本文档旨在为创建和评估参数变更提案提供指导。 起草并提交参数变更治理提案涉及两类风险：一是损失提案保证金，二是可能以不理想的方式改变 Cosmos Hub 网络的运行。

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可以更改哪些参数？

Cosmos Hub 的全部参数被划分到不同模块中，每个模块都有自己的一组参数。大多数参数都可以通过提交治理提案来更新。 可通过治理修改参数的模块列表：
  • x/auth
  • x/bank
  • x/distribution
  • x/evidence
  • x/feegrant
  • x/gov
  • x/mint
  • x/slashing
  • x/staking
  • ibc-go/transfer
  • interchain-security/provider
各个 cosmos-sdk 模块都使用 MsgUpdateParams 来提交参数变更。你可以在各模块的 cosmos-sdk 文档中了解更多信息（例如：链接）

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当前参数值是什么？

可以查询各模块参数的当前设置。其中一些可以通过命令行程序 gaiad 查询。 你可以先使用命令 gaiad q [module] -h 查看要查询模块的子命令帮助。例如，gaiad q staking params 会返回相关参数设置： 
bond_denom: uatom
historical_entries: 10000
max_entries: 7
max_validators: 180
unbonding_time: 1814400s
如果参数变更提案通过，变更会在投票期结束后立即生效。 注意： 目前你无法查询 bank 模块的参数 sendenabled。你也无法查询 crisis 模块的参数。

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为什么要创建参数变更提案？

参数决定了链在许多方面的行为。随着环境和社区态度的变化，你有时可能希望调整某个参数，使链的行为与社区意见保持一致。例如，Cosmos Hub 启动时只有 100 个活跃验证人，迄今已有 4 个提案提高了 MaxValidators 参数。在撰写本文时，活跃验证人集合包含 180 个验证人。 Cosmos Hub 一直被视为一条变更节奏较慢但安全性很高的链，这一点也体现在其其他一些参数上，例如 21 天的解绑期和 14 天的投票期。与 Cosmos 生态中的其他链相比，这些时间都相当长

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参数变更提案的风险

由于参数决定了链的部分运行方式，对其进行修改所产生的影响可能超出表面上能立即看出的范围。 例如，缩短解绑期看起来似乎只会影响委托人将资产变现的速度，但它也可能对网络的整体安全性产生更大的影响，而这一点在初看时并不容易意识到。 这也是为什么在上链前进行充分讨论如此重要的原因之一：把提案可能带来的影响讨论清楚，是避免出现非预期后果的有效方式。
This documentation aims to provide guidelines for creating and assessing parameter-change proposals. Drafting and submitting a parameter-change governance proposal involves two kinds of risk: losing proposal deposit amounts and the potential to alter the function of the Cosmos Hub network in an undesirable way.

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What parameters can be changed?

The complete parameters of the Cosmos Hub are split up into different modules, each of which has its own set of parameters. Most parameters can be updated by submitting a governance proposal. List of modules whose parameters can be changed via governance:
  • x/auth
  • x/bank
  • x/distribution
  • x/evidence
  • x/feegrant
  • x/gov
  • x/mint
  • x/slashing
  • x/staking
  • ibc-go/transfer
  • interchain-security/provider
Each cosmos-sdk module uses MsgUpdateParams for providing parameter changes. You can learn more about it in the cosmos-sdk documentation of each module (e.g. Link)

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What are the current parameter values?

There are ways to query the current settings for each module’s parameter(s). Some can be queried with the command line program gaiad. You can begin by using the command gaiad q [module] -h to get help about the subcommands for the module you want to query. For example, gaiad q staking params returns the settings of relevant parameters: 
bond_denom: uatom
historical_entries: 10000
max_entries: 7
max_validators: 180
unbonding_time: 1814400s
If a parameter-change proposal is successful, the change takes effect immediately upon completion of the voting period. Note: You cannot currently query the bank module’s parameter, which is sendenabled. You also cannot query the crisis module’s parameters.

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Why create a parameter change proposal?

Parameters are what govern many aspects of the chain’s behaviour. As circumstances and attitudes change, sometimes you might want to change a parameter to bring the chain’s behaviour in line with community opinion. For example, the Cosmos Hub launched with 100 active validators and there have been 4 proposals to date that have increased the MaxValidators parameter. At the time of writing, the active set contains 180 validators. The Cosmos Hub has been viewed as a slow-moving, highly secure chain and that is reflected in some of its other parameters, such as a 21 day unbonding period and 14 day voting period. These are quite long compared to other chains in the Cosmos Ecosystem

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Risks in parameter change proposals

Because parameters dictate some of the ways in which the chain operates, changing them can have an impact beyond what is immediately obvious. For example, reducing the unbonding period might seem like the only effect is in how quickly delegators can liquidate their assets. It might also have a much greater impact on the overall security of the network that would be hard to realize at first glance. This is one of the reasons that having a thorough discussion before going on-chain is so important - talking through the impacts of a proposal is a great way to avoid unintended effects.