feat: add a filterable count_rows to all the lancedb APIs (#913)

A `count_rows` method that takes a filter was recently added to
`LanceTable`. This PR adds it everywhere else except `RemoteTable` (that
will come soon).

node/src/index.ts

@@ -372,7 +372,7 @@ export interface Table<T = number[]> {
   /**
    * Returns the number of rows in this table.
    */
-  countRows: () => Promise<number>
+  countRows: (filter?: string) => Promise<number>
 
   /**
    * Delete rows from this table.
@@ -840,8 +840,8 @@ export class LocalTable<T = number[]> implements Table<T> {
   /**
    * Returns the number of rows in this table.
    */
-  async countRows (): Promise<number> {
-    return tableCountRows.call(this._tbl)
+  async countRows (filter?: string): Promise<number> {
+    return tableCountRows.call(this._tbl, filter)
   }
 
   /**

node/src/test/test.ts

@@ -294,6 +294,7 @@ describe('LanceDB client', function () {
       })
       assert.equal(table.name, 'vectors')
       assert.equal(await table.countRows(), 10)
+      assert.equal(await table.countRows('vector IS NULL'), 0)
       assert.deepEqual(await con.tableNames(), ['vectors'])
     })
 
@@ -369,6 +370,7 @@ describe('LanceDB client', function () {
       const table = await con.createTable('f16', data)
       assert.equal(table.name, 'f16')
       assert.equal(await table.countRows(), total)
+      assert.equal(await table.countRows('id < 5'), 5)
       assert.deepEqual(await con.tableNames(), ['f16'])
       assert.deepEqual(await table.schema, schema)