Pruning

The blockchain prunes seven eighths of prunable tx data.
This saves about two thirds of the blockchain size, while
keeping the node useful as a sync source for an eighth
of the blockchain.

No other data is currently pruned.

There are three ways to prune a blockchain:

- run monerod with --prune-blockchain
- run "prune_blockchain" in the monerod console
- run the monero-blockchain-prune utility

The first two will prune in place. Due to how LMDB works, this
will not reduce the blockchain size on disk. Instead, it will
mark parts of the file as free, so that future data will use
that free space, causing the file to not grow until free space
grows scarce.

The third way will create a second database, a pruned copy of
the original one. Since this is a new file, this one will be
smaller than the original one.

Once the database is pruned, it will stay pruned as it syncs.
That is, there is no need to use --prune-blockchain again, etc.

1 files changed, 24 insertions, 2 deletions

diff --git a/src/blockchain_db/blockchain_db.cpp b/src/blockchain_db/blockchain_db.cpp
index c25798c1e..d3eefef6e 100644
--- a/src/blockchain_db/blockchain_db.cpp
+++ b/src/blockchain_db/blockchain_db.cpp
@@ -267,7 +267,10 @@ void BlockchainDB::pop_block(block& blk, std::vector<transaction>& txs)
 
   for (const auto& h : boost::adaptors::reverse(blk.tx_hashes))
   {
-    txs.push_back(get_tx(h));
+    cryptonote::transaction tx;
+    if (!get_tx(h, tx) && !get_pruned_tx(h, tx))
+      throw DB_ERROR("Failed to get pruned or unpruned transaction from the db");
+    txs.push_back(std::move(tx));
     remove_transaction(h);
   }
   remove_transaction(get_transaction_hash(blk.miner_tx));
@@ -280,7 +283,7 @@ bool BlockchainDB::is_open() const
 
 void BlockchainDB::remove_transaction(const crypto::hash& tx_hash)
 {
-  transaction tx = get_tx(tx_hash);
+  transaction tx = get_pruned_tx(tx_hash);
 
   for (const txin_v& tx_input : tx.vin)
   {
@@ -325,6 +328,17 @@ bool BlockchainDB::get_tx(const crypto::hash& h, cryptonote::transaction &tx) co
   return true;
 }
 
+bool BlockchainDB::get_pruned_tx(const crypto::hash& h, cryptonote::transaction &tx) const
+{
+  blobdata bd;
+  if (!get_pruned_tx_blob(h, bd))
+    return false;
+  if (!parse_and_validate_tx_base_from_blob(bd, tx))
+    throw DB_ERROR("Failed to parse transaction base from blob retrieved from the db");
+
+  return true;
+}
+
 transaction BlockchainDB::get_tx(const crypto::hash& h) const
 {
   transaction tx;
@@ -333,6 +347,14 @@ transaction BlockchainDB::get_tx(const crypto::hash& h) const
   return tx;
 }
 
+transaction BlockchainDB::get_pruned_tx(const crypto::hash& h) const
+{
+  transaction tx;
+  if (!get_pruned_tx(h, tx))
+    throw TX_DNE(std::string("pruned tx with hash ").append(epee::string_tools::pod_to_hex(h)).append(" not found in db").c_str());
+  return tx;
+}
+
 void BlockchainDB::reset_stats()
 {
   num_calls = 0;