fix(core): improve tag list performance (#11353)

packages/frontend/core/src/modules/tag/entities/tag-list.ts

@@ -60,7 +60,6 @@ export class TagList extends Entity {
         id: tag.id,
         title: get(tag.value$),
         color: get(tag.color$),
-        pageCount: get(tag.pageIds$).length,
         createDate: get(tag.createDate$),
         updatedDate: get(tag.updateDate$),
       };

packages/frontend/core/src/modules/tag/entities/tag.ts

@@ -64,14 +64,5 @@ export class Tag extends Entity<{ id: string }> {
     });
   }
 
-  /**
-   * @deprecated performance issue here, use with caution until it is fixed
-   * @fixme(EYHN): page.meta$ has performance issue
-   */
-  readonly pageIds$ = LiveData.computed(get => {
-    const pages = get(this.docs.list.docs$);
-    return pages
-      .filter(page => get(page.meta$).tags?.includes(this.id))
-      .map(page => page.id);
-  });
+  readonly pageIds$ = LiveData.from(this.store.watchTagPageIds(this.id), []);
 }

packages/frontend/core/src/modules/tag/stores/tag.ts

@@ -1,8 +1,14 @@
 import type { Tag, Tag as TagSchema } from '@affine/env/filter';
 import type { DocsPropertiesMeta } from '@blocksuite/affine/store';
-import { LiveData, Store } from '@toeverything/infra';
+import {
+  LiveData,
+  Store,
+  yjsObserveByPath,
+  yjsObserveDeep,
+} from '@toeverything/infra';
 import { nanoid } from 'nanoid';
-import { Observable } from 'rxjs';
+import { map, Observable, switchMap } from 'rxjs';
+import { Array as YArray } from 'yjs';
 
 import type { WorkspaceService } from '../../workspace';
 
@@ -119,4 +125,32 @@ export class TagStore extends Store {
       ...tagInfo,
     });
   }
+
+  watchTagPageIds(id: string) {
+    return yjsObserveByPath(
+      this.workspaceService.workspace.rootYDoc.getMap('meta'),
+      'pages'
+    ).pipe(
+      switchMap(yjsObserveDeep),
+      map(meta => {
+        if (meta instanceof YArray) {
+          return meta
+            .map(v => {
+              const tags = v.get('tags') as YArray<string> | undefined;
+              if (tags instanceof YArray) {
+                for (const tagId of tags.toArray()) {
+                  if (tagId === id) {
+                    return v.get('id') as string;
+                  }
+                }
+              }
+              return null;
+            })
+            .filter(Boolean) as string[];
+        } else {
+          return [];
+        }
+      })
+    );
+  }
 }