Tracking: remove exchange after append-only source

[shanicky]

Due to the situation mentioned in the issue, we now need to remove the exchange that comes after the append-only source. Currently, the estimated tasks that need to be done are as follows:

• Add a new serial type that reuses int64.
  • Implement scalar type for serial. feat(common): introduce Serial as Scalar and ScalarRef #8327
  • Implement array type for serial. feat(common): introduce SerialArrayBuilder and SerialArray #8357
  • Implement logical type for serial. feat(common): Add support for DataType::Serial #8392
• Skipping hash for Serial type & Modify the plan generated by the frontend. feat: remove the exchange after append_only source #8532

Here are some possible issues that may arise:

For split, i.e., sources with a small number of partitions but huge traffic, a simple mv will result in limited compute capacity. For example, in a Kafka cluster with only 3 partitions but huge traffic, the parallelism of many fragments will be limited to 3.

Relevant links:

#7353
#7621

[xxchan]

Relevant link risingwavelabs/rfcs#45

[fuyufjh]

Hi, can I close this ?

[shanicky]

Hi, can I close this ?

Alright, let me close it now