function RawCAS do not expose parameter 'ttl'

[tutububug]

in kvproto project, RawCASRequest defined and include the 'ttl' member, and tikv-server also deal the request with 'ttl' semantic. why does not exposed it to the client api? CAS with ttl seems very useful in many cases.

[disksing]

Thanks @tutububug I think it is a good idea. We may need your opinion /cc @iosmanthus

[iosmanthus]

For now, CAS with TTL is forbidden but removing this restriction should be fine, the next few pull requests for API v2 should fix this.

[dbjoa]

@iosmanthus Do you have any update for the issue?

[iosmanthus]

@iosmanthus Do you have any update for the issue?

For now, TiKV v5.4.0 has canceled this restriction, but client-go need modify some method signature to support this feature by add a Ttl parameter to grpc request.

[tutububug]

ok, thank you. I had forked repository of client-go to modify method signature.

-------- 原始邮件 -------- 发件人： iosmanthus @.> 日期： 2022年2月22日周二 15:58 收件人： tikv/client-go @.> 抄送： tutububug @.>, Mention @.> 主 题： Re: [tikv/client-go] function RawCAS do not expose parameter 'ttl' (Issue #371)

@iosmanthushttps://github.com/iosmanthus Do you have any update for the issue?

For now, TiKV v5.4.0 has canceled this restriction, but client-go need modify some method signature to support this feature by add a Ttl parameter to grpc request.

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[wenlive]

In go-client V2, the function CompareAndSwap will erase the expiration time of the key. E.g

rawClient.PutWithTTL key1 value1 100
//GetKeyTTL key1 ->*ttl ==100
oldValue :=rawClient.Get key1
previousValue, ok, err := rawClient.CompareAndSwap key1 oldValue newValue
//GetKeyTTL key1 ->*ttl == 0

As far as I know, tikv splices ttl in value and uses it as a compaction filter to delete the key after the life cycle. In tikv go-client, CompareAndSwap does not specify Ttl

        reqArgs := kvrpcpb.RawCASRequest{
		Key:   key,
		Value: newValue,
	}
	if previousValue == nil {
		reqArgs.PreviousNotExist = true
	} else {
		reqArgs.PreviousValue = previousValue
	}

	req := tikvrpc.NewRequest(tikvrpc.CmdRawCompareAndSwap, &reqArgs)
	req.MaxExecutionDurationMs = uint64(client.MaxWriteExecutionTime.Milliseconds())
	resp, _, err := c.sendReq(ctx, key, req, false)

Can I add new ttl to RawCASRequest? Also what can be done to update the value using CAS and keep the historical ttl?@iosmanthus

[tutububug]

hi, I raise a PR #943 to fix this. @iosmanthus