diff --git a/zcash_client_backend/src/data_api/chain.rs b/zcash_client_backend/src/data_api/chain.rs
index 4aa0f71f0..de2fcbb82 100644
--- a/zcash_client_backend/src/data_api/chain.rs
+++ b/zcash_client_backend/src/data_api/chain.rs
@@ -27,7 +27,8 @@ pub const ANCHOR_OFFSET: u32 = 10;
 /// This function does not mutate either of the databases.
 pub fn validate_combined_chain<
     E0,
-    E: From<Error<E0>>,
+    N,
+    E: From<Error<E0, N>>,
     P: consensus::Parameters,
     C: CacheOps<Error = E>,
     D: DBOps<Error = E>,
@@ -84,7 +85,7 @@ pub fn validate_combined_chain<
 
 /// Determines the target height for a transaction, and the height from which to
 /// select anchors, based on the current synchronised block chain.
-pub fn get_target_and_anchor_heights<E0, E: From<Error<E0>>, D: DBOps<Error = E>>(
+pub fn get_target_and_anchor_heights<E0, N, E: From<Error<E0, N>>, D: DBOps<Error = E>>(
     data: &D,
 ) -> Result<(BlockHeight, BlockHeight), E> {
     data.block_height_extrema().and_then(|heights| {
diff --git a/zcash_client_backend/src/data_api/error.rs b/zcash_client_backend/src/data_api/error.rs
index ba4376e22..5f68d5924 100644
--- a/zcash_client_backend/src/data_api/error.rs
+++ b/zcash_client_backend/src/data_api/error.rs
@@ -14,7 +14,7 @@ pub enum ChainInvalid {
 }
 
 #[derive(Debug)]
-pub enum Error<DbError> {
+pub enum Error<DbError, NoteId> {
     CorruptedData(&'static str),
     IncorrectHRPExtFVK,
     InsufficientBalance(u64, u64),
@@ -23,7 +23,7 @@ pub enum Error<DbError> {
     InvalidMemo(std::str::Utf8Error),
     InvalidNewWitnessAnchor(usize, TxId, BlockHeight, Node),
     InvalidNote,
-    InvalidWitnessAnchor(i64, BlockHeight),
+    InvalidWitnessAnchor(NoteId, BlockHeight),
     ScanRequired,
     TableNotEmpty,
     Bech32(bech32::Error),
@@ -36,16 +36,16 @@ pub enum Error<DbError> {
 }
 
 impl ChainInvalid {
-    pub fn prev_hash_mismatch<E>(at_height: BlockHeight) -> Error<E> {
+    pub fn prev_hash_mismatch<E, N>(at_height: BlockHeight) -> Error<E, N> {
         Error::InvalidChain(at_height, ChainInvalid::PrevHashMismatch)
     }
 
-    pub fn block_height_mismatch<E>(at_height: BlockHeight, found: BlockHeight) -> Error<E> {
+    pub fn block_height_mismatch<E, N>(at_height: BlockHeight, found: BlockHeight) -> Error<E, N> {
         Error::InvalidChain(at_height, ChainInvalid::BlockHeightMismatch(found))
     }
 }
 
-impl<E: fmt::Display> fmt::Display for Error<E> {
+impl<E: fmt::Display, N: fmt::Display> fmt::Display for Error<E, N> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match &self {
             Error::CorruptedData(reason) => write!(f, "Data DB is corrupted: {}", reason),
@@ -86,7 +86,7 @@ impl<E: fmt::Display> fmt::Display for Error<E> {
     }
 }
 
-impl<E: error::Error + 'static> error::Error for Error<E> {
+impl<E: error::Error + 'static, N: error::Error + 'static> error::Error for Error<E, N> {
     fn source(&self) -> Option<&(dyn error::Error + 'static)> {
         match &self {
             Error::InvalidMemo(e) => Some(e),
@@ -100,31 +100,31 @@ impl<E: error::Error + 'static> error::Error for Error<E> {
     }
 }
 
-impl<E> From<bech32::Error> for Error<E> {
+impl<E, N> From<bech32::Error> for Error<E, N> {
     fn from(e: bech32::Error) -> Self {
         Error::Bech32(e)
     }
 }
 
-impl<E> From<bs58::decode::Error> for Error<E> {
+impl<E, N> From<bs58::decode::Error> for Error<E, N> {
     fn from(e: bs58::decode::Error) -> Self {
         Error::Base58(e)
     }
 }
 
-impl<E> From<builder::Error> for Error<E> {
+impl<E, N> From<builder::Error> for Error<E, N> {
     fn from(e: builder::Error) -> Self {
         Error::Builder(e)
     }
 }
 
-impl<E> From<std::io::Error> for Error<E> {
+impl<E, N> From<std::io::Error> for Error<E, N> {
     fn from(e: std::io::Error) -> Self {
         Error::Io(e)
     }
 }
 
-impl<E> From<protobuf::ProtobufError> for Error<E> {
+impl<E, N> From<protobuf::ProtobufError> for Error<E, N> {
     fn from(e: protobuf::ProtobufError) -> Self {
         Error::Protobuf(e)
     }
diff --git a/zcash_client_backend/src/data_api/mod.rs b/zcash_client_backend/src/data_api/mod.rs
index b076f2760..780f6e2e6 100644
--- a/zcash_client_backend/src/data_api/mod.rs
+++ b/zcash_client_backend/src/data_api/mod.rs
@@ -1,7 +1,7 @@
 use zcash_primitives::{
     block::BlockHash,
     consensus::{self, BlockHeight},
-    merkle_tree::CommitmentTree,
+    merkle_tree::{CommitmentTree, IncrementalWitness},
     primitives::PaymentAddress,
     sapling::Node,
     transaction::components::Amount,
@@ -73,6 +73,11 @@ pub trait DBOps {
         block_height: BlockHeight,
     ) -> Result<Option<CommitmentTree<Node>>, Self::Error>;
 
+    fn get_witnesses(
+        &self,
+        block_height: BlockHeight,
+    ) -> Result<Vec<(Self::NoteId, IncrementalWitness<Node>)>, Self::Error>;
+
     //    fn get_witnesses(block_height: BlockHeight) -> Result<Box<dyn Iterator<Item = IncrementalWitness<Node>>>, Self::Error>;
     //
     //    fn get_nullifiers() -> Result<(Vec<u8>, Account), Self::Error>;
diff --git a/zcash_client_sqlite/src/error.rs b/zcash_client_sqlite/src/error.rs
index 97890a9c6..401125d0c 100644
--- a/zcash_client_sqlite/src/error.rs
+++ b/zcash_client_sqlite/src/error.rs
@@ -4,8 +4,10 @@ use zcash_primitives::transaction::builder;
 
 use zcash_client_backend::data_api::error::Error;
 
+use crate::NoteId;
+
 #[derive(Debug)]
-pub struct SqliteClientError(pub Error<rusqlite::Error>);
+pub struct SqliteClientError(pub Error<rusqlite::Error, NoteId>);
 
 impl fmt::Display for SqliteClientError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
@@ -13,8 +15,8 @@ impl fmt::Display for SqliteClientError {
     }
 }
 
-impl From<Error<rusqlite::Error>> for SqliteClientError {
-    fn from(e: Error<rusqlite::Error>) -> Self {
+impl From<Error<rusqlite::Error, NoteId>> for SqliteClientError {
+    fn from(e: Error<rusqlite::Error, NoteId>) -> Self {
         SqliteClientError(e)
     }
 }
diff --git a/zcash_client_sqlite/src/lib.rs b/zcash_client_sqlite/src/lib.rs
index 51dcee1da..a1eae4126 100644
--- a/zcash_client_sqlite/src/lib.rs
+++ b/zcash_client_sqlite/src/lib.rs
@@ -24,13 +24,15 @@
 //! [`CompactBlock`]: zcash_client_backend::proto::compact_formats::CompactBlock
 //! [`init_cache_database`]: crate::init::init_cache_database
 
-use rusqlite::Connection;
+use std::fmt;
 use std::path::Path;
 
+use rusqlite::Connection;
+
 use zcash_primitives::{
     block::BlockHash,
     consensus::{self, BlockHeight},
-    merkle_tree::CommitmentTree,
+    merkle_tree::{CommitmentTree, IncrementalWitness},
     primitives::PaymentAddress,
     sapling::Node,
     transaction::components::Amount,
@@ -52,9 +54,18 @@ pub mod query;
 pub mod scan;
 pub mod transact;
 
+#[derive(Debug, Copy, Clone)]
 pub struct AccountId(pub u32);
+
+#[derive(Debug, Copy, Clone)]
 pub struct NoteId(pub i64);
 
+impl fmt::Display for NoteId {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Note {}", self.0)
+    }
+}
+
 pub struct DataConnection(Connection);
 
 impl DataConnection {
@@ -146,6 +157,13 @@ impl DBOps for DataConnection {
     ) -> Result<Option<CommitmentTree<Node>>, Self::Error> {
         query::get_commitment_tree(self, block_height)
     }
+
+    fn get_witnesses(
+        &self,
+        block_height: BlockHeight,
+    ) -> Result<Vec<(Self::NoteId, IncrementalWitness<Node>)>, Self::Error> {
+        query::get_witnesses(self, block_height)
+    }
 }
 
 pub struct CacheConnection(Connection);
diff --git a/zcash_client_sqlite/src/query.rs b/zcash_client_sqlite/src/query.rs
index b34b92676..29382fede 100644
--- a/zcash_client_sqlite/src/query.rs
+++ b/zcash_client_sqlite/src/query.rs
@@ -4,7 +4,7 @@ use rusqlite::{OptionalExtension, NO_PARAMS};
 
 use zcash_primitives::{
     consensus::{self, BlockHeight},
-    merkle_tree::CommitmentTree,
+    merkle_tree::{CommitmentTree, IncrementalWitness},
     note_encryption::Memo,
     primitives::PaymentAddress,
     sapling::Node,
@@ -261,6 +261,30 @@ pub fn get_commitment_tree(
         .map_err(SqliteClientError::from)
 }
 
+pub fn get_witnesses(
+    data: &DataConnection,
+    block_height: BlockHeight,
+) -> Result<Vec<(NoteId, IncrementalWitness<Node>)>, SqliteClientError> {
+    let mut stmt_fetch_witnesses = data
+        .0
+        .prepare("SELECT note, witness FROM sapling_witnesses WHERE block = ?")?;
+    let witnesses = stmt_fetch_witnesses
+        .query_map(&[u32::from(block_height)], |row| {
+            let id_note = NoteId(row.get(0)?);
+            let data: Vec<u8> = row.get(1)?;
+            Ok(IncrementalWitness::read(&data[..]).map(|witness| (id_note, witness)))
+        })
+        .map_err(SqliteClientError::from)?;
+
+    let mut res = vec![];
+    for witness in witnesses {
+        // unwrap database error & IO error from IncrementalWitness::read
+        res.push(witness??);
+    }
+
+    Ok(res)
+}
+
 #[cfg(test)]
 mod tests {
     use rusqlite::Connection;
diff --git a/zcash_client_sqlite/src/scan.rs b/zcash_client_sqlite/src/scan.rs
index 976ff9da6..4686bb0a3 100644
--- a/zcash_client_sqlite/src/scan.rs
+++ b/zcash_client_sqlite/src/scan.rs
@@ -24,7 +24,7 @@ use zcash_primitives::{
     transaction::Transaction,
 };
 
-use crate::{error::SqliteClientError, CacheConnection, DataConnection};
+use crate::{error::SqliteClientError, CacheConnection, DataConnection, NoteId};
 
 struct CompactBlockRow {
     height: BlockHeight,
@@ -105,15 +105,7 @@ pub fn scan_cached_blocks<P: consensus::Parameters>(
         .map(|t| t.unwrap_or(CommitmentTree::new()))?;
 
     // Get most recent incremental witnesses for the notes we are tracking
-    let mut stmt_fetch_witnesses = data
-        .0
-        .prepare("SELECT note, witness FROM sapling_witnesses WHERE block = ?")?;
-    let witnesses = stmt_fetch_witnesses.query_map(&[u32::from(last_height)], |row| {
-        let id_note = row.get(0)?;
-        let data: Vec<_> = row.get(1)?;
-        Ok(IncrementalWitness::read(&data[..]).map(|witness| WitnessRow { id_note, witness }))
-    })?;
-    let mut witnesses: Vec<_> = witnesses.collect::<Result<Result<_, _>, _>>()??;
+    let mut witnesses = data.get_witnesses(last_height)?;
 
     // Get the nullifiers for the notes we are tracking
     let mut stmt_fetch_nullifiers = data
@@ -209,7 +201,7 @@ pub fn scan_cached_blocks<P: consensus::Parameters>(
 
         let txs = {
             let nf_refs: Vec<_> = nullifiers.iter().map(|(nf, acc)| (&nf[..], *acc)).collect();
-            let mut witness_refs: Vec<_> = witnesses.iter_mut().map(|w| &mut w.witness).collect();
+            let mut witness_refs: Vec<_> = witnesses.iter_mut().map(|w| &mut w.1).collect();
             scan_block(
                 params,
                 block,
@@ -225,9 +217,9 @@ pub fn scan_cached_blocks<P: consensus::Parameters>(
         {
             let cur_root = tree.root();
             for row in &witnesses {
-                if row.witness.root() != cur_root {
+                if row.1.root() != cur_root {
                     return Err(SqliteClientError(Error::InvalidWitnessAnchor(
-                        row.id_note,
+                        row.0,
                         last_height,
                     )));
                 }
@@ -305,7 +297,7 @@ pub fn scan_cached_blocks<P: consensus::Parameters>(
                 // - A note value will never exceed 2^63 zatoshis.
 
                 // First try updating an existing received note into the database.
-                let note_row = if stmt_update_note.execute(&[
+                let note_id = if stmt_update_note.execute(&[
                     (output.account as i64).to_sql()?,
                     output.to.diversifier().0.to_sql()?,
                     (output.note.value as i64).to_sql()?,
@@ -327,20 +319,17 @@ pub fn scan_cached_blocks<P: consensus::Parameters>(
                         nf.to_sql()?,
                         output.is_change.to_sql()?,
                     ])?;
-                    data.0.last_insert_rowid()
+                    NoteId(data.0.last_insert_rowid())
                 } else {
                     // It was there, so grab its row number.
                     stmt_select_note.query_row(
                         &[tx_row.to_sql()?, (output.index as i64).to_sql()?],
-                        |row| row.get(0),
+                        |row| row.get(0).map(NoteId),
                     )?
                 };
 
                 // Save witness for note.
-                witnesses.push(WitnessRow {
-                    id_note: note_row,
-                    witness: output.witness,
-                });
+                witnesses.push((note_id, output.witness));
 
                 // Cache nullifier for note (to detect subsequent spends in this scan).
                 nullifiers.push((nf, output.account));
@@ -352,11 +341,11 @@ pub fn scan_cached_blocks<P: consensus::Parameters>(
         for witness_row in witnesses.iter() {
             encoded.clear();
             witness_row
-                .witness
+                .1
                 .write(&mut encoded)
                 .expect("Should be able to write to a Vec");
             stmt_insert_witness.execute(&[
-                witness_row.id_note.to_sql()?,
+                (witness_row.0).0.to_sql()?,
                 u32::from(last_height).to_sql()?,
                 encoded.to_sql()?,
             ])?;
@@ -567,7 +556,7 @@ mod tests {
             self, fake_compact_block, fake_compact_block_spending, insert_into_cache,
             sapling_activation_height,
         },
-        AccountId, CacheConnection, DataConnection,
+        AccountId, CacheConnection, DataConnection, NoteId,
     };
 
     use super::scan_cached_blocks;
@@ -617,8 +606,8 @@ mod tests {
             Ok(_) => panic!("Should have failed"),
             Err(e) => {
                 assert_eq!(
-                    e.0.to_string(),
-                    ChainInvalid::block_height_mismatch::<rusqlite::Error>(
+                    e.to_string(),
+                    ChainInvalid::block_height_mismatch::<rusqlite::Error, NoteId>(
                         sapling_activation_height() + 1,
                         sapling_activation_height() + 2
                     )