Support descending queries

Author: schmidt-sebastian

packages/firestore/src/core/target.ts

@@ -20,7 +20,9 @@ import { DocumentKey } from '../model/document_key';
 import {
   FieldIndex,
   fieldIndexGetArraySegment,
-  fieldIndexGetDirectionalSegments
+  fieldIndexGetDirectionalSegments,
+  IndexKind,
+  IndexSegment
 } from '../model/field_index';
 import { FieldPath, ResourcePath } from '../model/path';
 import {
@@ -304,70 +306,21 @@ export function targetGetLowerBound(
   // For each segment, retrieve a lower bound if there is a suitable filter or
   // startAt.
   for (const segment of fieldIndexGetDirectionalSegments(fieldIndex)) {
-    let segmentValue: ProtoValue | undefined = undefined;
-    let segmentInclusive = true;
+    const segmentBound =
+      segment.kind === IndexKind.ASCENDING
+        ? targetGetAscendingBound(target, segment, target.startAt)
+        : targetGetDescendingBound(target, segment, target.startAt);
 
-    // Process all filters to find a value for the current field segment
-    for (const fieldFilter of targetGetFieldFiltersForPath(
-      target,
-      segment.fieldPath
-    )) {
-      let filterValue: ProtoValue | undefined = undefined;
-      let filterInclusive = true;
-
-      switch (fieldFilter.op) {
-        case Operator.LESS_THAN:
-        case Operator.LESS_THAN_OR_EQUAL:
-          filterValue = valuesGetLowerBound(fieldFilter.value);
-          break;
-        case Operator.EQUAL:
-        case Operator.IN:
-        case Operator.GREATER_THAN_OR_EQUAL:
-          filterValue = fieldFilter.value;
-          break;
-        case Operator.GREATER_THAN:
-          filterValue = fieldFilter.value;
-          filterInclusive = false;
-          break;
-        case Operator.NOT_EQUAL:
-        case Operator.NOT_IN:
-          filterValue = MIN_VALUE;
-          break;
-        default:
-        // Remaining filters cannot be used as lower bounds.
-      }
-
-      if (valuesMax(segmentValue, filterValue) === filterValue) {
-        segmentValue = filterValue;
-        segmentInclusive = filterInclusive;
-      }
-    }
-
-    // If there is a startAt bound, compare the values against the existing
-    // boundary to see if we can narrow the scope.
-    if (target.startAt !== null) {
-      for (let i = 0; i < target.orderBy.length; ++i) {
-        const orderBy = target.orderBy[i];
-        if (orderBy.field.isEqual(segment.fieldPath)) {
-          const cursorValue = target.startAt.position[i];
-          if (valuesMax(segmentValue, cursorValue) === cursorValue) {
-            segmentValue = cursorValue;
-            segmentInclusive = target.startAt.inclusive;
-          }
-          break;
-        }
-      }
-    }
-
-    if (segmentValue === undefined) {
+    if (!segmentBound.value) {
       // No lower bound exists
       return null;
     }
-    values.push(segmentValue);
-    inclusive &&= segmentInclusive;
+    values.push(segmentBound.value);
+    inclusive &&= segmentBound.inclusive;
   }
   return new Bound(values, inclusive);
 }
+
 /**
  * Returns an upper bound of field values that can be used as an ending point
  * when scanning the index defined by `fieldIndex`. Returns `null` if no
@@ -383,71 +336,147 @@ export function targetGetUpperBound(
   // For each segment, retrieve an upper bound if there is a suitable filter or
   // endAt.
   for (const segment of fieldIndexGetDirectionalSegments(fieldIndex)) {
-    let segmentValue: ProtoValue | undefined = undefined;
-    let segmentInclusive = true;
+    const segmentBound =
+      segment.kind === IndexKind.ASCENDING
+        ? targetGetDescendingBound(target, segment, target.endAt)
+        : targetGetAscendingBound(target, segment, target.endAt);
 
-    // Process all filters to find a value for the current field segment
-    for (const fieldFilter of targetGetFieldFiltersForPath(
-      target,
-      segment.fieldPath
-    )) {
-      let filterValue: ProtoValue | undefined = undefined;
-      let filterInclusive = true;
+    if (!segmentBound.value) {
+      // No upper bound exists
+      return null;
+    }
+    values.push(segmentBound.value);
+    inclusive &&= segmentBound.inclusive;
+  }
 
-      switch (fieldFilter.op) {
-        case Operator.GREATER_THAN_OR_EQUAL:
-        case Operator.GREATER_THAN:
-          filterValue = valuesGetUpperBound(fieldFilter.value);
-          filterInclusive = false;
-          break;
-        case Operator.EQUAL:
-        case Operator.IN:
-        case Operator.LESS_THAN_OR_EQUAL:
-          filterValue = fieldFilter.value;
-          break;
-        case Operator.LESS_THAN:
-          filterValue = fieldFilter.value;
-          filterInclusive = false;
-          break;
-        case Operator.NOT_EQUAL:
-        case Operator.NOT_IN:
-          filterValue = MAX_VALUE;
-          break;
-        default:
-        // Remaining filters cannot be used as upper bounds.
-      }
+  return new Bound(values, inclusive);
+}
 
-      if (valuesMin(segmentValue, filterValue) === filterValue) {
-        segmentValue = filterValue;
-        segmentInclusive = filterInclusive;
-      }
+function targetGetAscendingBound(
+  target: Target,
+  segment: IndexSegment,
+  bound: Bound | null
+): { value: ProtoValue | undefined; inclusive: boolean } {
+  let value: ProtoValue | undefined = undefined;
+  let inclusive = true;
+
+  // Process all filters to find a value for the current field segment
+  for (const fieldFilter of targetGetFieldFiltersForPath(
+    target,
+    segment.fieldPath
+  )) {
+    let filterValue: ProtoValue | undefined = undefined;
+    let filterInclusive = true;
+
+    switch (fieldFilter.op) {
+      case Operator.LESS_THAN:
+      case Operator.LESS_THAN_OR_EQUAL:
+        filterValue = valuesGetLowerBound(fieldFilter.value);
+        break;
+      case Operator.EQUAL:
+      case Operator.IN:
+      case Operator.GREATER_THAN_OR_EQUAL:
+        filterValue = fieldFilter.value;
+        break;
+      case Operator.GREATER_THAN:
+        filterValue = fieldFilter.value;
+        filterInclusive = false;
+        break;
+      case Operator.NOT_EQUAL:
+      case Operator.NOT_IN:
+        filterValue = MIN_VALUE;
+        break;
+      default:
+      // Remaining filters cannot be used as lower bounds.
     }
 
-    // If there is a endAt bound, compare the values against the existing
-    // boundary to see if we can narrow the scope.
-    if (target.endAt !== null) {
-      for (let i = 0; i < target.orderBy.length; ++i) {
-        const orderBy = target.orderBy[i];
-        if (orderBy.field.isEqual(segment.fieldPath)) {
-          const cursorValue = target.endAt.position[i];
-          if (valuesMin(segmentValue, cursorValue) === cursorValue) {
-            segmentValue = cursorValue;
-            segmentInclusive = target.endAt.inclusive;
-          }
-          break;
+    if (valuesMax(value, filterValue) === filterValue) {
+      value = filterValue;
+      inclusive = filterInclusive;
+    }
+  }
+
+  // If there is an additional bound, compare the values against the existing
+  // range to see if we can narrow the scope.
+  if (bound !== null) {
+    for (let i = 0; i < target.orderBy.length; ++i) {
+      const orderBy = target.orderBy[i];
+      if (orderBy.field.isEqual(segment.fieldPath)) {
+        const cursorValue = bound.position[i];
+        if (valuesMax(value, cursorValue) === cursorValue) {
+          value = cursorValue;
+          inclusive = bound.inclusive;
         }
+        break;
       }
     }
+  }
 
-    if (segmentValue === undefined) {
-      // No upper bound exists
-      return null;
+  return { value, inclusive };
+}
+
+function targetGetDescendingBound(
+  target: Target,
+  segment: IndexSegment,
+  bound: Bound | null
+): { value: ProtoValue | undefined; inclusive: boolean } {
+  let value: ProtoValue | undefined = undefined;
+  let inclusive = true;
+
+  // Process all filters to find a value for the current field segment
+  for (const fieldFilter of targetGetFieldFiltersForPath(
+    target,
+    segment.fieldPath
+  )) {
+    let filterValue: ProtoValue | undefined = undefined;
+    let filterInclusive = true;
+
+    switch (fieldFilter.op) {
+      case Operator.GREATER_THAN_OR_EQUAL:
+      case Operator.GREATER_THAN:
+        filterValue = valuesGetUpperBound(fieldFilter.value);
+        filterInclusive = false;
+        break;
+      case Operator.EQUAL:
+      case Operator.IN:
+      case Operator.LESS_THAN_OR_EQUAL:
+        filterValue = fieldFilter.value;
+        break;
+      case Operator.LESS_THAN:
+        filterValue = fieldFilter.value;
+        filterInclusive = false;
+        break;
+      case Operator.NOT_EQUAL:
+      case Operator.NOT_IN:
+        filterValue = MAX_VALUE;
+        break;
+      default:
+      // Remaining filters cannot be used as upper bounds.
+    }
+
+    if (valuesMin(value, filterValue) === filterValue) {
+      value = filterValue;
+      inclusive = filterInclusive;
     }
-    values.push(segmentValue);
-    inclusive &&= segmentInclusive;
   }
 
-  return new Bound(values, inclusive);
+  // If there is an additional bound, compare the values against the existing
+  // range to see if we can narrow the scope.
+  if (bound !== null) {
+    for (let i = 0; i < target.orderBy.length; ++i) {
+      const orderBy = target.orderBy[i];
+      if (orderBy.field.isEqual(segment.fieldPath)) {
+        const cursorValue = bound.position[i];
+        if (valuesMin(value, cursorValue) === cursorValue) {
+          value = cursorValue;
+          inclusive = bound.inclusive;
+        }
+        break;
+      }
+    }
+  }
+
+  return { value, inclusive };
 }
 
 export abstract class Filter {

packages/firestore/src/index/index_entry.ts

@@ -16,6 +16,7 @@
  */
 
 import { DocumentKey } from '../model/document_key';
+import { primitiveComparator } from '../util/misc';
 
 /** Represents an index entry saved by the SDK in persisted storage. */
 export class IndexEntry {
@@ -73,7 +74,7 @@ export function indexEntryComparator(
     return cmp;
   }
 
-  return DocumentKey.comparator(left.documentKey, right.documentKey);
+  return primitiveComparator(left.documentKey, right.documentKey);
 }
 
 export function compareByteArrays(left: Uint8Array, right: Uint8Array): number {

packages/firestore/src/local/index_manager.ts

@@ -16,7 +16,8 @@
  */
 
 import { Target } from '../core/target';
-import { DocumentKeySet, DocumentMap } from '../model/collections';
+import { DocumentMap } from '../model/collections';
+import { DocumentKey } from '../model/document_key';
 import { FieldIndex, IndexOffset } from '../model/field_index';
 import { ResourcePath } from '../model/path';
 
@@ -108,7 +109,7 @@ export interface IndexManager {
   getDocumentsMatchingTarget(
     transaction: PersistenceTransaction,
     target: Target
-  ): PersistencePromise<DocumentKeySet | null>;
+  ): PersistencePromise<DocumentKey[] | null>;
 
   /**
    * Returns the next collection group to update. Returns `null` if no group