TypeScript modules: Expose hash indices (#4233)

# Description of Changes

This allows `.index('hash')`.

# API and ABI breaking changes

None

# Expected complexity level and risk

1

# Testing

Verified that it works using the keynote 2 benchmark.

Author: Centril

crates/bindings-typescript/src/lib/indexes.ts

@@ -12,6 +12,7 @@ export type IndexOpts<AllowedCol extends string> = {
   name?: string;
 } & (
   | { algorithm: 'btree'; columns: readonly AllowedCol[] }
+  | { algorithm: 'hash'; columns: readonly AllowedCol[] }
   | { algorithm: 'direct'; column: AllowedCol }
 );
 
@@ -21,7 +22,7 @@ export type IndexOpts<AllowedCol extends string> = {
 export type UntypedIndex<AllowedCol extends string> = {
   name: string;
   unique?: boolean;
-  algorithm: 'btree' | 'direct';
+  algorithm: 'btree' | 'direct' | 'hash';
   columns: readonly AllowedCol[];
 };
 
@@ -47,14 +48,17 @@ export type Indexes<
 };
 
 /**
- * A type representing a database index, which can be either unique or ranged.
+ * A type representing a database index,
+ * which can either be unique or filter for a single value or range of values.
  */
 export type Index<
   TableDef extends UntypedTableDef,
   I extends UntypedIndex<keyof TableDef['columns'] & string>,
 > = I['unique'] extends true
   ? UniqueIndex<TableDef, I>
-  : RangedIndex<TableDef, I>;
+  : I['algorithm'] extends 'hash'
+    ? PointIndex<TableDef, I>
+    : RangedIndex<TableDef, I>;
 
 /**
  * A type representing a collection of read-only indexes defined on a table.
@@ -67,15 +71,18 @@ export type ReadonlyIndexes<
 };
 
 /**
- * A type representing a read-only database index, which can be either unique or ranged.
+ * A type representing a read-only database index,
+ * which can be either unique, pointed, or ranged.
  * This type only exposes read-only operations.
  */
 export type ReadonlyIndex<
   TableDef extends UntypedTableDef,
   I extends UntypedIndex<keyof TableDef['columns'] & string>,
 > = I['unique'] extends true
   ? ReadonlyUniqueIndex<TableDef, I>
-  : ReadonlyRangedIndex<TableDef, I>;
+  : I['algorithm'] extends 'hash'
+    ? ReadonlyPointIndex<TableDef, I>
+    : ReadonlyRangedIndex<TableDef, I>;
 
 /**
  * A type representing a read-only unique index on a database table.
@@ -99,6 +106,29 @@ export interface UniqueIndex<
   update(colVal: Prettify<RowType<TableDef>>): Prettify<RowType<TableDef>>;
 }
 
+/**
+ * A type representing a read-only point index on a database table.
+ */
+export interface ReadonlyPointIndex<
+  TableDef extends UntypedTableDef,
+  I extends UntypedIndex<keyof TableDef['columns'] & string>,
+> {
+  filter(
+    point: IndexVal<TableDef, I>
+  ): IteratorObject<Prettify<RowType<TableDef>>, undefined>;
+}
+
+/**
+ * A type representing a point index on a database table.
+ * Point indexes allow for exact match queries on the indexed columns.
+ */
+export interface PointIndex<
+  TableDef extends UntypedTableDef,
+  I extends UntypedIndex<keyof TableDef['columns'] & string>,
+> extends ReadonlyPointIndex<TableDef, I> {
+  delete(point: IndexVal<TableDef, I>): number;
+}
+
 /**
  * A type representing a read-only ranged index on a database table.
  */
@@ -190,7 +220,7 @@ export type ColumnIndex<
     name: Name;
     unique: ColumnIsUnique<M>;
     columns: readonly [Name];
-    algorithm: 'btree' | 'direct';
+    algorithm: 'btree' | 'direct' | 'hash';
   } & (M extends {
     indexType: infer I extends NonNullable<IndexTypes>;
   }

crates/bindings-typescript/src/lib/table.ts

@@ -341,6 +341,9 @@ export function table<Row extends RowObj, const Opts extends TableOpts<Row>>(
         case 'btree':
           algorithm = RawIndexAlgorithm.BTree([id]);
           break;
+        case 'hash':
+          algorithm = RawIndexAlgorithm.Hash([id]);
+          break;
         case 'direct':
           algorithm = RawIndexAlgorithm.Direct(id);
           break;
@@ -398,6 +401,12 @@ export function table<Row extends RowObj, const Opts extends TableOpts<Row>>(
           value: indexOpts.columns.map(c => colIds.get(c)!),
         };
         break;
+      case 'hash':
+        algorithm = {
+          tag: 'Hash',
+          value: indexOpts.columns.map(c => colIds.get(c)!),
+        };
+        break;
       case 'direct':
         algorithm = { tag: 'Direct', value: colIds.get(indexOpts.column)! };
         break;

crates/bindings-typescript/src/lib/type_builders.ts

@@ -2070,7 +2070,7 @@ export class UuidBuilder
  * The type of index types that can be applied to a column.
  * `undefined` is the default
  */
-export type IndexTypes = 'btree' | 'direct' | undefined;
+export type IndexTypes = 'btree' | 'direct' | 'hash' | undefined;
 
 /**
  * Metadata describing column constraints and index type

crates/bindings-typescript/src/server/runtime.ts

@@ -18,6 +18,7 @@ import BinaryWriter, { ResizableBuffer } from '../lib/binary_writer';
 import {
   type Index,
   type IndexVal,
+  type PointIndex,
   type RangedIndex,
   type UniqueIndex,
 } from '../lib/indexes';
@@ -516,12 +517,15 @@ function makeTableView(
     const index_id = sys.index_id_from_name(indexDef.sourceName!);
 
     let column_ids: number[];
+    let isHashIndex = false;
     switch (indexDef.algorithm.tag) {
+      case 'Hash':
+        isHashIndex = true;
+        column_ids = indexDef.algorithm.value;
+        break;
       case 'BTree':
         column_ids = indexDef.algorithm.value;
         break;
-      case 'Hash':
-        throw new Error('impossible');
       case 'Direct':
         column_ids = [indexDef.algorithm.value];
         break;
@@ -649,7 +653,7 @@ function makeTableView(
       } as UniqueIndex<any, any>;
     } else if (serializeSinglePoint) {
       // numColumns == 1
-      index = {
+      const rawIndex = {
         filter: (range: any): IteratorObject<RowType<any>> => {
           const buf = LEAF_BUF;
           const point_len = serializeSinglePoint(buf, range);
@@ -669,7 +673,35 @@ function makeTableView(
             point_len
           );
         },
-      } as RangedIndex<any, any>;
+      };
+      if (isHashIndex) {
+        index = rawIndex as PointIndex<any, any>;
+      } else {
+        index = rawIndex as RangedIndex<any, any>;
+      }
+    } else if (isHashIndex) {
+      // numColumns != 1
+      index = {
+        filter: (range: any[]): IteratorObject<RowType<any>> => {
+          const buf = LEAF_BUF;
+          const point_len = serializePoint(buf, range);
+          const iter_id = sys.datastore_index_scan_point_bsatn(
+            index_id,
+            buf.buffer,
+            point_len
+          );
+          return tableIterator(iter_id, deserializeRow);
+        },
+        delete: (range: any[]): u32 => {
+          const buf = LEAF_BUF;
+          const point_len = serializePoint(buf, range);
+          return sys.datastore_delete_by_index_scan_point_bsatn(
+            index_id,
+            buf.buffer,
+            point_len
+          );
+        },
+      } as PointIndex<any, any>;
     } else {
       // numColumns != 1
       const serializeRange = (