69 lines
3.1 KiB
Markdown
69 lines
3.1 KiB
Markdown
(note: this is a temporary file, to be added-to by anybody, and moved to
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release-notes at release time)
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Notable changes
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===============
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Overwinter network upgrade
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--------------------------
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The code preparations for the Overwinter network upgrade, as described in [ZIP
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200](https://github.com/zcash/zips/blob/master/zip-0200.rst), [ZIP
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201](https://github.com/zcash/zips/blob/master/zip-0201.rst), [ZIP
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202](https://github.com/zcash/zips/blob/master/zip-0202.rst), [ZIP
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203](https://github.com/zcash/zips/blob/master/zip-0203.rst), and [ZIP
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143](https://github.com/zcash/zips/blob/master/zip-0143.rst) are
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finished and included in this release. Overwinter will activate on testnet at
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height 207500, and can also be activated at a specific height in regtest mode
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by setting the config option `-nuparams=5ba81b19:HEIGHT`.
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However, because the Overwinter activation height is not yet specified for
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mainnet, version 1.0.15 will behave similarly as other pre-Overwinter releases
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even after a future activation of Overwinter on the network. Upgrading from
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1.0.15 will be required in order to follow the Overwinter network upgrade on
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mainnet.
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Overwinter transaction format
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-----------------------------
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Once Overwinter has activated, transactions must use the new v3 format
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(including coinbase transactions). All RPC methods that create new transactions
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(such as `createrawtransaction` and `getblocktemplate`) will create v3
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transactions once the Overwinter activation height has been reached.
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Overwinter transaction expiry
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-----------------------------
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Overwinter transactions created by `zcashd` will also have a default expiry
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height set (the block height after which the transaction becomes invalid) of 20
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blocks after the height of the next block. This can be configured with the
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config option `-txexpirydelta`.
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UTXO and note merging
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---------------------
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In order to simplify the process of combining many small UTXOs and notes into a
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few larger ones, a new RPC method `z_mergetoaddress` has been added. It merges
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funds from t-addresses, z-addresses, or both, and sends them to a single
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t-address or z-address.
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Unlike most other RPC methods, `z_mergetoaddress` operates over a particular
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quantity of UTXOs and notes, instead of a particular amount of ZEC. By default,
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it will merge 50 UTXOs and 10 notes at a time; these limits can be adjusted with
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the parameters `transparent_limit` and `shielded_limit`.
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`z_mergetoaddress` also returns the number of UTXOs and notes remaining in the
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given addresses, which can be used to automate the merging process (for example,
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merging until the number of UTXOs falls below some value).
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UTXO memory accounting
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----------------------
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The default `-dbcache` has been changed in this release to 450MiB. Users can set
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`-dbcache` to a higher value (e.g. to keep the UTXO set more fully cached in
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memory). Users on low-memory systems (such as systems with 1GB or less) should
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consider specifying a lower value for this parameter.
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Additional information relating to running on low-memory systems can be found
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here: [reducing-memory-usage.md](https://github.com/zcash/zcash/blob/master/doc/reducing-memory-usage.md).
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