From 97d1443ed989409456fdf410f2ada1c5987457f4 Mon Sep 17 00:00:00 2001
From: Joonas Koivunen <joonas@neon.tech>
Date: Tue, 22 Aug 2023 17:00:19 +0300
Subject: [PATCH] refactor: remove PersistentLayerDesc::is_incremental

---
 .../src/tenant/storage_layer/layer_desc.rs      | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/pageserver/src/tenant/storage_layer/layer_desc.rs b/pageserver/src/tenant/storage_layer/layer_desc.rs
index c91f18f240de..59ca0f33e0fd 100644
--- a/pageserver/src/tenant/storage_layer/layer_desc.rs
+++ b/pageserver/src/tenant/storage_layer/layer_desc.rs
@@ -28,13 +28,8 @@ pub struct PersistentLayerDesc {
     /// - For a frozen in-memory layer or a delta layer, this is a valid end bound.
     /// - An image layer represents snapshot at one LSN, so end_lsn is always the snapshot LSN + 1
     pub lsn_range: Range<Lsn>,
-    /// Whether this is a delta layer.
+    /// Whether this is a delta layer, and also, is this incremental.
     pub is_delta: bool,
-    /// Does this layer only contain some data for the key-range (incremental),
-    /// or does it contain a version of every page? This is important to know
-    /// for garbage collecting old layers: an incremental layer depends on
-    /// the previous non-incremental layer.
-    pub is_incremental: bool,
     /// File size
     pub file_size: u64,
 }
@@ -68,7 +63,6 @@ impl PersistentLayerDesc {
             key_range,
             lsn_range: Lsn(0)..Lsn(1),
             is_delta: false,
-            is_incremental: false,
             file_size: 0,
         }
     }
@@ -86,8 +80,6 @@ impl PersistentLayerDesc {
             key_range,
             lsn_range: Self::image_layer_lsn_range(lsn),
             is_delta: false,
-            // currently all image layers are non-incremental
-            is_incremental: false,
             file_size,
         }
     }
@@ -105,7 +97,6 @@ impl PersistentLayerDesc {
             key_range,
             lsn_range,
             is_delta: true,
-            is_incremental: true,
             file_size,
         }
     }
@@ -171,8 +162,12 @@ impl PersistentLayerDesc {
         self.tenant_id
     }
 
+    /// Does this layer only contain some data for the key-range (incremental),
+    /// or does it contain a version of every page? This is important to know
+    /// for garbage collecting old layers: an incremental layer depends on
+    /// the previous non-incremental layer.
     pub fn is_incremental(&self) -> bool {
-        self.is_incremental
+        self.is_delta
     }
 
     pub fn is_delta(&self) -> bool {