Speed-up a few hot queries on pds and bsky (#1518)

* hit index for notif unread count in appview

* fix index usage on pds account lookup by handle

* add index to blob tempkey column to support some hot queries

packages/bsky/src/api/app/bsky/notification/getUnreadCount.ts

@@ -1,3 +1,4 @@
+import { sql } from 'kysely'
 import { InvalidRequestError } from '@atproto/xrpc-server'
 import { Server } from '../../../../lexicon'
 import { countAll, notSoftDeletedClause } from '../../../../db/util'
@@ -22,15 +23,12 @@ export default function (server: Server, ctx: AppContext) {
         .innerJoin('record', 'record.uri', 'notification.recordUri')
         .where(notSoftDeletedClause(ref('actor')))
         .where(notSoftDeletedClause(ref('record')))
+        // Ensure to hit notification_did_sortat_idx, handling case where lastSeenNotifs is null.
         .where('notification.did', '=', requester)
-        .where((inner) =>
-          inner
-            .where('actor_state.lastSeenNotifs', 'is', null)
-            .orWhereRef(
-              'notification.sortAt',
-              '>',
-              'actor_state.lastSeenNotifs',
-            ),
+        .where(
+          'notification.sortAt',
+          '>',
+          sql`coalesce(${ref('actor_state.lastSeenNotifs')}, ${''})`,
         )
         .executeTakeFirst()
 

packages/pds/src/db/migrations/20230825T142507884Z-blob-tempkey-idx.ts

@@ -0,0 +1,13 @@
+import { Kysely } from 'kysely'
+
+export async function up(db: Kysely<unknown>): Promise<void> {
+  await db.schema
+    .createIndex('blob_tempkey_idx')
+    .on('blob')
+    .column('tempKey')
+    .execute()
+}
+
+export async function down(db: Kysely<unknown>): Promise<void> {
+  await db.schema.dropIndex('blob_tempkey_idx').execute()
+}

packages/pds/src/db/migrations/index.ts

@@ -63,3 +63,4 @@ export * as _20230808T172813122Z from './20230808T172813122Z-repo-rev'
 export * as _20230810T203412859Z from './20230810T203412859Z-action-duration'
 export * as _20230818T134357818Z from './20230818T134357818Z-runtime-flags'
 export * as _20230824T182048120Z from './20230824T182048120Z-remove-post-hierarchy'
+export * as _20230825T142507884Z from './20230825T142507884Z-blob-tempkey-idx'

packages/pds/src/services/account/index.ts

@@ -37,7 +37,13 @@ export class AccountService {
         if (handleOrDid.startsWith('did:')) {
           return qb.where('did_handle.did', '=', handleOrDid)
         } else {
-          return qb.where('did_handle.handle', '=', handleOrDid)
+          // lower() is a little hack to avoid using the handle trgm index here, which is slow. not sure why it was preferring
+          // the handle trgm index over the handle unique index. in any case, we end-up using did_handle_handle_lower_idx instead, which is fast.
+          return qb.where(
+            sql`lower(${ref('did_handle.handle')})`,
+            '=',
+            handleOrDid,
+          )
         }
       })
       .selectAll('user_account')