diff --git a/README.md b/README.md
index f0e4495f7..e986f0223 100644
--- a/README.md
+++ b/README.md
@@ -473,9 +473,22 @@ store.select(selectUser, 1).subsribe(user => {
 });
 ```
 
+### Gathering information of a selector
+
+Besides the `release` function every selector provides information about itself.
+
+* `ngrxEntityRelationship` - name of its function: `rootEntity`, `rootEntities`, `relatedEntity`, `childEntity` and `childrenEntities`.
+* `collectionSelector` - a function that returns a collection of its entity.
+* `idSelector` - a function that returns the id of the related entity.
+* `relationships` - an array of passed relationships.
+
+In case of relationship functions there are two more keys
+* `keyId` - a name of the keyId field.
+* `keyValue` - a name of the keyValue field.
+
 ## Additional examples
 
-Of course we can select as many relationships as we want until we have a field with a related id.
+Of course, we can select as many relationships as we want until we have a field with a related id.
 Check how `childrenEntities` works. It gathers entities based on a parent field.
 
 ```typescript
diff --git a/src/childEntity.ts b/src/childEntity.ts
index ddce05b5c..40fb8ec81 100644
--- a/src/childEntity.ts
+++ b/src/childEntity.ts
@@ -38,7 +38,7 @@ export function childEntity<
     let relationships: Array<HANDLER_RELATED_ENTITY<STORE, RELATED_ENTITY>> = [...arguments];
     relationships = relationships.slice(3);
 
-    const {collection: funcSelector, id: idSelector} = normalizeSelector(featureSelector);
+    const {collection: collectionSelector, id: idSelector} = normalizeSelector(featureSelector);
 
     const callback = (
         cacheLevel: string,
@@ -47,7 +47,7 @@ export function childEntity<
         source: PARENT_ENTITY,
         idParentSelector: ID_SELECTOR<PARENT_ENTITY>,
     ) => {
-        const featureState = funcSelector(state);
+        const featureState = collectionSelector(state);
         const parentId = idParentSelector(source);
 
         let cacheDataLevel = cache.get(cacheLevel);
@@ -75,7 +75,7 @@ export function childEntity<
             }
             idChecks = new Map();
             const idChecksEntities = new Map();
-            idChecks.set(funcSelector, idChecksEntities);
+            idChecks.set(collectionSelector, idChecksEntities);
             idChecksEntities.set(null, featureState.entities);
             cacheDataLevel.set(`!${parentId}`, [idChecks, id]);
         }
@@ -97,7 +97,7 @@ export function childEntity<
         value = undefined;
         checks = new Map();
         const checksEntities = new Map();
-        checks.set(funcSelector, checksEntities);
+        checks.set(collectionSelector, checksEntities);
         checksEntities.set(null, featureState.entities);
         checksEntities.set(id, featureState.entities[id]);
 
@@ -118,7 +118,11 @@ export function childEntity<
         return cacheHash;
     };
     callback.ngrxEntityRelationship = 'childEntity';
+    callback.collectionSelector = collectionSelector;
     callback.idSelector = idSelector;
+    callback.relationships = relationships;
+    callback.keyId = keyId;
+    callback.keyValue = keyValue;
     callback.release = () => {
         for (const relationship of relationships) {
             relationship.release();
diff --git a/src/childrenEntities.ts b/src/childrenEntities.ts
index e42bc4074..f48bfc385 100644
--- a/src/childrenEntities.ts
+++ b/src/childrenEntities.ts
@@ -38,7 +38,7 @@ export function childrenEntities<
     let relationships: Array<HANDLER_RELATED_ENTITY<STORE, RELATED_ENTITY>> = [...arguments];
     relationships = relationships.slice(3);
 
-    const {collection: funcSelector, id: idSelector} = normalizeSelector(featureSelector);
+    const {collection: collectionSelector, id: idSelector} = normalizeSelector(featureSelector);
     const emptyResult: Map<UNKNOWN, UNKNOWN> = new Map();
 
     const callback = (
@@ -48,7 +48,7 @@ export function childrenEntities<
         source: PARENT_ENTITY,
         idParentSelector: ID_SELECTOR<PARENT_ENTITY>,
     ) => {
-        const featureState = funcSelector(state);
+        const featureState = collectionSelector(state);
         const parentId = idParentSelector(source);
 
         let cacheDataLevel = cache.get(cacheLevel);
@@ -78,7 +78,7 @@ export function childrenEntities<
             }
             idsChecks = new Map();
             const idsChecksEntities = new Map();
-            idsChecks.set(funcSelector, idsChecksEntities);
+            idsChecks.set(collectionSelector, idsChecksEntities);
             idsChecksEntities.set(null, featureState.entities);
             cacheDataLevel.set(`!${parentId}`, [idsChecks, ids]);
         }
@@ -105,7 +105,7 @@ export function childrenEntities<
         value = [];
         checks = new Map();
         const checksEntities = new Map();
-        checks.set(funcSelector, checksEntities);
+        checks.set(collectionSelector, checksEntities);
         checksEntities.set(null, featureState.entities);
         for (const id of ids) {
             checksEntities.set(id, featureState.entities[id]);
@@ -125,7 +125,7 @@ export function childrenEntities<
             entityValue = {...featureState.entities[id]} as RELATED_ENTITY;
             entityChecks = new Map();
             const entityChecksEntities = new Map();
-            entityChecks.set(funcSelector, entityChecksEntities);
+            entityChecks.set(collectionSelector, entityChecksEntities);
             entityChecksEntities.set(null, featureState.entities);
             entityChecksEntities.set(id, featureState.entities[id]);
 
@@ -147,7 +147,11 @@ export function childrenEntities<
         return cacheHash;
     };
     callback.ngrxEntityRelationship = 'childrenEntities';
+    callback.collectionSelector = collectionSelector;
     callback.idSelector = idSelector;
+    callback.relationships = relationships;
+    callback.keyId = keyId;
+    callback.keyValue = keyValue;
     callback.release = () => {
         emptyResult.clear();
         for (const relationship of relationships) {
diff --git a/src/relatedEntity.ts b/src/relatedEntity.ts
index 54f46b406..9272623dd 100644
--- a/src/relatedEntity.ts
+++ b/src/relatedEntity.ts
@@ -41,7 +41,7 @@ export function relatedEntity<
     let relationships: Array<HANDLER_RELATED_ENTITY<STORE, RELATED_ENTITY>> = [...arguments];
     relationships = relationships.slice(3);
 
-    const {collection: funcSelector, id: idSelector} = normalizeSelector(featureSelector);
+    const {collection: collectionSelector, id: idSelector} = normalizeSelector(featureSelector);
     const emptyResult: Map<UNKNOWN, UNKNOWN> = new Map();
 
     const callback = (cacheLevel: string, state: STORE, cache: CACHE<STORE>, source: PARENT_ENTITY) => {
@@ -51,7 +51,7 @@ export function relatedEntity<
             return;
         }
 
-        const featureState = funcSelector(state);
+        const featureState = collectionSelector(state);
 
         let cacheDataLevel = cache.get(cacheLevel);
         if (!cacheDataLevel) {
@@ -95,7 +95,7 @@ export function relatedEntity<
         value = undefined;
         checks = new Map();
         const checkIds = new Map();
-        checks.set(funcSelector, checkIds);
+        checks.set(collectionSelector, checkIds);
         checkIds.set(null, featureState.entities);
         for (const id of ids) {
             checkIds.set(id, featureState.entities[id]);
@@ -119,7 +119,7 @@ export function relatedEntity<
             entityValue = {...featureState.entities[id]} as RELATED_ENTITY;
             entityChecks = new Map();
             const entityCheckIds = new Map();
-            entityChecks.set(funcSelector, entityCheckIds);
+            entityChecks.set(collectionSelector, entityCheckIds);
             entityCheckIds.set(null, featureState.entities);
             entityCheckIds.set(id, featureState.entities[id]);
 
@@ -142,7 +142,11 @@ export function relatedEntity<
         return cacheHash;
     };
     callback.ngrxEntityRelationship = 'relatedEntity';
+    callback.collectionSelector = collectionSelector;
     callback.idSelector = idSelector;
+    callback.relationships = relationships;
+    callback.keyId = keyId;
+    callback.keyValue = keyValue;
     callback.release = () => {
         emptyResult.clear();
         for (const relationship of relationships) {
diff --git a/src/rootEntities.ts b/src/rootEntities.ts
index 235d7d568..f2746cd3e 100644
--- a/src/rootEntities.ts
+++ b/src/rootEntities.ts
@@ -53,7 +53,9 @@ export function rootEntities<STORE, ENTITY, TRANSFORMED>(
         return value;
     };
     callback.ngrxEntityRelationship = 'rootEntities';
+    callback.collectionSelector = rootSelector.collectionSelector;
     callback.idSelector = rootSelector.idSelector;
+    callback.relationships = rootSelector.relationships;
     callback.release = () => {
         cacheMap.clear();
         rootSelector.release();
diff --git a/src/rootEntity.ts b/src/rootEntity.ts
index dd24a9b8f..31b6000ea 100644
--- a/src/rootEntity.ts
+++ b/src/rootEntity.ts
@@ -33,7 +33,7 @@ export function rootEntity<STORE, ENTITY, TRANSFORMED>(
         transformer = deside;
         relationships = relationships.slice(1);
     }
-    const {collection: funcSelector, id: idSelector} = normalizeSelector(featureSelector);
+    const {collection: collectionSelector, id: idSelector} = normalizeSelector(featureSelector);
 
     const cacheLevel = '0';
     const cache: CACHE<STORE> = new Map();
@@ -43,7 +43,7 @@ export function rootEntity<STORE, ENTITY, TRANSFORMED>(
             return;
         }
 
-        const featureState = funcSelector(state);
+        const featureState = collectionSelector(state);
         let cacheDataLevel = cache.get(cacheLevel);
         if (!cacheDataLevel) {
             cacheDataLevel = new Map();
@@ -66,7 +66,7 @@ export function rootEntity<STORE, ENTITY, TRANSFORMED>(
         value = undefined;
         checks = new Map();
         const checkIds = new Map();
-        checks.set(funcSelector, checkIds);
+        checks.set(collectionSelector, checkIds);
         checkIds.set(null, featureState.entities);
         checkIds.set(id, featureState.entities[id]);
 
@@ -94,7 +94,9 @@ export function rootEntity<STORE, ENTITY, TRANSFORMED>(
         return value;
     };
     callback.ngrxEntityRelationship = 'rootEntity';
+    callback.collectionSelector = collectionSelector;
     callback.idSelector = idSelector;
+    callback.relationships = relationships;
     callback.release = () => {
         cache.clear();
         for (const relationship of relationships) {
diff --git a/src/types.ts b/src/types.ts
index d0ce9c1fa..0a3953537 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -41,17 +41,21 @@ export type CACHE_CHECKS = Map<ID_TYPES | null, UNKNOWN>;
 export type CACHE_CHECKS_SET<S> = Map<STORE_SELECTOR<S, ENTITY_STATE<UNKNOWN>>, CACHE_CHECKS>;
 export type CACHE<S> = Map<string, Map<string | null, [CACHE_CHECKS_SET<S>, UNKNOWN]>>;
 
-export type HANDLER_ROOT_ENTITY<S, F, T, I> = {
+export type HANDLER_ROOT_ENTITY<S, E, T, I> = {
     (state: S, id: I): undefined | T;
     ngrxEntityRelationship: string;
-    idSelector: ID_SELECTOR<F>;
+    collectionSelector: STORE_SELECTOR<S, ENTITY_STATE<E>>;
+    idSelector: ID_SELECTOR<E>;
+    relationships: Array<HANDLER_RELATED_ENTITY<S, E>>;
     release(): void;
 };
 
-export type HANDLER_ROOT_ENTITIES<S, F, T, I> = {
+export type HANDLER_ROOT_ENTITIES<S, E, T, I> = {
     (state: S, id: Array<I>): Array<T>;
     ngrxEntityRelationship: string;
-    idSelector: ID_SELECTOR<F>;
+    collectionSelector: STORE_SELECTOR<S, ENTITY_STATE<E>>;
+    idSelector: ID_SELECTOR<E>;
+    relationships: Array<HANDLER_RELATED_ENTITY<S, E>>;
     release(): void;
 };
 
@@ -64,7 +68,11 @@ export type HANDLER_RELATED_ENTITY<S, E> = {
         sourceIdSelector: ID_SELECTOR<any /* TODO has to be a related entity */>,
     ): string | undefined;
     ngrxEntityRelationship: string;
+    collectionSelector: STORE_SELECTOR<S, ENTITY_STATE<any /* TODO has to be a related entity */>>;
     idSelector: ID_SELECTOR<any /* TODO has to be a related entity */>;
+    relationships: Array<HANDLER_RELATED_ENTITY<S, any /* TODO has to be a related entity */>>;
+    keyId: keyof any;
+    keyValue: keyof any;
     release(): void;
 };
 
diff --git a/test/childEntity.spec.ts b/test/childEntity.spec.ts
index 47110aa87..a1723b956 100644
--- a/test/childEntity.spec.ts
+++ b/test/childEntity.spec.ts
@@ -9,14 +9,17 @@ describe('childEntity', () => {
         child?: Entity;
     };
 
-    it('marks callback with ngrxEntityRelationship key', () => {
-        const actual = childEntity<any, any, any, any, any>(jasmine.createSpy(), '', '');
+    it('marks callback with ngrxEntityRelationship key and passed args', () => {
+        const rel1: any = Symbol();
+        const rel2: any = Symbol();
+        const featureSelector = jasmine.createSpy();
+        const actual = childEntity<any, any, any, any, any>(featureSelector, 'myKeyId', 'myKeyValue', rel1, rel2);
         expect(actual).toEqual(jasmine.any(Function));
-        expect(actual).toEqual(
-            jasmine.objectContaining({
-                ngrxEntityRelationship: 'childEntity',
-            }),
-        );
+        expect(actual.ngrxEntityRelationship).toEqual('childEntity');
+        expect(actual.collectionSelector).toBe(featureSelector);
+        expect(actual.keyId).toEqual('myKeyId');
+        expect(actual.keyValue).toEqual('myKeyValue');
+        expect(actual.relationships).toEqual([rel1, rel2]);
     });
 
     it('does not set anything if there is no child entity', () => {
diff --git a/test/childrenEntities.spec.ts b/test/childrenEntities.spec.ts
index b2eb21306..6c901c12a 100644
--- a/test/childrenEntities.spec.ts
+++ b/test/childrenEntities.spec.ts
@@ -9,14 +9,17 @@ describe('childrenEntities', () => {
         child?: Array<Entity>;
     };
 
-    it('marks callback with ngrxEntityRelationship key', () => {
-        const actual = childrenEntities<any, any, any, any, any>(jasmine.createSpy(), '', '');
+    it('marks callback with ngrxEntityRelationship key and passed args', () => {
+        const rel1: any = Symbol();
+        const rel2: any = Symbol();
+        const featureSelector = jasmine.createSpy();
+        const actual = childrenEntities<any, any, any, any, any>(featureSelector, 'myKeyId', 'myKeyValue', rel1, rel2);
         expect(actual).toEqual(jasmine.any(Function));
-        expect(actual).toEqual(
-            jasmine.objectContaining({
-                ngrxEntityRelationship: 'childrenEntities',
-            }),
-        );
+        expect(actual.ngrxEntityRelationship).toEqual('childrenEntities');
+        expect(actual.collectionSelector).toBe(featureSelector);
+        expect(actual.keyId).toEqual('myKeyId');
+        expect(actual.keyValue).toEqual('myKeyValue');
+        expect(actual.relationships).toEqual([rel1, rel2]);
     });
 
     it('set an empty array if there are no child entities', () => {
diff --git a/test/relatedEntity.spec.ts b/test/relatedEntity.spec.ts
index c7c3ddb8e..36f2f710a 100644
--- a/test/relatedEntity.spec.ts
+++ b/test/relatedEntity.spec.ts
@@ -11,14 +11,23 @@ describe('relatedEntity', () => {
         parentsId?: Array<string | number>;
     };
 
-    it('marks callback with ngrxEntityRelationship key', () => {
-        const actual = relatedEntity<any, any, any, any, any, any, any>(jasmine.createSpy(), '', '');
-        expect(actual).toEqual(jasmine.any(Function));
-        expect(actual).toEqual(
-            jasmine.objectContaining({
-                ngrxEntityRelationship: 'relatedEntity',
-            }),
+    it('marks callback with ngrxEntityRelationship key and passed args', () => {
+        const rel1: any = Symbol();
+        const rel2: any = Symbol();
+        const featureSelector = jasmine.createSpy();
+        const actual = relatedEntity<any, any, any, any, any, any, any>(
+            featureSelector,
+            'myKeyId',
+            'myKeyValue',
+            rel1,
+            rel2,
         );
+        expect(actual).toEqual(jasmine.any(Function));
+        expect(actual.ngrxEntityRelationship).toEqual('relatedEntity');
+        expect(actual.collectionSelector).toBe(featureSelector);
+        expect(actual.keyId).toEqual('myKeyId');
+        expect(actual.keyValue).toEqual('myKeyValue');
+        expect(actual.relationships).toEqual([rel1, rel2]);
     });
 
     it('does not set anything if the related id is falsy', () => {
diff --git a/test/rootEntities.spec.ts b/test/rootEntities.spec.ts
index f69603584..8ba115d41 100644
--- a/test/rootEntities.spec.ts
+++ b/test/rootEntities.spec.ts
@@ -15,13 +15,16 @@ describe('rootEntities', () => {
     });
 
     it('marks callback with ngrxEntityRelationship key', () => {
-        const actual = rootEntities(jasmine.createSpy() as any);
+        const rootSelector: any = jasmine.createSpy();
+        rootSelector.relationships = Symbol();
+        rootSelector.collectionSelector = Symbol();
+        rootSelector.idSelector = Symbol();
+        const actual = rootEntities(rootSelector);
         expect(actual).toEqual(jasmine.any(Function));
-        expect(actual).toEqual(
-            jasmine.objectContaining({
-                ngrxEntityRelationship: 'rootEntities',
-            }),
-        );
+        expect(actual.ngrxEntityRelationship).toEqual('rootEntities');
+        expect(actual.collectionSelector).toBe(rootSelector.collectionSelector);
+        expect(actual.idSelector).toBe(rootSelector.idSelector);
+        expect(actual.relationships).toBe(rootSelector.relationships);
     });
 
     it('returns the same empty array on no ids', () => {
diff --git a/test/rootEntity.spec.ts b/test/rootEntity.spec.ts
index 4a856f494..b5c2a0f3d 100644
--- a/test/rootEntity.spec.ts
+++ b/test/rootEntity.spec.ts
@@ -15,13 +15,15 @@ describe('rootEntity', () => {
     });
 
     it('marks callback with ngrxEntityRelationship key', () => {
-        const actual = rootEntity(jasmine.createSpy());
+        const rel1: any = Symbol();
+        const rel2: any = Symbol();
+        const featureSelector = jasmine.createSpy();
+        // because rels aren't real rels we need to pass a transformer.
+        const actual = rootEntity(featureSelector, () => null, rel1, rel2);
         expect(actual).toEqual(jasmine.any(Function));
-        expect(actual).toEqual(
-            jasmine.objectContaining({
-                ngrxEntityRelationship: 'rootEntity',
-            }),
-        );
+        expect(actual.collectionSelector).toBe(featureSelector);
+        expect(actual.ngrxEntityRelationship).toEqual('rootEntity');
+        expect(actual.relationships).toEqual([rel1, rel2]);
     });
 
     it('returns undefined when the id is falsy', () => {