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CH10: transaction pools: use modern term "mempool" instead

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David A. Harding 2023-05-18 14:07:46 -10:00
parent d850cc3414
commit a4609f5680
1 changed files with 18 additions and 19 deletions
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@ -1188,20 +1188,20 @@ You can find more instructions on running Bitcoin Core as a Tor hidden
service in the Bitcoin Core documentation (_docs/tor.md_) and various
online tutorials.
=== Transaction Pools
[[mempool]]
=== Mempools and orphan pools
((("Bitcoin network", "transaction pools")))((("transaction
pools")))((("memory pools (mempools)")))Almost every node on the Bitcoin
network maintains a temporary list of unconfirmed transactions called
the _memory pool_, _mempool_, or _transaction pool_. Nodes use this pool
the _memory pool_ (_mempool_). Nodes use this pool
to keep track of transactions that are known to the network but are not
yet included in the blockchain. For example, a wallet node will use the
transaction pool to track incoming payments to the user's wallet that
mempool to track incoming payments to the user's wallet that
have been received on the network but are not yet confirmed.
As transactions are received and verified, they are added to the
transaction pool and relayed to the neighboring nodes to propagate on
mempool and relayed to the neighboring nodes to propagate on
the network.
((("orphan pools")))((("transactions", "orphaned")))Some node
@ -1210,10 +1210,10 @@ If a transaction's inputs refer to a transaction that is not yet known,
such as a missing parent, the orphan transaction will be stored
temporarily in the orphan pool until the parent transaction arrives.
When a transaction is added to the transaction pool, the orphan pool is
When a transaction is added to the mempool, the orphan pool is
checked for any orphans that reference this transaction's outputs (its
children). Any matching orphans are then validated. If valid, they are
removed from the orphan pool and added to the transaction pool,
removed from the orphan pool and added to the mempool,
completing the chain that started with the parent transaction. In light
of the newly added transaction, which is no longer an orphan, the
process is repeated recursively looking for any further descendants,
@ -1222,26 +1222,25 @@ of a parent transaction triggers a cascade reconstruction of an entire
chain of interdependent transactions by re-uniting the orphans with
their parents all the way down the chain.
Both the transaction pool and orphan pool (where implemented) are stored
Both the mempool and orphan pool (where implemented) are stored
in local memory and are not saved on persistent storage; rather, they
are dynamically populated from incoming network messages. When a node
starts, both pools are empty and are gradually populated with new
transactions received on the network.
Some implementations of the Bitcoin client also maintain an UTXO
database or pool, which is the set of all unspent outputs on the
blockchain. Although the name "UTXO pool" sounds similar to the
transaction pool, it represents a different set of data. Unlike the
transaction and orphan pools, the UTXO pool is not initialized empty but
instead contains millions of entries of unspent transaction outputs,
Some implementations of the Bitcoin also maintain an UTXO
database, which is the set of all unspent outputs on the
blockchain. This represents a different set of data from the mempool. Unlike the
mempool and orphan pools, the UTXO database
contains millions of entries of unspent transaction outputs,
everything that is unspent from all the way back to the genesis block.
The UTXO pool may be housed in local memory or as an indexed database
The UTXO database is stored as a
table on persistent storage.
Whereas the transaction and orphan pools represent a single node's local
Whereas the mempool and orphan pools represent a single node's local
perspective and might vary significantly from node to node depending
upon when the node was started or restarted, the UTXO pool represents
upon when the node was started or restarted, the UTXO database represents
the emergent consensus of the network and therefore will vary little
between nodes. Furthermore, the transaction and orphan pools only
contain unconfirmed transactions, while the UTXO pool only contains
between nodes. Furthermore, the mempool and orphan pools only
contain unconfirmed transactions, while the UTXO database only contains
confirmed outputs.