diff --git a/src/facet/facet_type.rs b/src/facet/facet_type.rs
index 93c98316d..4fdc80798 100644
--- a/src/facet/facet_type.rs
+++ b/src/facet/facet_type.rs
@@ -1,17 +1,50 @@
-use std::cmp;
+use std::error::Error;
+use std::fmt;
+use std::str::FromStr;
+
 use serde::{Serialize, Deserialize};
 
 #[derive(Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq, Hash)]
 #[derive(Serialize, Deserialize)]
 pub enum FacetType {
     String,
-    F64,
-    I64,
-    U64,
+    Float,
+    Integer,
 }
 
-impl FacetType {
-    pub fn merge(a: FacetType, b: FacetType) -> FacetType {
-        cmp::min(a, b)
+impl fmt::Display for FacetType {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            FacetType::String => f.write_str("string"),
+            FacetType::Float => f.write_str("float"),
+            FacetType::Integer => f.write_str("integer"),
+        }
     }
 }
+
+impl FromStr for FacetType {
+    type Err = InvalidFacetType;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if s.eq_ignore_ascii_case("string") {
+            Ok(FacetType::String)
+        } else if s.eq_ignore_ascii_case("float") {
+            Ok(FacetType::Float)
+        } else if s.eq_ignore_ascii_case("integer") {
+            Ok(FacetType::Integer)
+        } else {
+            Err(InvalidFacetType)
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq, Hash)]
+pub struct InvalidFacetType;
+
+impl fmt::Display for InvalidFacetType {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(r#"Invalid facet type, must be "string", "float" or "integer""#)
+    }
+}
+
+impl Error for InvalidFacetType { }
diff --git a/src/facet/value_encoding.rs b/src/facet/value_encoding.rs
index 01fdba723..3cb012a0e 100644
--- a/src/facet/value_encoding.rs
+++ b/src/facet/value_encoding.rs
@@ -13,16 +13,6 @@ pub fn f64_into_bytes(float: f64) -> Option<[u8; 8]> {
     None
 }
 
-#[inline]
-pub fn u64_into_bytes(int: u64) -> [u8; 8] {
-    int.to_be_bytes()
-}
-
-#[inline]
-pub fn u64_from_bytes(bytes: [u8; 8]) -> u64 {
-    u64::from_be_bytes(bytes)
-}
-
 #[inline]
 pub fn i64_into_bytes(int: i64) -> [u8; 8] {
     xor_first_bit(int.to_be_bytes())
@@ -66,16 +56,6 @@ mod tests {
         assert!(is_sorted(&vec), "{:?}", vec);
     }
 
-    #[test]
-    fn ordered_u64_bytes() {
-        let a = 0_u64;
-        let b = 1_u64;
-        let c = 43_u64;
-
-        let vec: Vec<_> = [a, b, c].iter().cloned().map(u64_into_bytes).collect();
-        assert!(is_sorted(&vec), "{:?}", vec);
-    }
-
     #[test]
     fn ordered_i64_bytes() {
         let a = -10_i64;
diff --git a/src/heed_codec/facet/facet_value_u64_codec.rs b/src/heed_codec/facet/facet_value_u64_codec.rs
deleted file mode 100644
index 2fdc7416e..000000000
--- a/src/heed_codec/facet/facet_value_u64_codec.rs
+++ /dev/null
@@ -1,28 +0,0 @@
-use std::borrow::Cow;
-use std::convert::TryInto;
-use std::str;
-
-use crate::heed_codec::StrBytesCodec;
-use crate::facet::value_encoding::{u64_from_bytes, u64_into_bytes};
-
-pub struct FacetValueU64Codec;
-
-impl<'a> heed::BytesDecode<'a> for FacetValueU64Codec {
-    type DItem = (&'a str, u64);
-
-    fn bytes_decode(bytes: &'a [u8]) -> Option<Self::DItem> {
-        let (name, bytes) = StrBytesCodec::bytes_decode(bytes)?;
-        let value = bytes.try_into().map(u64_from_bytes).ok()?;
-        Some((name, value))
-    }
-}
-
-impl<'a> heed::BytesEncode<'a> for FacetValueU64Codec {
-    type EItem = (&'a str, u64);
-
-    fn bytes_encode((name, value): &Self::EItem) -> Option<Cow<[u8]>> {
-        let value = u64_into_bytes(*value);
-        let tuple = (*name, &value[..]);
-        StrBytesCodec::bytes_encode(&tuple).map(Cow::into_owned).map(Cow::Owned)
-    }
-}
diff --git a/src/heed_codec/facet/mod.rs b/src/heed_codec/facet/mod.rs
index ba34f6220..abe2c1d8a 100644
--- a/src/heed_codec/facet/mod.rs
+++ b/src/heed_codec/facet/mod.rs
@@ -1,9 +1,7 @@
 mod facet_value_f64_codec;
 mod facet_value_i64_codec;
 mod facet_value_string_codec;
-mod facet_value_u64_codec;
 
 pub use self::facet_value_f64_codec::FacetValueF64Codec;
 pub use self::facet_value_i64_codec::FacetValueI64Codec;
 pub use self::facet_value_string_codec::FacetValueStringCodec;
-pub use self::facet_value_u64_codec::FacetValueU64Codec;