diff --git a/heed-traits/src/lib.rs b/heed-traits/src/lib.rs
index 88fb0efe..adf0c14a 100644
--- a/heed-traits/src/lib.rs
+++ b/heed-traits/src/lib.rs
@@ -9,9 +9,9 @@
 
 #![warn(missing_docs)]
 
-use std::borrow::Cow;
 use std::cmp::{Ord, Ordering};
 use std::error::Error as StdError;
+use std::io;
 
 /// A boxed `Send + Sync + 'static` error.
 pub type BoxedError = Box<dyn StdError + Send + Sync + 'static>;
@@ -21,8 +21,48 @@ pub trait BytesEncode<'a> {
     /// The type to encode.
     type EItem: ?Sized + 'a;
 
+    /// The type containing the encoded bytes.
+    type ReturnBytes: Into<Vec<u8>> + AsRef<[u8]> + 'a;
+
+    /// The error type to return when decoding goes wrong.
+    type Error: StdError + Send + Sync + 'static;
+
+    /// This function can be used to hint callers of the
+    /// [`bytes_encode`][BytesEncode::bytes_encode] function to use
+    /// [`bytes_encode_into_writer`][BytesEncode::bytes_encode_into_writer] instead, if the latter
+    /// runs faster (for example if it needs less heap allocations).
+    ///
+    /// The default implementation returns `true` because the default implementation of
+    /// [`bytes_encode_into_writer`][BytesEncode::bytes_encode_into_writer] is to forward to
+    /// [`bytes_encode`][BytesEncode::bytes_encode].
+    fn zero_copy(item: &Self::EItem) -> bool {
+        // This is preferred to renaming the function parameter (to _item) because IDEs can
+        // autofill trait implementations, which will default the paramter name to _item then and
+        // this could probably also mess with clippy's renamed_function_params lint.
+        let _ = item;
+
+        true
+    }
+
     /// Encode the given item as bytes.
-    fn bytes_encode(item: &'a Self::EItem) -> Result<Cow<'a, [u8]>, BoxedError>;
+    fn bytes_encode(item: &'a Self::EItem) -> Result<Self::ReturnBytes, Self::Error>;
+
+    /// Encode the given item as bytes and write it into the writer.
+    ///
+    /// When implementing this, also take a look at [`zero_copy`][BytesEncode::zero_copy]'s
+    /// documentation.
+    ///
+    /// The default implementation forwards to [`bytes_encode`][BytesEncode::bytes_encode].
+    fn bytes_encode_into_writer<W: io::Write>(
+        item: &'a Self::EItem,
+        mut writer: W,
+    ) -> Result<(), BoxedError> {
+        let bytes = Self::bytes_encode(item)?;
+
+        writer.write_all(bytes.as_ref())?;
+
+        Ok(())
+    }
 }
 
 /// A trait that represents a decoding structure.
diff --git a/heed-types/src/bytes.rs b/heed-types/src/bytes.rs
index ae602ba0..934357bd 100644
--- a/heed-types/src/bytes.rs
+++ b/heed-types/src/bytes.rs
@@ -1,4 +1,4 @@
-use std::borrow::Cow;
+use std::convert::Infallible;
 
 use heed_traits::{BoxedError, BytesDecode, BytesEncode};
 
@@ -11,8 +11,12 @@ pub enum Bytes {}
 impl<'a> BytesEncode<'a> for Bytes {
     type EItem = [u8];
 
-    fn bytes_encode(item: &'a Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        Ok(Cow::Borrowed(item))
+    type ReturnBytes = &'a [u8];
+
+    type Error = Infallible;
+
+    fn bytes_encode(item: &'a Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        Ok(item)
     }
 }
 
@@ -23,3 +27,26 @@ impl<'a> BytesDecode<'a> for Bytes {
         Ok(bytes)
     }
 }
+
+/// Like [`Bytes`], but always contains exactly `N` (the generic parameter) bytes.
+pub enum FixedSizeBytes<const N: usize> {}
+
+impl<'a, const N: usize> BytesEncode<'a> for FixedSizeBytes<N> {
+    type EItem = [u8; N];
+
+    type ReturnBytes = [u8; N]; // TODO &'a [u8; N] or [u8; N]
+
+    type Error = Infallible;
+
+    fn bytes_encode(item: &'a Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        Ok(*item)
+    }
+}
+
+impl<'a, const N: usize> BytesDecode<'a> for FixedSizeBytes<N> {
+    type DItem = [u8; N]; // TODO &'a [u8; N] or [u8; N]
+
+    fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, BoxedError> {
+        bytes.try_into().map_err(Into::into)
+    }
+}
diff --git a/heed-types/src/integer.rs b/heed-types/src/integer.rs
index 71435103..fd9a67de 100644
--- a/heed-types/src/integer.rs
+++ b/heed-types/src/integer.rs
@@ -1,4 +1,4 @@
-use std::borrow::Cow;
+use std::convert::Infallible;
 use std::marker::PhantomData;
 use std::mem::size_of;
 
@@ -11,8 +11,12 @@ pub struct U8;
 impl BytesEncode<'_> for U8 {
     type EItem = u8;
 
-    fn bytes_encode(item: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        Ok(Cow::from([*item].to_vec()))
+    type ReturnBytes = [u8; 1];
+
+    type Error = Infallible;
+
+    fn bytes_encode(item: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        Ok([*item])
     }
 }
 
@@ -30,8 +34,12 @@ pub struct I8;
 impl BytesEncode<'_> for I8 {
     type EItem = i8;
 
-    fn bytes_encode(item: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        Ok(Cow::from([*item as u8].to_vec()))
+    type ReturnBytes = [u8; 1];
+
+    type Error = Infallible;
+
+    fn bytes_encode(item: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        Ok([*item as u8])
     }
 }
 
@@ -54,10 +62,14 @@ macro_rules! define_type {
         impl<O: ByteOrder> BytesEncode<'_> for $name<O> {
             type EItem = $native;
 
-            fn bytes_encode(item: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-                let mut buf = vec![0; size_of::<Self::EItem>()];
+            type ReturnBytes = [u8; size_of::<$native>()];
+
+            type Error = Infallible;
+
+            fn bytes_encode(item: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+                let mut buf = [0; size_of::<$native>()];
                 O::$write_method(&mut buf, *item);
-                Ok(Cow::from(buf))
+                Ok(buf)
             }
         }
 
diff --git a/heed-types/src/serde_bincode.rs b/heed-types/src/serde_bincode.rs
index 37fefe01..d65ce05f 100644
--- a/heed-types/src/serde_bincode.rs
+++ b/heed-types/src/serde_bincode.rs
@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use heed_traits::{BoxedError, BytesDecode, BytesEncode};
 use serde::{Deserialize, Serialize};
 
@@ -14,8 +12,24 @@ where
 {
     type EItem = T;
 
-    fn bytes_encode(item: &'a Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        bincode::serialize(item).map(Cow::Owned).map_err(Into::into)
+    type ReturnBytes = Vec<u8>;
+
+    type Error = bincode::Error;
+
+    fn zero_copy(_item: &Self::EItem) -> bool {
+        false
+    }
+
+    fn bytes_encode(item: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        bincode::serialize(item)
+    }
+
+    fn bytes_encode_into_writer<W: std::io::Write>(
+        item: &'a Self::EItem,
+        writer: W,
+    ) -> Result<(), BoxedError> {
+        bincode::serialize_into(writer, item)?;
+        Ok(())
     }
 }
 
diff --git a/heed-types/src/serde_json.rs b/heed-types/src/serde_json.rs
index f1f1c3be..80624ff2 100644
--- a/heed-types/src/serde_json.rs
+++ b/heed-types/src/serde_json.rs
@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use heed_traits::{BoxedError, BytesDecode, BytesEncode};
 use serde::{Deserialize, Serialize};
 
@@ -14,8 +12,24 @@ where
 {
     type EItem = T;
 
-    fn bytes_encode(item: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        serde_json::to_vec(item).map(Cow::Owned).map_err(Into::into)
+    type ReturnBytes = Vec<u8>;
+
+    type Error = serde_json::Error;
+
+    fn zero_copy(_item: &Self::EItem) -> bool {
+        false
+    }
+
+    fn bytes_encode(item: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        serde_json::to_vec(item)
+    }
+
+    fn bytes_encode_into_writer<W: std::io::Write>(
+        item: &'a Self::EItem,
+        writer: W,
+    ) -> Result<(), BoxedError> {
+        serde_json::to_writer(writer, item)?;
+        Ok(())
     }
 }
 
diff --git a/heed-types/src/serde_rmp.rs b/heed-types/src/serde_rmp.rs
index f33c7467..00127131 100644
--- a/heed-types/src/serde_rmp.rs
+++ b/heed-types/src/serde_rmp.rs
@@ -1,5 +1,3 @@
-use std::borrow::Cow;
-
 use heed_traits::{BoxedError, BytesDecode, BytesEncode};
 use serde::{Deserialize, Serialize};
 
@@ -14,8 +12,24 @@ where
 {
     type EItem = T;
 
-    fn bytes_encode(item: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        rmp_serde::to_vec(item).map(Cow::Owned).map_err(Into::into)
+    type ReturnBytes = Vec<u8>;
+
+    type Error = rmp_serde::encode::Error;
+
+    fn zero_copy(_item: &Self::EItem) -> bool {
+        false
+    }
+
+    fn bytes_encode(item: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        rmp_serde::to_vec(item)
+    }
+
+    fn bytes_encode_into_writer<W: std::io::Write>(
+        item: &'a Self::EItem,
+        mut writer: W,
+    ) -> Result<(), BoxedError> {
+        rmp_serde::encode::write(&mut writer, item)?;
+        Ok(())
     }
 }
 
diff --git a/heed-types/src/str.rs b/heed-types/src/str.rs
index 220306d9..454ec6fd 100644
--- a/heed-types/src/str.rs
+++ b/heed-types/src/str.rs
@@ -1,16 +1,19 @@
-use std::borrow::Cow;
-use std::str;
+use std::convert::Infallible;
 
 use heed_traits::{BoxedError, BytesDecode, BytesEncode};
 
-/// Describes a [`prim@str`].
+/// Describes a [`str`].
 pub enum Str {}
 
-impl BytesEncode<'_> for Str {
+impl<'a> BytesEncode<'a> for Str {
     type EItem = str;
 
-    fn bytes_encode(item: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        Ok(Cow::Borrowed(item.as_bytes()))
+    type ReturnBytes = &'a [u8];
+
+    type Error = Infallible;
+
+    fn bytes_encode(item: &'a Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        Ok(item.as_bytes())
     }
 }
 
@@ -18,6 +21,6 @@ impl<'a> BytesDecode<'a> for Str {
     type DItem = &'a str;
 
     fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, BoxedError> {
-        str::from_utf8(bytes).map_err(Into::into)
+        std::str::from_utf8(bytes).map_err(Into::into)
     }
 }
diff --git a/heed-types/src/unit.rs b/heed-types/src/unit.rs
index 4fbb9e2c..a644ca4c 100644
--- a/heed-types/src/unit.rs
+++ b/heed-types/src/unit.rs
@@ -1,4 +1,4 @@
-use std::borrow::Cow;
+use std::convert::Infallible;
 use std::{error, fmt};
 
 use heed_traits::{BoxedError, BytesDecode, BytesEncode};
@@ -9,8 +9,12 @@ pub enum Unit {}
 impl BytesEncode<'_> for Unit {
     type EItem = ();
 
-    fn bytes_encode(_item: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-        Ok(Cow::Borrowed(&[]))
+    type ReturnBytes = [u8; 0];
+
+    type Error = Infallible;
+
+    fn bytes_encode(&(): &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+        Ok([])
     }
 }
 
diff --git a/heed/src/cookbook.rs b/heed/src/cookbook.rs
index f2cfd905..cb3b8e63 100644
--- a/heed/src/cookbook.rs
+++ b/heed/src/cookbook.rs
@@ -146,7 +146,7 @@
 //! to create codecs to encode prefixes when possible instead of using a slice of bytes.
 //!
 //! ```
-//! use std::borrow::Cow;
+//! use std::convert::Infallible;
 //! use std::error::Error;
 //! use std::fs;
 //! use std::path::Path;
@@ -154,7 +154,7 @@
 //! use heed::types::*;
 //! use heed::{BoxedError, BytesDecode, BytesEncode, Database, EnvOpenOptions};
 //!
-//! #[derive(Debug, PartialEq, Eq)]
+//! #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 //! pub enum Level {
 //!     Debug,
 //!     Warn,
@@ -172,18 +172,20 @@
 //! impl<'a> BytesEncode<'a> for LogKeyCodec {
 //!     type EItem = LogKey;
 //!
+//!     type ReturnBytes = [u8; 5];
+//!
+//!     type Error = Infallible;
+//!
 //!     /// Encodes the u32 timestamp in big endian followed by the log level with a single byte.
-//!     fn bytes_encode(log: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-//!         let (timestamp_bytes, level_byte) = match log {
-//!             LogKey { timestamp, level: Level::Debug } => (timestamp.to_be_bytes(), 0),
-//!             LogKey { timestamp, level: Level::Warn } => (timestamp.to_be_bytes(), 1),
-//!             LogKey { timestamp, level: Level::Error } => (timestamp.to_be_bytes(), 2),
-//!         };
+//!     fn bytes_encode(log: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+//!         let mut output = [0; 5];
 //!
-//!         let mut output = Vec::new();
-//!         output.extend_from_slice(&timestamp_bytes);
-//!         output.push(level_byte);
-//!         Ok(Cow::Owned(output))
+//!         let [timestamp @ .., level] = &mut output;
+//!
+//!         *timestamp = log.timestamp.to_be_bytes();
+//!         *level = log.level as u8;
+//!
+//!         Ok(output)
 //!     }
 //! }
 //!
@@ -218,9 +220,14 @@
 //! impl<'a> BytesEncode<'a> for LogAtHalfTimestampCodec {
 //!     type EItem = u32;
 //!
+//!     type ReturnBytes = [u8; 2];
+//!
+//!     type Error = Infallible;
+//!
 //!     /// This method encodes only the prefix of the keys in this particular case, the timestamp.
-//!     fn bytes_encode(half_timestamp: &Self::EItem) -> Result<Cow<[u8]>, BoxedError> {
-//!         Ok(Cow::Owned(half_timestamp.to_be_bytes()[..2].to_vec()))
+//!     fn bytes_encode(half_timestamp: &Self::EItem) -> Result<Self::ReturnBytes, Self::Error> {
+//!         let [bytes @ .., _, _] = half_timestamp.to_be_bytes();
+//!         Ok(bytes)
 //!     }
 //! }
 //!
diff --git a/heed/src/database.rs b/heed/src/database.rs
index 3817103f..a2e303b2 100644
--- a/heed/src/database.rs
+++ b/heed/src/database.rs
@@ -1,8 +1,7 @@
-use std::borrow::Cow;
 use std::ops::{Bound, RangeBounds};
 use std::{any, fmt, marker, mem, ptr};
 
-use heed_traits::{Comparator, LexicographicComparator};
+use heed_traits::{BytesEncode, Comparator, LexicographicComparator};
 use types::{DecodeIgnore, LazyDecode};
 
 use crate::cursor::MoveOperation;
@@ -346,9 +345,9 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
 
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
         let mut data_val = mem::MaybeUninit::uninit();
 
         let result = unsafe {
@@ -429,8 +428,8 @@ impl<KC, DC, C> Database<KC, DC, C> {
         assert_eq_env_db_txn!(self, txn);
 
         let mut cursor = RoCursor::new(txn, self.dbi)?;
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        if cursor.move_on_key(&key_bytes)? {
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        if cursor.move_on_key(key_bytes.as_ref())? {
             Ok(Some(RoIter::new(cursor)))
         } else {
             Ok(None)
@@ -493,8 +492,8 @@ impl<KC, DC, C> Database<KC, DC, C> {
         assert_eq_env_db_txn!(self, txn);
 
         let mut cursor = RoCursor::new(txn, self.dbi)?;
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        cursor.move_on_key_greater_than_or_equal_to(&key_bytes)?;
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        cursor.move_on_key_greater_than_or_equal_to(key_bytes.as_ref())?;
 
         match cursor.move_on_prev(MoveOperation::NoDup) {
             Ok(Some((key, data))) => match (KC::bytes_decode(key), DC::bytes_decode(data)) {
@@ -562,9 +561,10 @@ impl<KC, DC, C> Database<KC, DC, C> {
         assert_eq_env_db_txn!(self, txn);
 
         let mut cursor = RoCursor::new(txn, self.dbi)?;
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let result = match cursor.move_on_key_greater_than_or_equal_to(&key_bytes) {
-            Ok(Some((key, data))) if key == &key_bytes[..] => Ok(Some((key, data))),
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let key_bytes = key_bytes.as_ref();
+        let result = match cursor.move_on_key_greater_than_or_equal_to(key_bytes) {
+            Ok(Some((key, data))) if key == key_bytes => Ok(Some((key, data))),
             Ok(_) => cursor.move_on_prev(MoveOperation::NoDup),
             Err(e) => Err(e),
         };
@@ -635,9 +635,10 @@ impl<KC, DC, C> Database<KC, DC, C> {
         assert_eq_env_db_txn!(self, txn);
 
         let mut cursor = RoCursor::new(txn, self.dbi)?;
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let entry = match cursor.move_on_key_greater_than_or_equal_to(&key_bytes)? {
-            Some((key, data)) if key > &key_bytes[..] => Some((key, data)),
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let key_bytes = key_bytes.as_ref();
+        let entry = match cursor.move_on_key_greater_than_or_equal_to(key_bytes)? {
+            Some((key, data)) if key > key_bytes => Some((key, data)),
             Some((_key, _data)) => cursor.move_on_next(MoveOperation::NoDup)?,
             None => None,
         };
@@ -707,8 +708,8 @@ impl<KC, DC, C> Database<KC, DC, C> {
         assert_eq_env_db_txn!(self, txn);
 
         let mut cursor = RoCursor::new(txn, self.dbi)?;
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        match cursor.move_on_key_greater_than_or_equal_to(&key_bytes) {
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        match cursor.move_on_key_greater_than_or_equal_to(key_bytes.as_ref()) {
             Ok(Some((key, data))) => match (KC::bytes_decode(key), DC::bytes_decode(data)) {
                 (Ok(key), Ok(data)) => Ok(Some((key, data))),
                 (Err(e), _) | (_, Err(e)) => Err(Error::Decoding(e)),
@@ -1230,26 +1231,31 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
         let start_bound = match range.start_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
 
         let end_bound = match range.end_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
@@ -1322,26 +1328,31 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
         let start_bound = match range.start_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
 
         let end_bound = match range.end_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
@@ -1404,26 +1415,31 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
         let start_bound = match range.start_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
 
         let end_bound = match range.end_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
@@ -1496,26 +1512,31 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
         let start_bound = match range.start_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
 
         let end_bound = match range.end_bound() {
             Bound::Included(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Included(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Included(bytes.into())
             }
             Bound::Excluded(bound) => {
-                let bytes = KC::bytes_encode(bound).map_err(Error::Encoding)?;
-                Bound::Excluded(bytes.into_owned())
+                let bytes =
+                    KC::bytes_encode(bound).map_err(|err| Error::Encoding(Box::new(err)))?;
+                Bound::Excluded(bytes.into())
             }
             Bound::Unbounded => Bound::Unbounded,
         };
@@ -1579,8 +1600,10 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let prefix_bytes = KC::bytes_encode(prefix).map_err(Error::Encoding)?;
-        let prefix_bytes = prefix_bytes.into_owned();
+        let prefix_bytes =
+            KC::bytes_encode(prefix).map_err(|err| Error::Encoding(Box::new(err)))?;
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
+        let prefix_bytes = prefix_bytes.into();
         RoCursor::new(txn, self.dbi).map(|cursor| RoPrefix::new(cursor, prefix_bytes))
     }
 
@@ -1650,8 +1673,10 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let prefix_bytes = KC::bytes_encode(prefix).map_err(Error::Encoding)?;
-        let prefix_bytes = prefix_bytes.into_owned();
+        let prefix_bytes =
+            KC::bytes_encode(prefix).map_err(|err| Error::Encoding(Box::new(err)))?;
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
+        let prefix_bytes = prefix_bytes.into();
         RwCursor::new(txn, self.dbi).map(|cursor| RwPrefix::new(cursor, prefix_bytes))
     }
 
@@ -1711,8 +1736,10 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let prefix_bytes = KC::bytes_encode(prefix).map_err(Error::Encoding)?;
-        let prefix_bytes = prefix_bytes.into_owned();
+        let prefix_bytes =
+            KC::bytes_encode(prefix).map_err(|err| Error::Encoding(Box::new(err)))?;
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
+        let prefix_bytes = prefix_bytes.into();
         RoCursor::new(txn, self.dbi).map(|cursor| RoRevPrefix::new(cursor, prefix_bytes))
     }
 
@@ -1782,8 +1809,10 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let prefix_bytes = KC::bytes_encode(prefix).map_err(Error::Encoding)?;
-        let prefix_bytes = prefix_bytes.into_owned();
+        let prefix_bytes =
+            KC::bytes_encode(prefix).map_err(|err| Error::Encoding(Box::new(err)))?;
+        // TODO optimize, this might do unnecessary allocations on types that are already 'static
+        let prefix_bytes = prefix_bytes.into();
         RwCursor::new(txn, self.dbi).map(|cursor| RwRevPrefix::new(cursor, prefix_bytes))
     }
 
@@ -1829,11 +1858,11 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
 
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
-        let mut data_val = unsafe { crate::into_val(&data_bytes) };
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
+        let mut data_val = unsafe { crate::into_val(data_bytes.as_ref()) };
         let flags = 0;
 
         unsafe {
@@ -1892,8 +1921,8 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
         let mut reserved = ffi::reserve_size_val(data_size);
         let flags = ffi::MDB_RESERVE;
 
@@ -1982,11 +2011,11 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
 
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
-        let mut data_val = unsafe { crate::into_val(&data_bytes) };
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
+        let mut data_val = unsafe { crate::into_val(data_bytes.as_ref()) };
         let flags = flags.bits();
 
         unsafe {
@@ -2089,11 +2118,11 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
 
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
-        let mut data_val = unsafe { crate::into_val(&data_bytes) };
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
+        let mut data_val = unsafe { crate::into_val(data_bytes.as_ref()) };
         let flags = (flags | PutFlags::NO_OVERWRITE).bits();
 
         let result = unsafe {
@@ -2240,9 +2269,9 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
 
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
         let mut reserved = ffi::reserve_size_val(data_size);
         let flags = (flags | PutFlags::NO_OVERWRITE).bits() | lmdb_master_sys::MDB_RESERVE;
 
@@ -2320,8 +2349,8 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
 
         let result = unsafe {
             mdb_result(ffi::mdb_del(txn.txn.txn, self.dbi, &mut key_val, ptr::null_mut()))
@@ -2405,10 +2434,10 @@ impl<KC, DC, C> Database<KC, DC, C> {
     {
         assert_eq_env_db_txn!(self, txn);
 
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
-        let mut key_val = unsafe { crate::into_val(&key_bytes) };
-        let mut data_val = unsafe { crate::into_val(&data_bytes) };
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let mut key_val = unsafe { crate::into_val(key_bytes.as_ref()) };
+        let mut data_val = unsafe { crate::into_val(data_bytes.as_ref()) };
 
         let result =
             unsafe { mdb_result(ffi::mdb_del(txn.txn.txn, self.dbi, &mut key_val, &mut data_val)) };
diff --git a/heed/src/iterator/iter.rs b/heed/src/iterator/iter.rs
index 87f67662..a8da8198 100644
--- a/heed/src/iterator/iter.rs
+++ b/heed/src/iterator/iter.rs
@@ -1,6 +1,6 @@
-use std::borrow::Cow;
 use std::marker;
 
+use heed_traits::BytesEncode;
 use types::LazyDecode;
 
 use crate::iteration_method::{IterationMethod, MoveBetweenKeys, MoveThroughDuplicateValues};
@@ -272,9 +272,9 @@ impl<'txn, KC, DC, IM> RwIter<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         DC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current(&key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current(key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Write a new value to the current entry. The entry is written with the specified flags.
@@ -301,8 +301,13 @@ impl<'txn, KC, DC, IM> RwIter<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         F: FnOnce(&mut ReservedSpace) -> io::Result<()>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        self.cursor.put_current_reserved_with_flags(flags, &key_bytes, data_size, write_func)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_reserved_with_flags(
+            flags,
+            key_bytes.as_ref(),
+            data_size,
+            write_func,
+        )
     }
 
     /// Insert a key-value pair in this database. The entry is written with the specified flags and data codec.
@@ -332,9 +337,9 @@ impl<'txn, KC, DC, IM> RwIter<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         NDC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = NDC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current_with_flags(flags, &key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = NDC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_with_flags(flags, key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Move on the first value of keys, ignoring duplicate values.
@@ -621,9 +626,9 @@ impl<'txn, KC, DC, IM> RwRevIter<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         DC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current(&key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current(key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Write a new value to the current entry. The entry is written with the specified flags.
@@ -650,8 +655,13 @@ impl<'txn, KC, DC, IM> RwRevIter<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         F: FnOnce(&mut ReservedSpace) -> io::Result<()>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        self.cursor.put_current_reserved_with_flags(flags, &key_bytes, data_size, write_func)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_reserved_with_flags(
+            flags,
+            key_bytes.as_ref(),
+            data_size,
+            write_func,
+        )
     }
 
     /// Insert a key-value pair in this database. The entry is written with the specified flags and data codec.
@@ -681,9 +691,9 @@ impl<'txn, KC, DC, IM> RwRevIter<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         NDC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = NDC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current_with_flags(flags, &key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = NDC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_with_flags(flags, key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Move on the first value of keys, ignoring duplicate values.
diff --git a/heed/src/iterator/prefix.rs b/heed/src/iterator/prefix.rs
index fabd2f49..5d85a828 100644
--- a/heed/src/iterator/prefix.rs
+++ b/heed/src/iterator/prefix.rs
@@ -1,4 +1,3 @@
-use std::borrow::Cow;
 use std::marker;
 
 use heed_traits::LexicographicComparator;
@@ -265,9 +264,9 @@ impl<'txn, KC, DC, C, IM> RwPrefix<'txn, KC, DC, C, IM> {
         KC: BytesEncode<'a>,
         DC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current(&key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current(key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Write a new value to the current entry. The entry is written with the specified flags.
@@ -294,8 +293,13 @@ impl<'txn, KC, DC, C, IM> RwPrefix<'txn, KC, DC, C, IM> {
         KC: BytesEncode<'a>,
         F: FnOnce(&mut ReservedSpace) -> io::Result<()>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        self.cursor.put_current_reserved_with_flags(flags, &key_bytes, data_size, write_func)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_reserved_with_flags(
+            flags,
+            key_bytes.as_ref(),
+            data_size,
+            write_func,
+        )
     }
 
     /// Insert a key-value pair in this database. The entry is written with the specified flags and data codec.
@@ -325,9 +329,9 @@ impl<'txn, KC, DC, C, IM> RwPrefix<'txn, KC, DC, C, IM> {
         KC: BytesEncode<'a>,
         NDC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = NDC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current_with_flags(flags, &key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = NDC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_with_flags(flags, key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Move on the first value of keys, ignoring duplicate values.
@@ -655,9 +659,9 @@ impl<'txn, KC, DC, C, IM> RwRevPrefix<'txn, KC, DC, C, IM> {
         KC: BytesEncode<'a>,
         DC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current(&key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current(key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Write a new value to the current entry. The entry is written with the specified flags.
@@ -684,8 +688,13 @@ impl<'txn, KC, DC, C, IM> RwRevPrefix<'txn, KC, DC, C, IM> {
         KC: BytesEncode<'a>,
         F: FnOnce(&mut ReservedSpace) -> io::Result<()>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        self.cursor.put_current_reserved_with_flags(flags, &key_bytes, data_size, write_func)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_reserved_with_flags(
+            flags,
+            key_bytes.as_ref(),
+            data_size,
+            write_func,
+        )
     }
 
     /// Insert a key-value pair in this database. The entry is written with the specified flags and data codec.
@@ -715,9 +724,9 @@ impl<'txn, KC, DC, C, IM> RwRevPrefix<'txn, KC, DC, C, IM> {
         KC: BytesEncode<'a>,
         NDC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = NDC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current_with_flags(flags, &key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = NDC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_with_flags(flags, key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Move on the first value of keys, ignoring duplicate values.
diff --git a/heed/src/iterator/range.rs b/heed/src/iterator/range.rs
index c6dc99c4..cdd5751a 100644
--- a/heed/src/iterator/range.rs
+++ b/heed/src/iterator/range.rs
@@ -1,4 +1,3 @@
-use std::borrow::Cow;
 use std::marker;
 use std::ops::Bound;
 
@@ -274,9 +273,9 @@ impl<'txn, KC, DC, IM> RwRange<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         DC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current(&key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current(key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Write a new value to the current entry. The entry is written with the specified flags.
@@ -303,8 +302,13 @@ impl<'txn, KC, DC, IM> RwRange<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         F: FnOnce(&mut ReservedSpace) -> io::Result<()>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        self.cursor.put_current_reserved_with_flags(flags, &key_bytes, data_size, write_func)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_reserved_with_flags(
+            flags,
+            key_bytes.as_ref(),
+            data_size,
+            write_func,
+        )
     }
 
     /// Insert a key-value pair in this database. The entry is written with the specified flags and data codec.
@@ -334,9 +338,9 @@ impl<'txn, KC, DC, IM> RwRange<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         NDC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = NDC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current_with_flags(flags, &key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = NDC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_with_flags(flags, key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Move on the first value of keys, ignoring duplicate values.
@@ -711,9 +715,9 @@ impl<'txn, KC, DC, IM> RwRevRange<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         DC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = DC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current(&key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = DC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current(key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Write a new value to the current entry. The entry is written with the specified flags.
@@ -740,8 +744,13 @@ impl<'txn, KC, DC, IM> RwRevRange<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         F: FnOnce(&mut ReservedSpace) -> io::Result<()>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        self.cursor.put_current_reserved_with_flags(flags, &key_bytes, data_size, write_func)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_reserved_with_flags(
+            flags,
+            key_bytes.as_ref(),
+            data_size,
+            write_func,
+        )
     }
 
     /// Insert a key-value pair in this database. The entry is written with the specified flags and data codec.
@@ -771,9 +780,9 @@ impl<'txn, KC, DC, IM> RwRevRange<'txn, KC, DC, IM> {
         KC: BytesEncode<'a>,
         NDC: BytesEncode<'a>,
     {
-        let key_bytes: Cow<[u8]> = KC::bytes_encode(key).map_err(Error::Encoding)?;
-        let data_bytes: Cow<[u8]> = NDC::bytes_encode(data).map_err(Error::Encoding)?;
-        self.cursor.put_current_with_flags(flags, &key_bytes, &data_bytes)
+        let key_bytes = KC::bytes_encode(key).map_err(|err| Error::Encoding(Box::new(err)))?;
+        let data_bytes = NDC::bytes_encode(data).map_err(|err| Error::Encoding(Box::new(err)))?;
+        self.cursor.put_current_with_flags(flags, key_bytes.as_ref(), data_bytes.as_ref())
     }
 
     /// Move on the first value of keys, ignoring duplicate values.