fix: Index on JSON _geq and _leq null filter ops (#4415)

## Relevant issue(s)

Resolves #4398

## Description

Use index only for top-level `_leq: null` filter. Other cases like json
nested `_leq` or any `_geq` are ignore by index as there is no benefit
of using index there.

## Tasks

- [x] I made sure the code is well commented, particularly
hard-to-understand areas.
- [x] I made sure the repository-held documentation is changed
accordingly.
- [x] I made sure the pull request title adheres to the conventional
commit style (the subset used in the project can be found in
[tools/configs/chglog/config.yml](tools/configs/chglog/config.yml)).
- [x] I made sure to discuss its limitations such as threats to
validity, vulnerability to mistake and misuse, robustness to
invalidation of assumptions, resource requirements, ...

## How has this been tested?

Integration tests

Specify the platform(s) on which this was tested:
- MacOS

Author: islamaliev

cli/utils.go

@@ -184,10 +184,10 @@ func setContextRootDir(cmd *cobra.Command) error {
 func openKeyring(cmd *cobra.Command) (keyring.Keyring, error) {
 	cfg := mustGetContextConfig(cmd)
 	backend := cfg.Get("keyring.backend")
-	if backend == "system" {
+	if backend == keyring.KeyringBackendSystem {
 		return keyring.OpenSystemKeyring(cfg.GetString("keyring.namespace")), nil
 	}
-	if backend != "file" {
+	if backend != keyring.KeyringBackendFile {
 		log.Info("keyring defaulted to file backend")
 	}
 	path := cfg.GetString("keyring.path")

cli/wizard/callbacks.go

@@ -35,9 +35,9 @@ func callback_SetKeyringBackend(s step, ctx *WizardContext) error {
 		return NewErrModelTypeMismatch(s.ID(), "*modelMultipleChoice")
 	}
 
-	choice := "file"
+	choice := keyring.KeyringBackendFile
 	if mm.cursor == 1 {
-		choice = "system"
+		choice = keyring.KeyringBackendSystem
 	}
 
 	return setConfigValue(ctx, "keyring.backend", choice)

cli/wizard/unit_test.go

@@ -71,7 +71,7 @@ func Test_SetKeyringBackend(t *testing.T) {
 	if !ok {
 		t.Fatal("failed to type assert keyring.backend value")
 	}
-	if checkedValue != "file" {
+	if checkedValue != keyring.KeyringBackendFile {
 		t.Fatal("keyring.backend is not set to file")
 	}
 
@@ -84,7 +84,7 @@ func Test_SetKeyringBackend(t *testing.T) {
 	if !ok {
 		t.Fatal("failed to type assert keyring.backend value")
 	}
-	if checkedValue != "system" {
+	if checkedValue != keyring.KeyringBackendSystem {
 		t.Fatal("keyring.backend is not set to system")
 	}
 }

docs/data_format_changes/i4398-secondary-index-geq_leq-null.md

@@ -0,0 +1,3 @@
+# Secondary Index geq and leq on null
+
+Fix handling of `_geq` and `_leq` filters on null values with secondary indexes. Tests have been updated to include additional documents to improve coverage of edge cases with null values in JSON fields.

internal/db/fetcher/indexer_iterators.go

@@ -762,6 +762,15 @@ func (f *indexFetcher) determineFieldFilterConditions() ([]fieldFilterCond, erro
 						return true
 					}
 
+					// For _geq: null, every value is >= null, so the index provides no benefit -
+					// we need all documents anyway. Fall back to a full scan.
+					// For _leq: null on nested JSON paths, documents where the JSON field is entirely
+					// missing or null should also match. If path is specified though, the index
+					// has no efficient way of distinguishing between them. Fall back to scan.
+					if filterVal == nil && (op == opGe || (op == opLe && len(jsonPath) > 0)) {
+						return true
+					}
+
 					cond, err := makeFieldFilterCondition(op, jsonPath, indexedField, filterVal)
 
 					if err != nil {

keyring/keyring.go

@@ -10,11 +10,16 @@
 
 package keyring
 
+const (
+	KeyringBackendSystem = "system"
+	KeyringBackendFile   = "file"
+)
+
 // Keyring provides a simple set/get interface for a keyring service.
 type Keyring interface {
 	// Set stores the given key in the keystore under the given name.
 	//
-	// If a key with the given name already exists it will be overriden.
+	// If a key with the given name already exists it will be overridden.
 	Set(name string, key []byte) error
 	// Get returns the key with the given name from the keystore.
 	//

tests/integration/index/json_test.go

@@ -1717,3 +1717,257 @@ func TestJSONIndex_WithGreaterThanFilterOnTopLevelJSONField_ShouldUseIndex(t *te
 
 	testUtils.ExecuteTestCase(t, test)
 }
+
+func TestJSONIndex_WithGeqNullFilterOnTopLevelJSONField_ShouldNotUseIndex(t *testing.T) {
+	req := `query {
+		User(filter: {custom: {_geq: null}}) {
+			name
+		}
+	}`
+
+	test := testUtils.TestCase{
+		Actions: []any{
+			&action.AddSchema{
+				Schema: `
+					type User {
+						name: String
+						custom: JSON @index
+					}
+				`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "John",
+					"custom": 21
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "David",
+					"custom": {"age": 32}
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Bruno",
+					"custom": null
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Andy"
+				}`,
+			},
+			&action.Request{
+				Request: req,
+				Results: map[string]any{
+					"User": []map[string]any{
+						{"name": "John"},
+						{"name": "David"},
+						{"name": "Bruno"},
+						{"name": "Andy"},
+					},
+				},
+				NonOrderedResults: true,
+			},
+			&action.Request{
+				Request:  makeExplainQuery(req),
+				Asserter: testUtils.NewExplainAsserter().WithIndexFetches(0),
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}
+
+func TestJSONIndex_WithGeqNullFilterOnNestedJSONPath_ShouldNotUseIndex(t *testing.T) {
+	req := `query {
+		User(filter: {custom: {age: {_geq: null}}}) {
+			name
+		}
+	}`
+
+	test := testUtils.TestCase{
+		Actions: []any{
+			&action.AddSchema{
+				Schema: `
+					type User {
+						name: String
+						custom: JSON @index
+					}
+				`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "John",
+					"custom": {"age": 21}
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "David",
+					"custom": {"age": null}
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Bruno"
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Andy",
+					"custom": {"height": 180}
+				}`,
+			},
+			&action.Request{
+				Request: req,
+				Results: map[string]any{
+					"User": []map[string]any{
+						{"name": "John"},
+						{"name": "David"},
+						{"name": "Bruno"},
+						{"name": "Andy"},
+					},
+				},
+				NonOrderedResults: true,
+			},
+			&action.Request{
+				Request:  makeExplainQuery(req),
+				Asserter: testUtils.NewExplainAsserter().WithIndexFetches(0),
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}
+
+func TestJSONIndex_WithLeqNullFilterOnTopLevelJSONField_ShouldUseIndex(t *testing.T) {
+	req := `query {
+		User(filter: {custom: {_leq: null}}) {
+			name
+		}
+	}`
+
+	test := testUtils.TestCase{
+		Actions: []any{
+			&action.AddSchema{
+				Schema: `
+					type User {
+						name: String
+						custom: JSON @index
+					}
+				`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "John",
+					"custom": 21
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "David",
+					"custom": {"age": 32}
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Shahzad",
+					"custom": {"age": null}
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Bruno",
+					"custom": null
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Andy"
+				}`,
+			},
+			&action.Request{
+				Request: req,
+				Results: map[string]any{
+					"User": []map[string]any{
+						{"name": "Bruno"},
+						{"name": "Andy"},
+					},
+				},
+				NonOrderedResults: true,
+			},
+			&action.Request{
+				Request:  makeExplainQuery(req),
+				Asserter: testUtils.NewExplainAsserter().WithIndexFetches(2),
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}
+
+func TestJSONIndex_WithLeqNullFilterOnNestedJSONPath_ShouldNotUseIndex(t *testing.T) {
+	// _leq: null on nested paths matches documents where the path evaluates to null
+	// This includes: explicit null at the path, missing path, missing JSON field entirely
+	// The index can't efficiently handle all these cases, so it falls back to full scan
+	req := `query {
+		User(filter: {custom: {age: {_leq: null}}}) {
+			name
+		}
+	}`
+
+	test := testUtils.TestCase{
+		Actions: []any{
+			&action.AddSchema{
+				Schema: `
+					type User {
+						name: String
+						custom: JSON @index
+					}
+				`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "John",
+					"custom": {"age": 21}
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "David",
+					"custom": {"age": null}
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Bruno"
+				}`,
+			},
+			&action.CreateDoc{
+				Doc: `{
+					"name": "Andy",
+					"custom": {"height": 180}
+				}`,
+			},
+			&action.Request{
+				Request: req,
+				Results: map[string]any{
+					"User": []map[string]any{
+						{"name": "David"},
+						{"name": "Bruno"},
+						{"name": "Andy"},
+					},
+				},
+				NonOrderedResults: true,
+			},
+			&action.Request{
+				Request:  makeExplainQuery(req),
+				Asserter: testUtils.NewExplainAsserter().WithIndexFetches(0),
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, test)
+}