Use an upsert for `FsBlockDb::write_block_metadata`

zcash_client_sqlite/CHANGELOG.md

@@ -20,6 +20,8 @@ and this library adheres to Rust's notion of
   wallet did not contain enough observed blocks to satisfy the `min_confirmations`
   value specified; this situation is now treated as an error.
 - A `BlockConflict` variant has been added to `zcash_client_sqlite::error::SqliteClientError`
+- `zcash_client_sqlite::FsBlockDb::write_block_metadata` now overwrites any
+  existing metadata entries that have the same height as a new entry.
 
 ### Removed
 - The empty `wallet::transact` module has been removed.

zcash_client_sqlite/src/chain.rs

@@ -103,21 +103,40 @@ pub(crate) fn blockmetadb_insert(
     conn: &Connection,
     block_meta: &[BlockMeta],
 ) -> Result<(), rusqlite::Error> {
+    use rusqlite::named_params;
+
     let mut stmt_insert = conn.prepare(
-        "INSERT INTO compactblocks_meta (height, blockhash, time, sapling_outputs_count, orchard_actions_count)
-        VALUES (?, ?, ?, ?, ?)"
+        "INSERT INTO compactblocks_meta (
+            height,
+            blockhash,
+            time,
+            sapling_outputs_count,
+            orchard_actions_count
+        )
+        VALUES (
+            :height,
+            :blockhash,
+            :time,
+            :sapling_outputs_count,
+            :orchard_actions_count
+        )
+        ON CONFLICT (height) DO UPDATE
+        SET blockhash = :blockhash,
+            time = :time,
+            sapling_outputs_count = :sapling_outputs_count,
+            orchard_actions_count = :orchard_actions_count",
     )?;
 
     conn.execute("BEGIN IMMEDIATE", [])?;
     let result = block_meta
         .iter()
         .map(|m| {
-            stmt_insert.execute(params![
-                u32::from(m.height),
-                &m.block_hash.0[..],
-                m.block_time,
-                m.sapling_outputs_count,
-                m.orchard_actions_count,
+            stmt_insert.execute(named_params![
+                ":height": u32::from(m.height),
+                ":blockhash": &m.block_hash.0[..],
+                ":time": m.block_time,
+                ":sapling_outputs_count": m.sapling_outputs_count,
+                ":orchard_actions_count": m.orchard_actions_count,
             ])
         })
         .collect::<Result<Vec<_>, _>>();

zcash_client_sqlite/src/lib.rs

@@ -907,7 +907,8 @@ impl FsBlockDb {
         Ok(chain::blockmetadb_get_max_cached_height(&self.conn)?)
     }
 
-    /// Adds a set of block metadata entries to the metadata database.
+    /// Adds a set of block metadata entries to the metadata database, overwriting any
+    /// existing entries at the given block heights.
     ///
     /// This will return an error if any block file corresponding to one of these metadata records
     /// is absent from the blocks directory.