From 2f561c77f528d3ba44c7b1f71575e86781c42a1b Mon Sep 17 00:00:00 2001
From: Kerollmops <clement@meilisearch.com>
Date: Thu, 18 Feb 2021 14:35:14 +0100
Subject: [PATCH] Introduce the word documents count method on the index

---
 milli/src/index.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/milli/src/index.rs b/milli/src/index.rs
index f8efa324e..5c5fc9895 100644
--- a/milli/src/index.rs
+++ b/milli/src/index.rs
@@ -352,6 +352,17 @@ impl Index {
         }
     }
 
+    /* word documents count */
+
+    /// Returns the number of documents ids associated with the given word,
+    /// it is much faster than deserializing the bitmap and getting the length of it.
+    pub fn word_documents_count(&self, rtxn: &RoTxn, word: &str) -> anyhow::Result<Option<u64>> {
+        self.word_docids
+            .remap_data_type::<RoaringBitmapLenCodec>()
+            .get(rtxn, word)
+            .map_err(Into::into)
+    }
+
     /* documents */
 
     /// Returns a [`Vec`] of the requested documents. Returns an error if a document is missing.