GitHub user my-ship-it edited a comment on the discussion: [Proposal] Enhanced
ORCA Parallel Planning to Align with PostgreSQL Planner
> ```c++
> class CDistributionSpecRandom : public CDistributionSpec
> {
> public:
> enum EDistributionLevel
> {
> EdlSegment, // Cross-segment distribution
> EdlWorker // Intra-segment distribution to worker threads
> };
> // New members
> EDistributionLevel m_edl; // Distribution level
> ULONG m_ulWorkers; // Number of workers
> CDistributionSpec *m_pdsSegmentBase; // Base segment distribution
> };
> ```
>
> expand CDistributionSpecRandom.
After going through following inherited classes from CDistributionSpec:
Inherited directly:
* CDistributionSpecAny
* CDistributionSpecRandom
* CDistributionSpecUniversal
* CDistributionSpecNonSingleton
* CDistributionSpecRouted
* CDistributionSpecReplicated
* CDistributionSpecSingleton
And inherited indirectly:
* CDistributionSpecHashed（from CDistributionSpecRandom）
* CDistributionSpecStrictRandom（from CDistributionSpecRandom）
* CDistributionSpecStrictHashed（from CDistributionSpecHashed）
* CDistributionSpecHashedNoOp（from CDistributionSpecHashed）
* CDistributionSpecStrictSingleton（from CDistributionSpecSingleton）
* CDistributionSpecNonReplicated（from CDistributionSpecSingleton）
We also need to consider CDistributionSpecReplicated for replicated table at
least.
For example,
```
create table rt1(a int, b int) with(parallel_workers=2) distributed replicated;
create table rt2(a int, b int) distributed replicated;
explain(locus, costs off) select * from rt1 join rt2 on rt2.b = rt1.a;
QUERY PLAN
--------------------------------------------------
Gather Motion 2:1 (slice1; segments: 2)
Locus: Entry
-> Parallel Hash Join
Locus: SegmentGeneralWorkers
Parallel Workers: 2
Hash Cond: (rt2.b = rt1.a)
-> Parallel Seq Scan on rt2
Locus: SegmentGeneralWorkers
Parallel Workers: 2
-> Parallel Hash
Locus: SegmentGeneral
-> Parallel Seq Scan on rt1
Locus: SegmentGeneralWorkers
Parallel Workers: 2
```
GitHub link:
https://github.com/apache/cloudberry/discussions/1316#discussioncomment-14427044
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