feat: allow detaching from ancestor for timelines without writes (#7639)

The first implementation #7456 did not include `index_part.json` changes
in an attempt to keep amount of changes down. Tracks the historic
reparentings and earlier detach in `index_part.json`.

- `index_part.json` receives a new field `lineage: Lineage`
- `Lineage` is queried through RemoteTimelineClient during basebackup,
creating `PREV LSN: none` for the invalid prev record lsn just as it
would had been created for a newly created timeline
- as `struct IndexPart` grew, it is now boxed in places

Cc: #6994

pageserver/src/basebackup.rs

@@ -601,7 +601,7 @@ where
         // add zenith.signal file
         let mut zenith_signal = String::new();
         if self.prev_record_lsn == Lsn(0) {
-            if self.lsn == self.timeline.get_ancestor_lsn() {
+            if self.timeline.is_ancestor_lsn(self.lsn) {
                 write!(zenith_signal, "PREV LSN: none")
                     .map_err(|e| BasebackupError::Server(e.into()))?;
             } else {

pageserver/src/tenant/metadata.rs

@@ -214,12 +214,12 @@ impl TimelineMetadata {
         self.body.ancestor_timeline = Some(*timeline);
     }
 
-    pub fn detach_from_ancestor(&mut self, timeline: &TimelineId, ancestor_lsn: &Lsn) {
+    pub fn detach_from_ancestor(&mut self, branchpoint: &(TimelineId, Lsn)) {
         if let Some(ancestor) = self.body.ancestor_timeline {
-            assert_eq!(ancestor, *timeline);
+            assert_eq!(ancestor, branchpoint.0);
         }
         if self.body.ancestor_lsn != Lsn(0) {
-            assert_eq!(self.body.ancestor_lsn, *ancestor_lsn);
+            assert_eq!(self.body.ancestor_lsn, branchpoint.1);
         }
         self.body.ancestor_timeline = None;
         self.body.ancestor_lsn = Lsn(0);

pageserver/src/tenant/remote_timeline_client.rs

@@ -437,6 +437,19 @@ impl RemoteTimelineClient {
         }
     }
 
+    /// Returns true if this timeline was previously detached at this Lsn and the remote timeline
+    /// client is currently initialized.
+    pub(crate) fn is_previous_ancestor_lsn(&self, lsn: Lsn) -> bool {
+        // technically this is a dirty read, but given how timeline detach ancestor is implemented
+        // via tenant restart, the lineage has always been uploaded.
+        self.upload_queue
+            .lock()
+            .unwrap()
+            .initialized_mut()
+            .map(|uq| uq.latest_lineage.is_previous_ancestor_lsn(lsn))
+            .unwrap_or(false)
+    }
+
     fn update_remote_physical_size_gauge(&self, current_remote_index_part: Option<&IndexPart>) {
         let size: u64 = if let Some(current_remote_index_part) = current_remote_index_part {
             current_remote_index_part
@@ -628,7 +641,7 @@ impl RemoteTimelineClient {
         );
 
         let index_part = IndexPart::from(&*upload_queue);
-        let op = UploadOp::UploadMetadata(index_part, disk_consistent_lsn);
+        let op = UploadOp::UploadMetadata(Box::new(index_part), disk_consistent_lsn);
         self.metric_begin(&op);
         upload_queue.queued_operations.push_back(op);
         upload_queue.latest_files_changes_since_metadata_upload_scheduled = 0;
@@ -647,7 +660,14 @@ impl RemoteTimelineClient {
             let mut guard = self.upload_queue.lock().unwrap();
             let upload_queue = guard.initialized_mut()?;
 
+            let Some(prev) = upload_queue.latest_metadata.ancestor_timeline() else {
+                return Err(anyhow::anyhow!(
+                    "cannot reparent without a current ancestor"
+                ));
+            };
+
             upload_queue.latest_metadata.reparent(new_parent);
+            upload_queue.latest_lineage.record_previous_ancestor(&prev);
 
             self.schedule_index_upload(upload_queue);
 
@@ -670,9 +690,8 @@ impl RemoteTimelineClient {
             let mut guard = self.upload_queue.lock().unwrap();
             let upload_queue = guard.initialized_mut()?;
 
-            upload_queue
-                .latest_metadata
-                .detach_from_ancestor(&adopted.0, &adopted.1);
+            upload_queue.latest_metadata.detach_from_ancestor(&adopted);
+            upload_queue.latest_lineage.record_detaching(&adopted);
 
             for layer in layers {
                 upload_queue
@@ -1811,6 +1830,7 @@ impl RemoteTimelineClient {
                         latest_files: initialized.latest_files.clone(),
                         latest_files_changes_since_metadata_upload_scheduled: 0,
                         latest_metadata: initialized.latest_metadata.clone(),
+                        latest_lineage: initialized.latest_lineage.clone(),
                         projected_remote_consistent_lsn: None,
                         visible_remote_consistent_lsn: initialized
                             .visible_remote_consistent_lsn

pageserver/src/tenant/remote_timeline_client/index.rs

@@ -6,6 +6,7 @@ use std::collections::HashMap;
 
 use chrono::NaiveDateTime;
 use serde::{Deserialize, Serialize};
+use utils::id::TimelineId;
 
 use crate::tenant::metadata::TimelineMetadata;
 use crate::tenant::storage_layer::LayerName;
@@ -84,6 +85,9 @@ pub struct IndexPart {
 
     #[serde(rename = "metadata_bytes")]
     pub metadata: TimelineMetadata,
+
+    #[serde(default)]
+    pub(crate) lineage: Lineage,
 }
 
 impl IndexPart {
@@ -96,17 +100,19 @@ impl IndexPart {
     /// - 3: no longer deserialize `timeline_layers` (serialized format is the same, but timeline_layers
     ///      is always generated from the keys of `layer_metadata`)
     /// - 4: timeline_layers is fully removed.
-    const LATEST_VERSION: usize = 4;
+    /// - 5: lineage was added
+    const LATEST_VERSION: usize = 5;
 
     // Versions we may see when reading from a bucket.
-    pub const KNOWN_VERSIONS: &'static [usize] = &[1, 2, 3, 4];
+    pub const KNOWN_VERSIONS: &'static [usize] = &[1, 2, 3, 4, 5];
 
     pub const FILE_NAME: &'static str = "index_part.json";
 
     fn new(
         layers_and_metadata: &HashMap<LayerName, LayerFileMetadata>,
         disk_consistent_lsn: Lsn,
         metadata: TimelineMetadata,
+        lineage: Lineage,
     ) -> Self {
         let layer_metadata = layers_and_metadata
             .iter()
@@ -119,6 +125,7 @@ impl IndexPart {
             disk_consistent_lsn,
             metadata,
             deleted_at: None,
+            lineage,
         }
     }
 
@@ -147,6 +154,7 @@ impl IndexPart {
             &HashMap::new(),
             example_metadata.disk_consistent_lsn(),
             example_metadata,
+            Default::default(),
         )
     }
 }
@@ -155,8 +163,9 @@ impl From<&UploadQueueInitialized> for IndexPart {
     fn from(uq: &UploadQueueInitialized) -> Self {
         let disk_consistent_lsn = uq.latest_metadata.disk_consistent_lsn();
         let metadata = uq.latest_metadata.clone();
+        let lineage = uq.latest_lineage.clone();
 
-        Self::new(&uq.latest_files, disk_consistent_lsn, metadata)
+        Self::new(&uq.latest_files, disk_consistent_lsn, metadata, lineage)
     }
 }
 
@@ -184,8 +193,76 @@ impl From<&LayerFileMetadata> for IndexLayerMetadata {
     }
 }
 
+/// Limited history of earlier ancestors.
+///
+/// A timeline can have more than 1 earlier ancestor, in the rare case that it was repeatedly
+/// reparented by having an later timeline be detached from it's ancestor.
+#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize, Default)]
+pub(crate) struct Lineage {
+    /// Has the `reparenting_history` been truncated to [`Lineage::REMEMBER_AT_MOST`].
+    #[serde(skip_serializing_if = "is_false", default)]
+    reparenting_history_truncated: bool,
+
+    /// Earlier ancestors, truncated when [`Self::reparenting_history_truncated`]
+    ///
+    /// These are stored in case we want to support WAL based DR on the timeline. There can be many
+    /// of these and at most one [`Self::original_ancestor`]. There cannot be more reparentings
+    /// after [`Self::original_ancestor`] has been set.
+    #[serde(skip_serializing_if = "Vec::is_empty", default)]
+    reparenting_history: Vec<TimelineId>,
+
+    /// The ancestor from which this timeline has been detached from and when.
+    ///
+    /// If you are adding support for detaching from a hierarchy, consider changing the ancestry
+    /// into a `Vec<(TimelineId, Lsn)>` to be a path instead.
+    #[serde(skip_serializing_if = "Option::is_none", default)]
+    original_ancestor: Option<(TimelineId, Lsn, NaiveDateTime)>,
+}
+
+fn is_false(b: &bool) -> bool {
+    !b
+}
+
+impl Lineage {
+    const REMEMBER_AT_MOST: usize = 100;
+
+    pub(crate) fn record_previous_ancestor(&mut self, old_ancestor: &TimelineId) {
+        if self.reparenting_history.last() == Some(old_ancestor) {
+            // do not re-record it
+            return;
+        }
+
+        let drop_oldest = self.reparenting_history.len() + 1 >= Self::REMEMBER_AT_MOST;
+
+        self.reparenting_history_truncated |= drop_oldest;
+        if drop_oldest {
+            self.reparenting_history.remove(0);
+        }
+        self.reparenting_history.push(*old_ancestor);
+    }
+
+    pub(crate) fn record_detaching(&mut self, branchpoint: &(TimelineId, Lsn)) {
+        assert!(self.original_ancestor.is_none());
+
+        self.original_ancestor =
+            Some((branchpoint.0, branchpoint.1, chrono::Utc::now().naive_utc()));
+    }
+
+    /// The queried lsn is most likely the basebackup lsn, and this answers question "is it allowed
+    /// to start a read/write primary at this lsn".
+    ///
+    /// Returns true if the Lsn was previously a branch point.
+    pub(crate) fn is_previous_ancestor_lsn(&self, lsn: Lsn) -> bool {
+        self.original_ancestor
+            .as_ref()
+            .is_some_and(|(_, ancestor_lsn, _)| lsn == *ancestor_lsn)
+    }
+}
+
 #[cfg(test)]
 mod tests {
+    use std::str::FromStr;
+
     use super::*;
 
     #[test]
@@ -221,6 +298,7 @@ mod tests {
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
             deleted_at: None,
+            lineage: Lineage::default(),
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
@@ -261,6 +339,7 @@ mod tests {
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
             deleted_at: None,
+            lineage: Lineage::default(),
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
@@ -302,7 +381,8 @@ mod tests {
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
             deleted_at: Some(chrono::NaiveDateTime::parse_from_str(
-                "2023-07-31T09:00:00.123000000", "%Y-%m-%dT%H:%M:%S.%f").unwrap())
+                "2023-07-31T09:00:00.123000000", "%Y-%m-%dT%H:%M:%S.%f").unwrap()),
+            lineage: Lineage::default(),
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
@@ -347,6 +427,7 @@ mod tests {
             ])
             .unwrap(),
             deleted_at: None,
+            lineage: Lineage::default(),
         };
 
         let empty_layers_parsed = IndexPart::from_s3_bytes(empty_layers_json.as_bytes()).unwrap();
@@ -385,11 +466,58 @@ mod tests {
             ]),
             disk_consistent_lsn: "0/16960E8".parse::<Lsn>().unwrap(),
             metadata: TimelineMetadata::from_bytes(&[113,11,159,210,0,54,0,4,0,0,0,0,1,105,96,232,1,0,0,0,0,1,105,96,112,0,0,0,0,0,0,0,0,0,0,0,0,0,1,105,96,112,0,0,0,0,1,105,96,112,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
-            deleted_at: Some(chrono::NaiveDateTime::parse_from_str(
-                "2023-07-31T09:00:00.123000000", "%Y-%m-%dT%H:%M:%S.%f").unwrap()),
+            deleted_at: Some(parse_naive_datetime("2023-07-31T09:00:00.123000000")),
+            lineage: Lineage::default(),
+        };
+
+        let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
+        assert_eq!(part, expected);
+    }
+
+    #[test]
+    fn v5_indexpart_is_parsed() {
+        let example = r#"{
+            "version":5,
+            "layer_metadata":{
+                "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF420-00000000014EF499":{"file_size":23289856,"generation":1},
+                "000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF499-00000000015A7619":{"file_size":1015808,"generation":1}},
+                "disk_consistent_lsn":"0/15A7618",
+                "metadata_bytes":[226,88,25,241,0,46,0,4,0,0,0,0,1,90,118,24,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,78,244,32,0,0,0,0,1,78,244,32,0,0,0,16,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
+                "lineage":{
+                    "original_ancestor":["e2bfd8c633d713d279e6fcd2bcc15b6d","0/15A7618","2024-05-07T18:52:36.322426563"],
+                    "reparenting_history":["e1bfd8c633d713d279e6fcd2bcc15b6d"]
+                }
+        }"#;
+
+        let expected = IndexPart {
+            version: 5,
+            layer_metadata: HashMap::from([
+                ("000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF420-00000000014EF499".parse().unwrap(), IndexLayerMetadata {
+                    file_size: 23289856,
+                    generation: Generation::new(1),
+                    shard: ShardIndex::unsharded(),
+                }),
+                ("000000000000000000000000000000000000-FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF__00000000014EF499-00000000015A7619".parse().unwrap(), IndexLayerMetadata {
+                    file_size: 1015808,
+                    generation: Generation::new(1),
+                    shard: ShardIndex::unsharded(),
+                })
+            ]),
+            disk_consistent_lsn: Lsn::from_str("0/15A7618").unwrap(),
+            metadata: TimelineMetadata::from_bytes(&[226,88,25,241,0,46,0,4,0,0,0,0,1,90,118,24,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,78,244,32,0,0,0,0,1,78,244,32,0,0,0,16,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]).unwrap(),
+            deleted_at: None,
+            lineage: Lineage {
+                reparenting_history_truncated: false,
+                reparenting_history: vec![TimelineId::from_str("e1bfd8c633d713d279e6fcd2bcc15b6d").unwrap()],
+                original_ancestor: Some((TimelineId::from_str("e2bfd8c633d713d279e6fcd2bcc15b6d").unwrap(), Lsn::from_str("0/15A7618").unwrap(), parse_naive_datetime("2024-05-07T18:52:36.322426563"))),
+            },
         };
 
         let part = IndexPart::from_s3_bytes(example.as_bytes()).unwrap();
         assert_eq!(part, expected);
     }
+
+    fn parse_naive_datetime(s: &str) -> NaiveDateTime {
+        chrono::NaiveDateTime::parse_from_str(s, "%Y-%m-%dT%H:%M:%S.%f").unwrap()
+    }
 }