fix: Handle limit and offset in sub groups (#440)

db/tests/query/simple/with_group_limit_offset_test.go

@@ -0,0 +1,99 @@
+// Copyright 2022 Democratized Data Foundation
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package simple
+
+import (
+	"testing"
+
+	testUtils "github.com/sourcenetwork/defradb/db/tests"
+)
+
+func TestQuerySimpleWithGroupByNumberWithGroupLimitAndOffset(t *testing.T) {
+	test := testUtils.QueryTestCase{
+		Description: "Simple query with group by number, no children, rendered, limited and offset group",
+		Query: `query {
+					users(groupBy: [Age]) {
+						Age
+						_group(limit: 1, offset: 1) {
+							Name
+						}
+					}
+				}`,
+		Docs: map[int][]string{
+			0: {
+				(`{
+				"Name": "John",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Bob",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Alice",
+				"Age": 19
+			}`)},
+		},
+		Results: []map[string]interface{}{
+			{
+				"Age": uint64(32),
+				"_group": []map[string]interface{}{
+					{
+						"Name": "John",
+					},
+				},
+			},
+			{
+				"Age":    uint64(19),
+				"_group": []map[string]interface{}{},
+			},
+		},
+	}
+
+	executeTestCase(t, test)
+}
+
+func TestQuerySimpleWithGroupByNumberWithLimitAndOffsetAndWithGroupLimitAndOffset(t *testing.T) {
+	test := testUtils.QueryTestCase{
+		Description: "Simple query with group by number with limit and offset, no children, rendered, limited and offset group",
+		Query: `query {
+					users(groupBy: [Age], limit: 1, offset: 1) {
+						Age
+						_group(limit: 1, offset: 1) {
+							Name
+						}
+					}
+				}`,
+		Docs: map[int][]string{
+			0: {
+				(`{
+				"Name": "John",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Bob",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Alice",
+				"Age": 19
+			}`)},
+		},
+		Results: []map[string]interface{}{
+			{
+				"Age":    uint64(19),
+				"_group": []map[string]interface{}{},
+			},
+		},
+	}
+
+	executeTestCase(t, test)
+}

db/tests/query/simple/with_group_limit_test.go

@@ -0,0 +1,228 @@
+// Copyright 2022 Democratized Data Foundation
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package simple
+
+import (
+	"testing"
+
+	testUtils "github.com/sourcenetwork/defradb/db/tests"
+)
+
+func TestQuerySimpleWithGroupByNumberWithGroupLimit(t *testing.T) {
+	test := testUtils.QueryTestCase{
+		Description: "Simple query with group by number, no children, rendered, limited group",
+		Query: `query {
+					users(groupBy: [Age]) {
+						Age
+						_group(limit: 1) {
+							Name
+						}
+					}
+				}`,
+		Docs: map[int][]string{
+			0: {
+				(`{
+				"Name": "John",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Bob",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Alice",
+				"Age": 19
+			}`)},
+		},
+		Results: []map[string]interface{}{
+			{
+				"Age": uint64(32),
+				"_group": []map[string]interface{}{
+					{
+						"Name": "Bob",
+					},
+				},
+			},
+			{
+				"Age": uint64(19),
+				"_group": []map[string]interface{}{
+					{
+						"Name": "Alice",
+					},
+				},
+			},
+		},
+	}
+
+	executeTestCase(t, test)
+}
+
+func TestQuerySimpleWithGroupByNumberWithMultipleGroupsWithDifferentLimits(t *testing.T) {
+	test := testUtils.QueryTestCase{
+		Description: "Simple query with group by number, no children, multiple rendered, limited groups",
+		Query: `query {
+					users(groupBy: [Age]) {
+						Age
+						G1: _group(limit: 1) {
+							Name
+						}
+						G2: _group(limit: 2) {
+							Name
+						}
+					}
+				}`,
+		Docs: map[int][]string{
+			0: {
+				(`{
+				"Name": "John",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Bob",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Alice",
+				"Age": 19
+			}`)},
+		},
+		Results: []map[string]interface{}{
+			{
+				"Age": uint64(32),
+				"G1": []map[string]interface{}{
+					{
+						"Name": "Bob",
+					},
+				},
+				"G2": []map[string]interface{}{
+					{
+						"Name": "Bob",
+					},
+					{
+						"Name": "John",
+					},
+				},
+			},
+			{
+				"Age": uint64(19),
+				"G1": []map[string]interface{}{
+					{
+						"Name": "Alice",
+					},
+				},
+				"G2": []map[string]interface{}{
+					{
+						"Name": "Alice",
+					},
+				},
+			},
+		},
+	}
+
+	executeTestCase(t, test)
+}
+
+func TestQuerySimpleWithGroupByNumberWithLimitAndGroupWithHigherLimit(t *testing.T) {
+	test := testUtils.QueryTestCase{
+		Description: "Simple query with group by number and limit, no children, rendered, limited group",
+		Query: `query {
+					users(groupBy: [Age], limit: 1) {
+						Age
+						_group(limit: 2) {
+							Name
+						}
+					}
+				}`,
+		Docs: map[int][]string{
+			0: {
+				(`{
+				"Name": "John",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Bob",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Alice",
+				"Age": 19
+			}`)},
+		},
+		Results: []map[string]interface{}{
+			{
+				"Age": uint64(32),
+				"_group": []map[string]interface{}{
+					{
+						"Name": "Bob",
+					},
+					{
+						"Name": "John",
+					},
+				},
+			},
+		},
+	}
+
+	executeTestCase(t, test)
+}
+
+func TestQuerySimpleWithGroupByNumberWithLimitAndGroupWithLowerLimit(t *testing.T) {
+	test := testUtils.QueryTestCase{
+		Description: "Simple query with group by number and limit, no children, rendered, limited group",
+		Query: `query {
+					users(groupBy: [Age], limit: 2) {
+						Age
+						_group(limit: 1) {
+							Name
+						}
+					}
+				}`,
+		Docs: map[int][]string{
+			0: {
+				(`{
+				"Name": "John",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Bob",
+				"Age": 32
+			}`),
+				(`{
+				"Name": "Alice",
+				"Age": 19
+			}`),
+				(`{
+				"Name": "Alice",
+				"Age": 42
+			}`)},
+		},
+		Results: []map[string]interface{}{
+			{
+				"Age": uint64(32),
+				"_group": []map[string]interface{}{
+					{
+						"Name": "Bob",
+					},
+				},
+			},
+			{
+				"Age": uint64(42),
+				"_group": []map[string]interface{}{
+					{
+						"Name": "Alice",
+					},
+				},
+			},
+		},
+	}
+
+	executeTestCase(t, test)
+}

query/graphql/planner/group.go

@@ -121,6 +121,30 @@ func (n *groupNode) Next() (bool, error) {
 		}
 
 		n.values = values.values
+
+		for _, group := range n.values {
+			for _, childSelect := range n.childSelects {
+				subSelect, hasSubSelect := group[childSelect.Name]
+				if !hasSubSelect {
+					continue
+				}
+
+				childDocs := subSelect.([]map[string]interface{})
+				if childSelect.Limit != nil {
+					l := int64(len(childDocs))
+
+					// We must hide all child documents before the offset
+					for i := int64(0); i < childSelect.Limit.Offset && i < l; i++ {
+						childDocs[i][parser.HiddenFieldName] = struct{}{}
+					}
+
+					// We must hide all child documents after the offset plus limit
+					for i := childSelect.Limit.Limit + childSelect.Limit.Offset; i < l; i++ {
+						childDocs[i][parser.HiddenFieldName] = struct{}{}
+					}
+				}
+			}
+		}
 	}
 
 	if n.currentIndex < len(n.values) {

query/graphql/planner/planner.go

@@ -339,6 +339,13 @@ func (p *Planner) expandLimitPlan(plan *selectTopNode, parentPlan *selectTopNode
 			return nil
 		}
 
+		// Limits get more complicated with groups and have to be handled internally, so we ensure
+		// any limit plan is disabled here
+		if parentPlan != nil && parentPlan.group != nil && len(parentPlan.group.childSelects) != 0 {
+			plan.limit = nil
+			return nil
+		}
+
 		// if this is a child node, and the parent select has an aggregate then we need to
 		// replace the hard limit with a render limit to allow the full set of child records
 		// to be aggregated