_lower_high_priority_thread_pool_io_priority(self.inner);
+        }
+    }
+
+    /// Lowering CPU priority for threads from the specified pool.
+    pub fn lower_thread_pool_cpu_priority(&mut self) {
+        unsafe {
+            ffi::rocksdb_env_lower_thread_pool_cpu_priority(self.inner);
+        }
+    }
+
+    /// Lowering CPU priority for high priority thread pool.
+    pub fn lower_high_priority_thread_pool_cpu_priority(&mut self) {
+        unsafe {
+            ffi::rocksdb_env_lower_high_priority_thread_pool_cpu_priority(self.inner);
+        }
+    }
+}
+
 /// Database-wide options around performance and behavior.
 ///
 /// Please read the official tuning [guide](https://github.com/facebook/rocksdb/wiki/RocksDB-Tuning-Guide)
@@ -121,7 +219,7 @@ pub struct Options {
 /// ```
 /// use rocksdb::{DB, Options, WriteBatch, WriteOptions};
 ///
-/// let path = "_path_for_rocksdb_storageY";
+/// let path = "_path_for_rocksdb_storageY1";
 /// {
 ///     let db = DB::open_default(path).unwrap();
 ///     let mut batch = WriteBatch::default();
@@ -150,7 +248,7 @@ pub struct WriteOptions {
 /// ```
 /// use rocksdb::{DB, Options, FlushOptions};
 ///
-/// let path = "_path_for_rocksdb_storageY";
+/// let path = "_path_for_rocksdb_storageY2";
 /// {
 ///     let db = DB::open_default(path).unwrap();
 ///
@@ -191,11 +289,14 @@ pub struct ReadOptions {
 /// writer.put(b"k1", b"v1").unwrap();
 /// writer.finish().unwrap();
 ///
-/// let path = "_path_for_rocksdb_storageY";
-/// let db = DB::open_default(&path).unwrap();
-/// let mut ingest_opts = IngestExternalFileOptions::default();
-/// ingest_opts.set_move_files(true);
-/// db.ingest_external_file_opts(&ingest_opts, vec!["_path_for_sst_file"]).unwrap();
+/// let path = "_path_for_rocksdb_storageY3";
+/// {
+///   let db = DB::open_default(&path).unwrap();
+///   let mut ingest_opts = IngestExternalFileOptions::default();
+///   ingest_opts.set_move_files(true);
+///   db.ingest_external_file_opts(&ingest_opts, vec!["_path_for_sst_file"]).unwrap();
+/// }
+/// let _ = DB::destroy(&Options::default(), path);
 /// ```
 pub struct IngestExternalFileOptions {
     pub(crate) inner: *mut ffi::rocksdb_ingestexternalfileoptions_t,
@@ -618,6 +719,81 @@ impl Options {
         }
     }
 
+    /// Specifies whether an error should be raised if the database already exists.
+    ///
+    /// Default: false
+    pub fn set_error_if_exists(&mut self, enabled: bool) {
+        unsafe {
+            ffi::rocksdb_options_set_error_if_exists(self.inner, enabled as c_uchar);
+        }
+    }
+
+    /// Enable/disable paranoid checks.
+    ///
+    /// If true, the implementation will do aggressive checking of the
+    /// data it is processing and will stop early if it detects any
+    /// errors. This may have unforeseen ramifications: for example, a
+    /// corruption of one DB entry may cause a large number of entries to
+    /// become unreadable or for the entire DB to become unopenable.
+    /// If any of the  writes to the database fails (Put, Delete, Merge, Write),
+    /// the database will switch to read-only mode and fail all other
+    /// Write operations.
+    ///
+    /// Default: false
+    pub fn set_paranoid_checks(&mut self, enabled: bool) {
+        unsafe {
+            ffi::rocksdb_options_set_paranoid_checks(self.inner, enabled as c_uchar);
+        }
+    }
+
+    /// A list of paths where SST files can be put into, with its target size.
+    /// Newer data is placed into paths specified earlier in the vector while
+    /// older data gradually moves to paths specified later in the vector.
+    ///
+    /// For example, you have a flash device with 10GB allocated for the DB,
+    /// as well as a hard drive of 2TB, you should config it to be:
+    ///   [{"/flash_path", 10GB}, {"/hard_drive", 2TB}]
+    ///
+    /// The system will try to guarantee data under each path is close to but
+    /// not larger than the target size. But current and future file sizes used
+    /// by determining where to place a file are based on best-effort estimation,
+    /// which means there is a chance that the actual size under the directory
+    /// is slightly more than target size under some workloads. User should give
+    /// some buffer room for those cases.
+    ///
+    /// If none of the paths has sufficient room to place a file, the file will
+    /// be placed to the last path anyway, despite to the target size.
+    ///
+    /// Placing newer data to earlier paths is also best-efforts. User should
+    /// expect user files to be placed in higher levels in some extreme cases.
+    ///
+    /// If left empty, only one path will be used, which is `path` passed when
+    /// opening the DB.
+    ///
+    /// Default: empty
+    pub fn set_db_paths(&mut self, paths: &[DBPath]) {
+        let mut paths: Vec<_> = paths
+            .iter()
+            .map(|path| path.inner as *const ffi::rocksdb_dbpath_t)
+            .collect();
+        let num_paths = paths.len();
+        unsafe {
+            ffi::rocksdb_options_set_db_paths(self.inner, paths.as_mut_ptr(), num_paths);
+        }
+    }
+
+    /// Use the specified object to interact with the environment,
+    /// e.g. to read/write files, schedule background work, etc. In the near
+    /// future, support for doing storage operations such as read/write files
+    /// through env will be deprecated in favor of file_system.
+    ///
+    /// Default: Env::default()
+    pub fn set_env(&mut self, env: &Env) {
+        unsafe {
+            ffi::rocksdb_options_set_env(self.inner, env.inner);
+        }
+    }
+
     /// Sets the compression algorithm that will be used for compressing blocks.
     ///
     /// Default: `DBCompressionType::Snappy` (`DBCompressionType::None` if
@@ -3014,6 +3190,35 @@ impl CompactOptions {
     }
 }
 
+/// Represents a path where sst files can be put into
+pub struct DBPath {
+    pub(crate) inner: *mut ffi::rocksdb_dbpath_t,
+}
+
+impl DBPath {
+    /// Create a new path
+    pub fn new<P: AsRef<Path>>(path: P, target_size: u64) -> Result<Self, Error> {
+        let p = CString::new(path.as_ref().to_string_lossy().as_bytes()).unwrap();
+        let dbpath = unsafe { ffi::rocksdb_dbpath_create(p.as_ptr(), target_size) };
+        if dbpath.is_null() {
+            Err(Error::new(format!(
+                "Could not create path for storing sst files at location: {}",
+                path.as_ref().to_string_lossy()
+            )))
+        } else {
+            Ok(DBPath { inner: dbpath })
+        }
+    }
+}
+
+impl Drop for DBPath {
+    fn drop(&mut self) {
+        unsafe {
+            ffi::rocksdb_dbpath_destroy(self.inner);
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::{MemtableFactory, Options};
diff --git a/src/lib.rs b/src/lib.rs
index 37a7b10..5d6c017 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -97,7 +97,7 @@ pub use crate::{
     db_iterator::{DBIterator, DBRawIterator, DBWALIterator, Direction, IteratorMode},
     db_options::{
         BlockBasedIndexType, BlockBasedOptions, BottommostLevelCompaction, Cache, CompactOptions,
-        DBCompactionStyle, DBCompressionType, DBRecoveryMode, DataBlockIndexType,
+        DBCompactionStyle, DBCompressionType, DBPath, DBRecoveryMode, DataBlockIndexType, Env,
         FifoCompactOptions, FlushOptions, IngestExternalFileOptions, MemtableFactory, Options,
         PlainTableFactoryOptions, ReadOptions, UniversalCompactOptions,
         UniversalCompactionStopStyle, WriteOptions,
diff --git a/tests/test_db.rs b/tests/test_db.rs
index cae1b85..c97c2e5 100644
--- a/tests/test_db.rs
+++ b/tests/test_db.rs
@@ -14,7 +14,12 @@
 
 mod util;
 
-use rocksdb::{Error, IteratorMode, Options, Snapshot, WriteBatch, DB};
+use rocksdb::{
+    BlockBasedOptions, BottommostLevelCompaction, Cache, CompactOptions, DBCompactionStyle, Env,
+    Error, FifoCompactOptions, IteratorMode, Options, PerfContext, PerfMetric, ReadOptions,
+    SliceTransform, Snapshot, UniversalCompactOptions, UniversalCompactionStopStyle, WriteBatch,
+    DB,
+};
 use std::sync::Arc;
 use std::time::Duration;
 use std::{mem, thread};
@@ -85,10 +90,13 @@ fn writebatch_works() {
             assert_eq!(batch.len(), 0);
             assert!(batch.is_empty());
             batch.put(b"k1", b"v1111");
-            assert_eq!(batch.len(), 1);
+            batch.put(b"k2", b"v2222");
+            batch.put(b"k3", b"v3333");
+            assert_eq!(batch.len(), 3);
             assert!(!batch.is_empty());
             assert!(db.get(b"k1").unwrap().is_none());
-            assert!(db.write(batch).is_ok());
+            let p = db.write(batch);
+            assert!(p.is_ok());
             let r: Result<Option<Vec<u8>>, Error> = db.get(b"k1");
             assert_eq!(r.unwrap().unwrap(), b"v1111");
         }
@@ -98,9 +106,21 @@ fn writebatch_works() {
             batch.delete(b"k1");
             assert_eq!(batch.len(), 1);
             assert!(!batch.is_empty());
-            assert!(db.write(batch).is_ok());
+            let p = db.write(batch);
+            assert!(p.is_ok());
             assert!(db.get(b"k1").unwrap().is_none());
         }
+        {
+            // test delete_range
+            let mut batch = WriteBatch::default();
+            batch.delete_range(b"k2", b"k4");
+            assert_eq!(batch.len(), 1);
+            assert!(!batch.is_empty());
+            let p = db.write(batch);
+            assert!(p.is_ok());
+            assert!(db.get(b"k2").unwrap().is_none());
+            assert!(db.get(b"k3").unwrap().is_none());
+        }
         {
             // test size_in_bytes
             let mut batch = WriteBatch::default();
@@ -132,6 +152,97 @@ fn iterator_test() {
     }
 }
 
+#[test]
+fn iterator_test_past_end() {
+    let path = DBPath::new("_rust_rocksdb_iteratortest_past_end");
+    {
+        let db = DB::open_default(&path).unwrap();
+        db.put(b"k1", b"v1111").unwrap();
+        let mut iter = db.iterator(IteratorMode::Start);
+        assert!(iter.next().is_some());
+        assert!(iter.next().is_none());
+        assert!(iter.next().is_none());
+    }
+}
+
+#[test]
+fn iterator_test_tailing() {
+    let path = DBPath::new("_rust_rocksdb_iteratortest_tailing");
+    {
+        let data = [(b"k1", b"v1"), (b"k2", b"v2"), (b"k3", b"v3")];
+        let mut ro = ReadOptions::default();
+        ro.set_tailing(true);
+        let db = DB::open_default(&path).unwrap();
+
+        let mut data_iter = data.iter();
+        let (k, v) = data_iter.next().unwrap();
+        let r = db.put(k, v);
+        assert!(r.is_ok());
+
+        let tail_iter = db.iterator_opt(IteratorMode::Start, ro);
+        for (k, v) in data_iter {
+            let r = db.put(k, v);
+            assert!(r.is_ok());
+        }
+
+        let mut tot = 0;
+        for (i, (k, v)) in tail_iter.enumerate() {
+            assert_eq!(
+                (k.to_vec(), v.to_vec()),
+                (data[i].0.to_vec(), data[i].1.to_vec())
+            );
+            tot += 1;
+        }
+        assert_eq!(tot, data.len());
+    }
+}
+
+#[test]
+fn iterator_test_upper_bound() {
+    let path = DBPath::new("_rust_rocksdb_iteratortest_upper_bound");
+    {
+        let db = DB::open_default(&path).unwrap();
+        db.put(b"k1", b"v1").unwrap();
+        db.put(b"k2", b"v2").unwrap();
+        db.put(b"k3", b"v3").unwrap();
+        db.put(b"k4", b"v4").unwrap();
+        db.put(b"k5", b"v5").unwrap();
+
+        let mut readopts = ReadOptions::default();
+        readopts.set_iterate_upper_bound(b"k4".to_vec());
+
+        let iter = db.iterator_opt(IteratorMode::Start, readopts);
+        let expected: Vec<_> = vec![(b"k1", b"v1"), (b"k2", b"v2"), (b"k3", b"v3")]
+            .into_iter()
+            .map(|(k, v)| (k.to_vec().into_boxed_slice(), v.to_vec().into_boxed_slice()))
+            .collect();
+        assert_eq!(expected, iter.collect::<Vec<_>>());
+    }
+}
+
+#[test]
+fn iterator_test_lower_bound() {
+    let path = DBPath::new("_rust_rocksdb_iteratortest_lower_bound");
+    {
+        let db = DB::open_default(&path).unwrap();
+        db.put(b"k1", b"v1").unwrap();
+        db.put(b"k2", b"v2").unwrap();
+        db.put(b"k3", b"v3").unwrap();
+        db.put(b"k4", b"v4").unwrap();
+        db.put(b"k5", b"v5").unwrap();
+
+        let mut readopts = ReadOptions::default();
+        readopts.set_iterate_lower_bound(b"k4".to_vec());
+
+        let iter = db.iterator_opt(IteratorMode::Start, readopts);
+        let expected: Vec<_> = vec![(b"k4", b"v4"), (b"k5", b"v5")]
+            .into_iter()
+            .map(|(k, v)| (k.to_vec().into_boxed_slice(), v.to_vec().into_boxed_slice()))
+            .collect();
+        assert_eq!(expected, iter.collect::<Vec<_>>());
+    }
+}
+
 #[test]
 fn snapshot_test() {
     let path = DBPath::new("_rust_rocksdb_snapshottest");
@@ -374,3 +485,275 @@ fn test_open_with_ttl() {
     db.compact_range(None::<&[u8]>, None::<&[u8]>);
     assert!(db.get(b"key1").unwrap().is_none());
 }
+
+#[test]
+fn compact_range_test() {
+    let path = DBPath::new("_rust_rocksdb_compact_range_test");
+    {
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+
+        // set compaction style
+        let mut uni_co_opts = UniversalCompactOptions::default();
+        uni_co_opts.set_size_ratio(2);
+        uni_co_opts.set_stop_style(UniversalCompactionStopStyle::Total);
+        opts.set_compaction_style(DBCompactionStyle::Universal);
+        opts.set_universal_compaction_options(&uni_co_opts);
+
+        // set compaction options
+        let mut compact_opts = CompactOptions::default();
+        compact_opts.set_exclusive_manual_compaction(true);
+        compact_opts.set_target_level(1);
+        compact_opts.set_change_level(true);
+        compact_opts.set_bottommost_level_compaction(BottommostLevelCompaction::ForceOptimized);
+
+        // put and compact column family cf1
+        let cfs = vec!["cf1"];
+        let db = DB::open_cf(&opts, &path, cfs).unwrap();
+        let cf1 = db.cf_handle("cf1").unwrap();
+        db.put_cf(cf1, b"k1", b"v1").unwrap();
+        db.put_cf(cf1, b"k2", b"v2").unwrap();
+        db.put_cf(cf1, b"k3", b"v3").unwrap();
+        db.put_cf(cf1, b"k4", b"v4").unwrap();
+        db.put_cf(cf1, b"k5", b"v5").unwrap();
+        db.compact_range_cf(cf1, Some(b"k2"), Some(b"k4"));
+        db.compact_range_cf_opt(cf1, Some(b"k1"), None::<&str>, &compact_opts);
+
+        // put and compact default column family
+        db.put(b"k1", b"v1").unwrap();
+        db.put(b"k2", b"v2").unwrap();
+        db.put(b"k3", b"v3").unwrap();
+        db.put(b"k4", b"v4").unwrap();
+        db.put(b"k5", b"v5").unwrap();
+        db.compact_range(Some(b"k3"), None::<&str>);
+        db.compact_range_opt(None::<&str>, Some(b"k5"), &compact_opts);
+    }
+}
+
+#[test]
+fn fifo_compaction_test() {
+    let path = DBPath::new("_rust_rocksdb_fifo_compaction_test");
+    {
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+
+        // set compaction style
+        let mut fifo_co_opts = FifoCompactOptions::default();
+        fifo_co_opts.set_max_table_files_size(4 << 10); // 4KB
+        opts.set_compaction_style(DBCompactionStyle::Fifo);
+        opts.set_fifo_compaction_options(&fifo_co_opts);
+
+        // put and compact column family cf1
+        let cfs = vec!["cf1"];
+        let db = DB::open_cf(&opts, &path, cfs).unwrap();
+        let cf1 = db.cf_handle("cf1").unwrap();
+        db.put_cf(cf1, b"k1", b"v1").unwrap();
+        db.put_cf(cf1, b"k2", b"v2").unwrap();
+        db.put_cf(cf1, b"k3", b"v3").unwrap();
+        db.put_cf(cf1, b"k4", b"v4").unwrap();
+        db.put_cf(cf1, b"k5", b"v5").unwrap();
+        db.compact_range_cf(cf1, Some(b"k2"), Some(b"k4"));
+
+        // check stats
+        let ctx = PerfContext::default();
+
+        let block_cache_hit_count = ctx.metric(PerfMetric::BlockCacheHitCount);
+        assert!(block_cache_hit_count > 0);
+
+        let expect = format!("block_cache_hit_count = {}", block_cache_hit_count);
+        assert!(ctx.report(true).contains(&expect));
+    }
+}
+
+#[test]
+fn env_and_dbpaths_test() {
+    let path = DBPath::new("_rust_rocksdb_dbpath_test");
+    let path1 = DBPath::new("_rust_rocksdb_dbpath_test_1");
+    let path2 = DBPath::new("_rust_rocksdb_dbpath_test_2");
+    {
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+
+        let mut env = Env::default().unwrap();
+        env.lower_high_priority_thread_pool_cpu_priority();
+        opts.set_env(&env);
+
+        let mut paths = Vec::new();
+        paths.push(rocksdb::DBPath::new(&path1, 20 << 20).unwrap());
+        paths.push(rocksdb::DBPath::new(&path2, 30 << 20).unwrap());
+        opts.set_db_paths(&paths);
+
+        let db = DB::open(&opts, &path).unwrap();
+        db.put(b"k1", b"v1").unwrap();
+        assert_eq!(db.get(b"k1").unwrap().unwrap(), b"v1");
+    }
+}
+
+#[test]
+fn prefix_extract_and_iterate_test() {
+    let path = DBPath::new("_rust_rocksdb_prefix_extract_and_iterate");
+    {
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+        opts.set_prefix_extractor(SliceTransform::create_fixed_prefix(2));
+
+        let db = DB::open(&opts, &path).unwrap();
+        db.put(b"p1_k1", b"v1").unwrap();
+        db.put(b"p2_k2", b"v2").unwrap();
+        db.put(b"p1_k3", b"v3").unwrap();
+        db.put(b"p1_k4", b"v4").unwrap();
+        db.put(b"p2_k5", b"v5").unwrap();
+
+        let mut readopts = ReadOptions::default();
+        readopts.set_prefix_same_as_start(true);
+        readopts.set_iterate_lower_bound(b"p1".to_vec());
+        readopts.set_pin_data(true);
+
+        let iter = db.iterator_opt(IteratorMode::Start, readopts);
+        let expected: Vec<_> = vec![(b"p1_k1", b"v1"), (b"p1_k3", b"v3"), (b"p1_k4", b"v4")]
+            .into_iter()
+            .map(|(k, v)| (k.to_vec().into_boxed_slice(), v.to_vec().into_boxed_slice()))
+            .collect();
+        assert_eq!(expected, iter.collect::<Vec<_>>());
+    }
+}
+
+#[test]
+fn get_with_cache_and_bulkload_test() {
+    let path = DBPath::new("_rust_rocksdb_get_with_cache_and_bulkload_test");
+    let log_path = DBPath::new("_rust_rocksdb_log_path_test");
+    {
+        // create options
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+        opts.set_wal_bytes_per_sync(8 << 10); // 8KB
+        opts.set_writable_file_max_buffer_size(512 << 10); // 512KB
+        opts.set_enable_write_thread_adaptive_yield(true);
+        opts.set_unordered_write(true);
+        opts.set_max_subcompactions(2);
+        opts.set_max_background_jobs(4);
+        opts.set_use_adaptive_mutex(true);
+
+        // set block based table and cache
+        let cache = Cache::new_lru_cache(64 << 10).unwrap();
+        let mut block_based_opts = BlockBasedOptions::default();
+        block_based_opts.set_block_cache(&cache);
+        block_based_opts.set_cache_index_and_filter_blocks(true);
+        opts.set_block_based_table_factory(&block_based_opts);
+
+        // open db
+        let db = DB::open(&opts, &path).unwrap();
+
+        // write a lot
+        let mut batch = WriteBatch::default();
+        for i in 0..1_000 {
+            batch.put(format!("{:0>4}", i).as_bytes(), b"v");
+        }
+        assert!(db.write(batch).is_ok());
+
+        // flush memory table to sst, trigger cache usage on `get`
+        assert!(db.flush().is_ok());
+
+        // get -> trigger caching
+        let _ = db.get(b"1");
+        assert!(cache.get_usage() > 0);
+    }
+
+    // bulk loading
+    {
+        // create new options
+        let mut opts = Options::default();
+        opts.set_delete_obsolete_files_period_micros(100_000);
+        opts.prepare_for_bulk_load();
+        opts.set_db_log_dir(&log_path);
+        opts.set_max_sequential_skip_in_iterations(16);
+        opts.set_paranoid_checks(true);
+
+        // open db
+        let db = DB::open(&opts, &path).unwrap();
+
+        // try to get key
+        let iter = db.iterator(IteratorMode::Start);
+        for (expected, (k, _)) in iter.enumerate() {
+            assert_eq!(k.as_ref(), format!("{:0>4}", expected).as_bytes());
+        }
+    }
+
+    // raise error when db exists
+    {
+        // create new options
+        let mut opts = Options::default();
+        opts.set_error_if_exists(true);
+        assert!(DB::open(&opts, &path).is_err());
+    }
+}
+
+#[test]
+fn test_open_for_read_only() {
+    let path = DBPath::new("_rust_rocksdb_test_open_for_read_only");
+    {
+        let db = DB::open_default(&path).unwrap();
+        db.put(b"k1", b"v1").unwrap();
+    }
+    {
+        let opts = Options::default();
+        let error_if_log_file_exist = false;
+        let db = DB::open_for_read_only(&opts, &path, error_if_log_file_exist).unwrap();
+        assert_eq!(db.get(b"k1").unwrap().unwrap(), b"v1");
+        assert!(db.put(b"k2", b"v2").is_err());
+    }
+}
+
+#[test]
+fn test_open_cf_for_read_only() {
+    let path = DBPath::new("_rust_rocksdb_test_open_cf_for_read_only");
+    let cfs = vec!["cf1"];
+    {
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+        let db = DB::open_cf(&opts, &path, cfs.clone()).unwrap();
+        let cf1 = db.cf_handle("cf1").unwrap();
+        db.put_cf(cf1, b"k1", b"v1").unwrap();
+    }
+    {
+        let opts = Options::default();
+        let error_if_log_file_exist = false;
+        let db = DB::open_cf_for_read_only(&opts, &path, cfs, error_if_log_file_exist).unwrap();
+        let cf1 = db.cf_handle("cf1").unwrap();
+        assert_eq!(db.get_cf(cf1, b"k1").unwrap().unwrap(), b"v1");
+        assert!(db.put_cf(cf1, b"k2", b"v2").is_err());
+    }
+}
+
+#[test]
+fn delete_range_test() {
+    let path = DBPath::new("_rust_rocksdb_delete_range_test");
+    {
+        let mut opts = Options::default();
+        opts.create_if_missing(true);
+        opts.create_missing_column_families(true);
+
+        let cfs = vec!["cf1"];
+        let db = DB::open_cf(&opts, &path, cfs).unwrap();
+
+        let cf1 = db.cf_handle("cf1").unwrap();
+        db.put_cf(cf1, b"k1", b"v1").unwrap();
+        db.put_cf(cf1, b"k2", b"v2").unwrap();
+        db.put_cf(cf1, b"k3", b"v3").unwrap();
+        db.put_cf(cf1, b"k4", b"v4").unwrap();
+        db.put_cf(cf1, b"k5", b"v5").unwrap();
+
+        db.delete_range_cf(cf1, b"k2", b"k4").unwrap();
+        assert_eq!(db.get_cf(cf1, b"k1").unwrap().unwrap(), b"v1");
+        assert_eq!(db.get_cf(cf1, b"k4").unwrap().unwrap(), b"v4");
+        assert_eq!(db.get_cf(cf1, b"k5").unwrap().unwrap(), b"v5");
+        assert!(db.get_cf(cf1, b"k2").unwrap().is_none());
+        assert!(db.get_cf(cf1, b"k3").unwrap().is_none());
+    }
+}