[#4984] improvement(core, doris): Add the random distribution strategy

[yuqi1129]

What changes were proposed in this pull request?

Add the random strategy instead of even for Distribution

Why are the changes needed?

Doris support random distribution instead of even.

Fix: #4984

Does this PR introduce any user-facing change?

N/A.

How was this patch tested?

IT

[mchades]

What are the differences between EVEN and RANDOM?

AFAIK, RANDOM is a kind of implementation of EVEN

[yuqi1129]

Both aim to balance the distribution of data to optimize performance, "Random" emphasizes more on the randomness of the data, while "Even" focuses on maintaining the uniformity of the distribution.

They are slightly different.

[yuqi1129]

@FANNG1 do you have any comments on this issue.

[FANNG1]

IMO, HASH, RANGE RANDOM are the implemetation how we do the distribution, even is the something like distribution result, both HASH and RANDOM are the implementation of EVEN

[mchades]

So it's recommend to remove EVEN? But I remember that @yuqi1129 has done research and there is a certain kind of table that uses EVEN as a distribution name

[FANNG1]

@yuqi1129 , do you remember which kind of table use even distribution, could it be replaced by round-robin or random?

[yuqi1129]

Please refer to
https://docs.aws.amazon.com/redshift/latest/dg/r_CREATE_TABLE_NEW.html#r_CREATE_TABLE_usage-examples
https://learn.microsoft.com/en-us/sql/t-sql/statements/create-table-azure-sql-data-warehouse?view=aps-pdw-2016-au7

[yuqi1129]

@jerryshao any thoughts on this point? #4991 depends on this one.

[jerryshao]

You guys have better background on this, you can have a off-line discussion and negotiate out a solution.

[yuqi1129]

We could not reach an agreement till now, so I postponed it to 0.7.0 as it's not a bugfix.

[jerryshao]

@yuqi1129 this should be merged before 0.7.0.

[yuqi1129]

@yuqi1129 this should be merged before 0.7.0.

Got it.

[yuqi1129]

Postpone this to 0.8.0 as it's not a big need.