Blockstore exact purge cleanup (#13946)

* Add failing test

* Clean up signature get

ledger/src/blockstore/blockstore_purge.rs

@@ -273,21 +273,13 @@ impl Blockstore {
                 .cloned()
                 .flat_map(|entry| entry.transactions)
             {
-                batch.delete::<cf::TransactionStatus>((0, transaction.signatures[0], slot))?;
-                batch.delete::<cf::TransactionStatus>((1, transaction.signatures[0], slot))?;
-                for pubkey in transaction.message.account_keys {
-                    batch.delete::<cf::AddressSignatures>((
-                        0,
-                        pubkey,
-                        slot,
-                        transaction.signatures[0],
-                    ))?;
-                    batch.delete::<cf::AddressSignatures>((
-                        1,
-                        pubkey,
-                        slot,
-                        transaction.signatures[0],
-                    ))?;
+                if let Some(&signature) = transaction.signatures.get(0) {
+                    batch.delete::<cf::TransactionStatus>((0, signature, slot))?;
+                    batch.delete::<cf::TransactionStatus>((1, signature, slot))?;
+                    for pubkey in transaction.message.account_keys {
+                        batch.delete::<cf::AddressSignatures>((0, pubkey, slot, signature))?;
+                        batch.delete::<cf::AddressSignatures>((1, pubkey, slot, signature))?;
+                    }
                 }
             }
         }
@@ -332,7 +324,15 @@ impl Blockstore {
 #[cfg(test)]
 pub mod tests {
     use super::*;
-    use crate::{blockstore::tests::make_slot_entries_with_transactions, get_tmp_ledger_path};
+    use crate::{
+        blockstore::tests::make_slot_entries_with_transactions, entry::next_entry_mut,
+        get_tmp_ledger_path,
+    };
+    use bincode::serialize;
+    use solana_sdk::{
+        hash::{hash, Hash},
+        message::Message,
+    };
 
     // check that all columns are either empty or start at `min_slot`
     fn test_all_empty_or_min(blockstore: &Blockstore, min_slot: Slot) {
@@ -1133,4 +1133,30 @@ pub mod tests {
         }
         Blockstore::destroy(&blockstore_path).expect("Expected successful database destruction");
     }
+
+    #[test]
+    fn test_purge_special_columns_exact_no_sigs() {
+        let blockstore_path = get_tmp_ledger_path!();
+        {
+            let blockstore = Blockstore::open(&blockstore_path).unwrap();
+
+            let slot = 1;
+            let mut entries: Vec<Entry> = vec![];
+            for x in 0..5 {
+                let mut tx = Transaction::new_unsigned(Message::default());
+                tx.signatures = vec![];
+                entries.push(next_entry_mut(&mut Hash::default(), 0, vec![tx]));
+                let mut tick = create_ticks(1, 0, hash(&serialize(&x).unwrap()));
+                entries.append(&mut tick);
+            }
+            let shreds = entries_to_test_shreds(entries, slot, slot - 1, true, 0);
+            blockstore.insert_shreds(shreds, None, false).unwrap();
+
+            let mut write_batch = blockstore.db.batch().unwrap();
+            blockstore
+                .purge_special_columns_exact(&mut write_batch, slot, slot + 1)
+                .unwrap();
+        }
+        Blockstore::destroy(&blockstore_path).expect("Expected successful database destruction");
+    }
 }