Remove sub-query for skipping featured posts when loading posts

Instead we will pass a collection of IDs to skip, which will be much more efficient
msasikanth · Apr 18, 2024 · 0123ce3 · 0123ce3
1 parent 4550508
commit 0123ce3
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Showing 3 changed files with 56 additions and 52 deletions.
diff --git a/shared/src/commonMain/kotlin/dev/sasikanth/rss/reader/home/HomePresenter.kt b/shared/src/commonMain/kotlin/dev/sasikanth/rss/reader/home/HomePresenter.kt
@@ -224,17 +224,56 @@ class HomePresenter(
     }
 
     private fun init() {
-      observableActiveSource.activeSource
-        .onEach { selectedSource ->
+      combine(observableActiveSource.activeSource, settingsRepository.postsType) {
+          activeSource,
+          postsType ->
+          Pair(activeSource, postsType)
+        }
+        .onEach { (activeSource, postsType) ->
           _state.update {
-            it.copy(activeSource = selectedSource, posts = null, featuredPosts = null)
+            it.copy(
+              activeSource = activeSource,
+              postsType = postsType,
+              featuredPosts = null,
+              posts = null
+            )
           }
         }
-        .combine(settingsRepository.postsType) { selectedSource, postsType ->
-          _state.update { it.copy(postsType = postsType) }
-          selectedSource to postsType
+        .flatMapLatest {
+          val postsType = _state.value.postsType
+          val activeSource = _state.value.activeSource
+
+          val unreadOnly =
+            when (postsType) {
+              PostsType.ALL,
+              PostsType.TODAY,
+              PostsType.LAST_24_HOURS -> null
+              PostsType.UNREAD -> true
+            }
+
+          val postsAfter =
+            when (postsType) {
+              PostsType.ALL,
+              PostsType.UNREAD -> Instant.DISTANT_PAST
+              PostsType.TODAY -> {
+                getTodayStartInstant()
+              }
+              PostsType.LAST_24_HOURS -> {
+                getLast24HourStart()
+              }
+            }
+
+          rssRepository.featuredPosts(
+            selectedFeedId = activeSource?.id,
+            unreadOnly = unreadOnly,
+            after = postsAfter
+          )
         }
-        .flatMapLatest { (selectedSource, postsType) ->
+        .onEach { featuredPosts ->
+          val featuredPostIds = featuredPosts.map { it.id }
+          val postsType = _state.value.postsType
+          val activeSource = _state.value.activeSource
+
           val unreadOnly =
             when (postsType) {
               PostsType.ALL,
@@ -258,24 +297,16 @@ class HomePresenter(
           val posts =
             createPager(config = createPagingConfig(pageSize = 20, enablePlaceholders = true)) {
                 rssRepository.posts(
-                  selectedFeedId = selectedSource?.id,
+                  selectedFeedId = activeSource?.id,
+                  featuredPostsIds = featuredPostIds,
                   unreadOnly = unreadOnly,
-                  after = postsAfter
+                  after = postsAfter,
                 )
               }
               .flow
               .cachedIn(coroutineScope)
 
-          rssRepository
-            .featuredPosts(
-              selectedFeedId = selectedSource?.id,
-              unreadOnly = unreadOnly,
-              after = postsAfter
-            )
-            .map { featuredPosts -> Pair(featuredPosts.toImmutableList(), posts) }
-        }
-        .onEach { (featuredPosts, posts) ->
-          _state.update { it.copy(featuredPosts = featuredPosts, posts = posts) }
+          _state.update { it.copy(featuredPosts = featuredPosts.toImmutableList(), posts = posts) }
         }
         .launchIn(coroutineScope)
 

diff --git a/shared/src/commonMain/kotlin/dev/sasikanth/rss/reader/repository/RssRepository.kt b/shared/src/commonMain/kotlin/dev/sasikanth/rss/reader/repository/RssRepository.kt
@@ -197,14 +197,15 @@ class RssRepository(
 
   fun posts(
     selectedFeedId: String?,
+    featuredPostsIds: List<String>,
     unreadOnly: Boolean? = null,
-    after: Instant = Instant.DISTANT_PAST
+    after: Instant = Instant.DISTANT_PAST,
   ): PagingSource<Int, PostWithMetadata> {
     return QueryPagingSource(
       countQuery =
         postQueries.count(
           sourceId = selectedFeedId,
-          featuredPostsLimit = NUMBER_OF_FEATURED_POSTS,
+          featuredPosts = featuredPostsIds,
           unreadOnly = unreadOnly,
           postsAfter = after,
         ),
@@ -213,7 +214,7 @@ class RssRepository(
       queryProvider = { limit, offset ->
         postQueries.posts(
           sourceId = selectedFeedId,
-          featuredPostsLimit = NUMBER_OF_FEATURED_POSTS,
+          featuredPosts = featuredPostsIds,
           unreadOnly = unreadOnly,
           postsAfter = after,
           limit = limit,

diff --git a/shared/src/commonMain/sqldelight/dev/sasikanth/rss/reader/database/Post.sq b/shared/src/commonMain/sqldelight/dev/sasikanth/rss/reader/database/Post.sq
@@ -34,21 +34,7 @@ WHERE
     post.sourceId = :sourceId OR
     feedGroup.id = :sourceId
   ) AND
-  -- Skip featured posts --
-  post.id NOT IN (
-    SELECT post.id FROM post
-    WHERE
-    (:unreadOnly IS NULL OR post.read != :unreadOnly) AND
-    (
-      :sourceId IS NULL OR
-      post.sourceId = :sourceId OR
-      feedGroup.id = :sourceId
-    ) AND
-    post.imageUrl IS NOT NULL AND
-    post.date > :postsAfter
-    ORDER BY post.date DESC LIMIT :featuredPostsLimit
-  ) AND
-  -- Skip featured posts --
+  post.id NOT IN :featuredPosts AND
   post.date > :postsAfter
 ORDER BY post.date DESC;
 
@@ -104,21 +90,7 @@ WHERE
     post.sourceId = :sourceId OR
     feedGroup.id = :sourceId
   ) AND
-  -- Skip featured posts --
-  post.id NOT IN (
-    SELECT post.id FROM post
-    WHERE
-    (:unreadOnly IS NULL OR post.read != :unreadOnly) AND
-    (
-      :sourceId IS NULL OR
-      post.sourceId = :sourceId OR
-      feedGroup.id = :sourceId
-    ) AND
-    post.imageUrl IS NOT NULL AND
-    post.date > :postsAfter
-    ORDER BY post.date DESC LIMIT :featuredPostsLimit
-  ) AND
-  -- Skip featured posts --
+  post.id NOT IN :featuredPosts AND
   post.date > :postsAfter
 ORDER BY post.date DESC
 LIMIT :limit OFFSET :offset;