avantgardnerio opened a new issue, #2889:
URL: https://github.com/apache/arrow-datafusion/issues/2889
**Is your feature request related to a problem or challenge? Please describe
what you are trying to do.**
A significant portion of my time on #2885 was spent manually formatting
subqueries like:
```
Projection: #SUM(lineitem.l_extendedprice) / Float64(7) AS avg_yearly
Aggregate: groupBy=[[]], aggr=[[SUM(#lineitem.l_extendedprice)]]
Filter: #part.p_brand = Utf8("Brand#23") AND #part.p_container =
Utf8("MED BOX") AND #lineitem.l_quantity < (Subquery: Projection: Float64(0.2)
* #AVG(lineitem.l_quantity)
Aggregate: groupBy=[[]], aggr=[[AVG(#lineitem.l_quantity)]]
Filter: #lineitem.l_partkey = #part.p_partkey
TableScan: lineitem)
Inner Join: #lineitem.l_partkey = #part.p_partkey
TableScan: lineitem
TableScan: part
```
into
```
Projection: #SUM(lineitem.l_extendedprice) / Float64(7) AS avg_yearly
Aggregate: groupBy=[[]], aggr=[[SUM(#lineitem.l_extendedprice)]]
Filter: #part.p_brand = Utf8("Brand#23") AND #part.p_container =
Utf8("MED BOX")
AND #lineitem.l_quantity < (
Subquery: Projection: Float64(0.2) * #AVG(lineitem.l_quantity)
Aggregate: groupBy=[[]], aggr=[[AVG(#lineitem.l_quantity)]]
Filter: #lineitem.l_partkey = #part.p_partkey
TableScan: lineitem
)
Inner Join: #lineitem.l_partkey = #part.p_partkey
TableScan: lineitem
TableScan: part
```
because the indents aren't trustworthy when subqueries are taken into
account.
Also, I've had a hard time writing unit tests for optimizers because
building them programmatically is verbose and error-prone.
**Describe the solution you'd like**
If we were to create a visitor method like `display_json()`, and an
equivalent `LogicalPlan::from_json()` then both problems would be solved fairly
elegantly. As a bonus, plans would be readable and manipulable by common off
the the shelf tools and readable by the uninitiated.
**Describe alternatives you've considered**
Fixing the indentation on the formatter, writing different types of tests,
crying into my beer.
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