perf(zql): probe the last view entry before binary-searching

packages/zql/src/ivm/data.ts

@@ -89,11 +89,24 @@ export function normalizeUndefined(v: Value): NormalizedValue {
 export type Comparator = (r1: Row, r2: Row) => number;
 
 export function makeComparator(order: Ordering, reverse?: boolean): Comparator {
+  // A single ascending field is the common shape -- it is what every source
+  // ordered by a single-column primary key gets -- and specializing it drops
+  // the loop, the direction test and the reverse test from the hottest
+  // function in hydration.
+  if (order.length === 1 && order[0][1] === 'asc' && !reverse) {
+    const field = order[0][0];
+    return (a, b) => compareValues(a[field], b[field]);
+  }
+
+  const length = order.length;
   return (a, b) => {
-    // Skip destructuring here since it is hot code.
-    for (const ord of order) {
-      const field = ord[0];
-      const comp = compareValues(a[field], b[field]);
+    // Skip destructuring here since it is hot code. An indexed loop rather
+    // than `for...of` for the same reason: Hermes allocates an iterator and
+    // calls `next()` per element, which costs more than the comparison for an
+    // ordering this short.
+    for (let i = 0; i < length; i++) {
+      const ord = order[i];
+      const comp = compareValues(a[ord[0]], b[ord[0]]);
       if (comp !== 0) {
         const result = ord[1] === 'asc' ? comp : -comp;
         return reverse ? -result : result;

packages/zql/src/ivm/view-apply-change.ts

@@ -768,11 +768,31 @@ function binarySearch(
   target: Row,
   comparator: Comparator,
 ): number {
-  let low = 0;
   let high = view.length - 1;
+  if (high < 0) {
+    return ~0;
+  }
+
+  // Probe the last entry before searching. Hydration feeds the view rows in
+  // the query's sort order, so every insert belongs at the end and the plain
+  // search spends log2(n) comparisons to rediscover that -- about eleven per
+  // row for a view of a couple of thousand. Row comparison is the single
+  // largest cost in hydration on Hermes, so collapsing those eleven to one is
+  // worth the one extra comparison this costs when the row does land inside
+  // the view, which is a single push rather than a bulk load.
+  // MetaEntry has all Row props; comparator only reads string keys
+  const last = comparator(view[high] as Row, target);
+  if (last < 0) {
+    return ~(high + 1);
+  }
+  if (last === 0) {
+    return high;
+  }
+
+  let low = 0;
+  high -= 1;
   while (low <= high) {
     const mid = (low + high) >>> 1;
-    // MetaEntry has all Row props; comparator only reads string keys
     const comparison = comparator(view[mid] as Row, target);
     if (comparison < 0) {
       low = mid + 1;