diff --git a/chir-rs-castore/src/lib.rs b/chir-rs-castore/src/lib.rs
index 1d438ac..db794d3 100644
--- a/chir-rs-castore/src/lib.rs
+++ b/chir-rs-castore/src/lib.rs
@@ -15,7 +15,7 @@ use chir_rs_config::ChirRs;
 use chir_rs_misc::{id_generator, lexicographic_base64};
 use educe::Educe;
 use eyre::{Context as _, Result};
-use stretto::{AsyncCache, AsyncCacheBuilder};
+use stretto::AsyncCache;
 use tokio::{
     fs::read_to_string,
     io::{AsyncRead, AsyncReadExt},
diff --git a/chir-rs-db/.sqlx/query-4eb1d9d2853313df1b2a2050de46d609d719ce7cf906df70d693ffc186468351.json b/chir-rs-db/.sqlx/query-4eb1d9d2853313df1b2a2050de46d609d719ce7cf906df70d693ffc186468351.json
new file mode 100644
index 0000000..a82c7a8
--- /dev/null
+++ b/chir-rs-db/.sqlx/query-4eb1d9d2853313df1b2a2050de46d609d719ce7cf906df70d693ffc186468351.json
@@ -0,0 +1,22 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "SELECT COUNT(*) as amount FROM file_map WHERE \"b3hash\" = $1",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "amount",
+        "type_info": "Int8"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "Bytea"
+      ]
+    },
+    "nullable": [
+      null
+    ]
+  },
+  "hash": "4eb1d9d2853313df1b2a2050de46d609d719ce7cf906df70d693ffc186468351"
+}
diff --git a/chir-rs-db/migrations/20241130081151_add-file-b3hash-index.sql b/chir-rs-db/migrations/20241130081151_add-file-b3hash-index.sql
new file mode 100644
index 0000000..4b3dc39
--- /dev/null
+++ b/chir-rs-db/migrations/20241130081151_add-file-b3hash-index.sql
@@ -0,0 +1,3 @@
+-- Add migration script here
+
+create index file_b3hash on file_map(b3hash);
\ No newline at end of file
diff --git a/chir-rs-db/src/file.rs b/chir-rs-db/src/file.rs
index 72e7a57..1ff7d3a 100644
--- a/chir-rs-db/src/file.rs
+++ b/chir-rs-db/src/file.rs
@@ -208,7 +208,7 @@ impl File {
     /// Updates the file with new information
     ///
     /// # Errors
-    /// THis function returns an error if updating the entry in the database fails
+    /// This function returns an error if updating the entry in the database fails
     #[instrument(skip(db))]
     pub async fn update(&self, db: &Database) -> Result<()> {
         let id: i64 = self.id.try_into()?;
@@ -231,4 +231,22 @@ impl File {
         })?;
         Ok(())
     }
+
+    /// Checks if a particular hash is in use
+    ///
+    /// # Errors
+    /// This function returns an error if updating the entry in the database fails
+    #[instrument(skip(db))]
+    pub async fn is_used(db: &Database, hash: Hash) -> Result<bool> {
+        #[expect(clippy::panic, reason = "sqlx silliness")]
+        let count = query!(
+            r#"SELECT COUNT(*) as amount FROM file_map WHERE "b3hash" = $1"#,
+            hash.as_bytes()
+        )
+        .fetch_one(&*db.0)
+        .await
+        .with_context(|| format!("Checking if {hash:?} is still used."))?;
+
+        Ok(count.amount.unwrap_or_default() != 0)
+    }
 }