Re: [VOTE] TiKV Graduation

Liu Tang

Thanks TOC for raising this concern.  I am Tang Liu, and I am speaking here both as a TiKV maintainer and a member of the broader eco-system & community.

It’s true that Placement Driver is an indispensable part for TiKV, as the meta store and central scheduling center.

The original rationale behind the current placement of PD (under PingCAP with TiDB, the distributed SQL database) is to take PD as a significant dependency library in the TiDB eco-system (TiKV included) and other TiKV-alike stores as well.

Besides TiKV, there are multiple major TiDB features or components that depend on PD. For example, Dashboard (, our visual diagnosis platform, depends on PD to obtain necessary data. Unistore (, a KV store in GO to quickly validate TiDB optimizations depends on PD to deploy and run. Some scenario based features like multi-data center are made possible by PD. Outside of TiDB, there are other projects building distributed KV stores based on PD. 

With a vibrant TiDB ecosystem of almost 1000 adopters and other PD based projects,  we believe PD has been in a health and sustained maintenance and has formed its own eco-system over time.  

However, if this could not clear the concern of TOC, we are willing to migrate the entire PD library to the TiKV project.

Liu Tang

Frederick Kautz <frederick@...> 于2020年8月11日周二 上午4:51写道:

It is described as "Placement driver for TiKV" and TiKV appears to have a strong dependency on it so perhaps pd should be considered part of TiKV? We should ask TiKV maintainers about this.

On Mon, Aug 10, 2020 at 1:20 PM Erin Boyd <eboyd@...> wrote:
Hi Liz,
We may have missed this.
I can take a look and get back to you asap.

On Mon, Aug 10, 2020, 2:17 PM Liz Rice <liz@...> wrote:
Finally reviewing the TiKV graduation application. Mostly it looks great to me but has there been any discussion of TiKV's dependency on I’m not familiar with PD so I’m just raising the question of whether this is reasonable. We have plenty of projects with dependencies (e.g. on very widely used database, or k8s use of etcd before etcd came into the foundation) but I’d like some reassurance about whether PD is in the same kind of class as these, or whether there is a Plan B in the event that for some reason PD were no longer to be maintained. Thoughts welcome! 

On Mon, 3 Aug 2020 at 08:46, <tl@...> wrote:
+1, NB

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