perf: optimize project list queries with batch fetching for tags and media

.sqlx/query-1bd6b8e70790c3bc84bd42182622a417f338c179fe01d8324691e374c6f98d58.json

@@ -0,0 +1,74 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "\n        SELECT \n            id,\n            project_id,\n            display_order,\n            media_type as \"media_type: MediaType\",\n            r2_base_path,\n            variants,\n            blurhash,\n            metadata\n        FROM project_media\n        WHERE project_id = ANY($1)\n        ORDER BY project_id, display_order ASC\n        ",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 1,
+        "name": "project_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 2,
+        "name": "display_order",
+        "type_info": "Int4"
+      },
+      {
+        "ordinal": 3,
+        "name": "media_type: MediaType",
+        "type_info": {
+          "Custom": {
+            "name": "media_type",
+            "kind": {
+              "Enum": [
+                "image",
+                "video"
+              ]
+            }
+          }
+        }
+      },
+      {
+        "ordinal": 4,
+        "name": "r2_base_path",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 5,
+        "name": "variants",
+        "type_info": "Jsonb"
+      },
+      {
+        "ordinal": 6,
+        "name": "blurhash",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 7,
+        "name": "metadata",
+        "type_info": "Jsonb"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "UuidArray"
+      ]
+    },
+    "nullable": [
+      false,
+      false,
+      false,
+      false,
+      false,
+      false,
+      true,
+      true
+    ]
+  },
+  "hash": "1bd6b8e70790c3bc84bd42182622a417f338c179fe01d8324691e374c6f98d58"
+}

.sqlx/query-fd27337c6fd48ad71bf840da7764907adcc47e9f69fa0d821640c2ed7cbff269.json

@@ -0,0 +1,52 @@
+{
+  "db_name": "PostgreSQL",
+  "query": "\n        SELECT pt.project_id, t.id, t.slug, t.name, t.icon, t.color\n        FROM tags t\n        JOIN project_tags pt ON t.id = pt.tag_id\n        WHERE pt.project_id = ANY($1)\n        ORDER BY pt.project_id, t.name ASC\n        ",
+  "describe": {
+    "columns": [
+      {
+        "ordinal": 0,
+        "name": "project_id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 1,
+        "name": "id",
+        "type_info": "Uuid"
+      },
+      {
+        "ordinal": 2,
+        "name": "slug",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 3,
+        "name": "name",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 4,
+        "name": "icon",
+        "type_info": "Text"
+      },
+      {
+        "ordinal": 5,
+        "name": "color",
+        "type_info": "Varchar"
+      }
+    ],
+    "parameters": {
+      "Left": [
+        "UuidArray"
+      ]
+    },
+    "nullable": [
+      false,
+      false,
+      false,
+      false,
+      true,
+      true
+    ]
+  },
+  "hash": "fd27337c6fd48ad71bf840da7764907adcc47e9f69fa0d821640c2ed7cbff269"
+}

src/db/media.rs

@@ -250,6 +250,53 @@ pub async fn get_media_for_project(
     .await
 }
 
+/// Batch fetch media for multiple projects in a single query.
+/// Returns a HashMap mapping project_id to its media items.
+pub async fn get_media_for_projects(
+    pool: &PgPool,
+    project_ids: &[Uuid],
+) -> Result<std::collections::HashMap<Uuid, Vec<DbProjectMedia>>, sqlx::Error> {
+    use std::collections::HashMap;
+
+    if project_ids.is_empty() {
+        return Ok(HashMap::new());
+    }
+
+    let rows = sqlx::query_as!(
+        DbProjectMedia,
+        r#"
+        SELECT 
+            id,
+            project_id,
+            display_order,
+            media_type as "media_type: MediaType",
+            r2_base_path,
+            variants,
+            blurhash,
+            metadata
+        FROM project_media
+        WHERE project_id = ANY($1)
+        ORDER BY project_id, display_order ASC
+        "#,
+        project_ids
+    )
+    .fetch_all(pool)
+    .await?;
+
+    let mut result: HashMap<Uuid, Vec<DbProjectMedia>> = HashMap::new();
+
+    // Initialize empty vecs for all requested project_ids
+    for &id in project_ids {
+        result.entry(id).or_default();
+    }
+
+    for media in rows {
+        result.entry(media.project_id).or_default().push(media);
+    }
+
+    Ok(result)
+}
+
 /// Get single media item by ID
 pub async fn get_media_by_id(
     pool: &PgPool,

src/db/projects.rs

@@ -6,9 +6,9 @@ use uuid::Uuid;
 
 use super::{
     ProjectStatus,
-    media::{ApiProjectMedia, DbProjectMedia, get_media_for_project},
+    media::{self, ApiProjectMedia, DbProjectMedia, get_media_for_project},
     slugify,
-    tags::{ApiTag, DbTag, get_tags_for_project},
+    tags::{self, ApiTag, DbTag, get_tags_for_project},
 };
 
 // Database model
@@ -182,13 +182,29 @@ pub async fn get_public_projects_with_tags(
 ) -> Result<Vec<(DbProject, Vec<DbTag>, Vec<DbProjectMedia>)>, sqlx::Error> {
     let projects = get_public_projects(pool).await?;
 
-    let mut result = Vec::new();
-    for project in projects {
-        let tags = get_tags_for_project(pool, project.id).await?;
-        let media = get_media_for_project(pool, project.id).await?;
-        result.push((project, tags, media));
+    if projects.is_empty() {
+        return Ok(Vec::new());
     }
 
+    // Collect project IDs for batch queries
+    let project_ids: Vec<Uuid> = projects.iter().map(|p| p.id).collect();
+
+    // Batch fetch all tags and media in 2 queries instead of N*2
+    let (tags_map, media_map) = tokio::try_join!(
+        tags::get_tags_for_projects(pool, &project_ids),
+        media::get_media_for_projects(pool, &project_ids),
+    )?;
+
+    // Assemble results
+    let result = projects
+        .into_iter()
+        .map(|project| {
+            let tags = tags_map.get(&project.id).cloned().unwrap_or_default();
+            let media = media_map.get(&project.id).cloned().unwrap_or_default();
+            (project, tags, media)
+        })
+        .collect();
+
     Ok(result)
 }
 
@@ -222,13 +238,29 @@ pub async fn get_all_projects_with_tags_admin(
 ) -> Result<Vec<(DbProject, Vec<DbTag>, Vec<DbProjectMedia>)>, sqlx::Error> {
     let projects = get_all_projects_admin(pool).await?;
 
-    let mut result = Vec::new();
-    for project in projects {
-        let tags = get_tags_for_project(pool, project.id).await?;
-        let media = get_media_for_project(pool, project.id).await?;
-        result.push((project, tags, media));
+    if projects.is_empty() {
+        return Ok(Vec::new());
     }
 
+    // Collect project IDs for batch queries
+    let project_ids: Vec<Uuid> = projects.iter().map(|p| p.id).collect();
+
+    // Batch fetch all tags and media in 2 queries instead of N*2
+    let (tags_map, media_map) = tokio::try_join!(
+        tags::get_tags_for_projects(pool, &project_ids),
+        media::get_media_for_projects(pool, &project_ids),
+    )?;
+
+    // Assemble results
+    let result = projects
+        .into_iter()
+        .map(|project| {
+            let tags = tags_map.get(&project.id).cloned().unwrap_or_default();
+            let media = media_map.get(&project.id).cloned().unwrap_or_default();
+            (project, tags, media)
+        })
+        .collect();
+
     Ok(result)
 }
 

src/db/tags.rs

@@ -244,6 +244,52 @@ pub async fn get_tags_for_project(
     .await
 }
 
+/// Batch fetch tags for multiple projects in a single query.
+/// Returns a HashMap mapping project_id to its tags.
+pub async fn get_tags_for_projects(
+    pool: &PgPool,
+    project_ids: &[Uuid],
+) -> Result<std::collections::HashMap<Uuid, Vec<DbTag>>, sqlx::Error> {
+    use std::collections::HashMap;
+
+    if project_ids.is_empty() {
+        return Ok(HashMap::new());
+    }
+
+    let rows = sqlx::query!(
+        r#"
+        SELECT pt.project_id, t.id, t.slug, t.name, t.icon, t.color
+        FROM tags t
+        JOIN project_tags pt ON t.id = pt.tag_id
+        WHERE pt.project_id = ANY($1)
+        ORDER BY pt.project_id, t.name ASC
+        "#,
+        project_ids
+    )
+    .fetch_all(pool)
+    .await?;
+
+    let mut result: HashMap<Uuid, Vec<DbTag>> = HashMap::new();
+
+    // Initialize empty vecs for all requested project_ids
+    for &id in project_ids {
+        result.entry(id).or_default();
+    }
+
+    for row in rows {
+        let tag = DbTag {
+            id: row.id,
+            slug: row.slug,
+            name: row.name,
+            icon: row.icon,
+            color: row.color,
+        };
+        result.entry(row.project_id).or_default().push(tag);
+    }
+
+    Ok(result)
+}
+
 pub async fn get_projects_for_tag(
     pool: &PgPool,
     tag_id: Uuid,