feat: remote index stats (#1702)

BREAKING CHANGE: the return value of `index_stats` method has changed
and all `index_stats` APIs now take index name instead of UUID. Also
several deprecated index statistics methods were removed.

* Removes deprecated methods for individual index statistics
* Aligns public `IndexStatistics` struct with API response from LanceDB
Cloud.
* Implements `index_stats` for remote Rust SDK and Python async API.

python/src/index.rs

@@ -200,6 +200,8 @@ pub struct IndexConfig {
     /// Currently this is always a list of size 1.  In the future there may
     /// be more columns to represent composite indices.
     pub columns: Vec<String>,
+    /// Name of the index.
+    pub name: String,
 }
 
 #[pymethods]
@@ -215,6 +217,7 @@ impl From<lancedb::index::IndexConfig> for IndexConfig {
         Self {
             index_type,
             columns: value.columns,
+            name: value.name,
         }
     }
 }

python/src/table.rs

@@ -8,8 +8,8 @@ use lancedb::table::{
 use pyo3::{
     exceptions::{PyRuntimeError, PyValueError},
     pyclass, pymethods,
-    types::{PyDict, PyString},
-    Bound, PyAny, PyRef, PyResult, Python,
+    types::{PyDict, PyDictMethods, PyString},
+    Bound, PyAny, PyRef, PyResult, Python, ToPyObject,
 };
 use pyo3_asyncio_0_21::tokio::future_into_py;
 
@@ -204,6 +204,33 @@ impl Table {
         })
     }
 
+    pub fn index_stats(self_: PyRef<'_, Self>, index_name: String) -> PyResult<Bound<'_, PyAny>> {
+        let inner = self_.inner_ref()?.clone();
+        future_into_py(self_.py(), async move {
+            let stats = inner.index_stats(&index_name).await.infer_error()?;
+            if let Some(stats) = stats {
+                Python::with_gil(|py| {
+                    let dict = PyDict::new_bound(py);
+                    dict.set_item("num_indexed_rows", stats.num_indexed_rows)?;
+                    dict.set_item("num_unindexed_rows", stats.num_unindexed_rows)?;
+                    dict.set_item("index_type", stats.index_type.to_string())?;
+
+                    if let Some(distance_type) = stats.distance_type {
+                        dict.set_item("distance_type", distance_type.to_string())?;
+                    }
+
+                    if let Some(num_indices) = stats.num_indices {
+                        dict.set_item("num_indices", num_indices)?;
+                    }
+
+                    Ok(Some(dict.to_object(py)))
+                })
+            } else {
+                Ok(None)
+            }
+        })
+    }
+
     pub fn __repr__(&self) -> String {
         match &self.inner {
             None => format!("ClosedTable({})", self.name),