fix: ParsedQuery subselect edge case

[etr2460]

SUMMARY

I found that aliased subselects would break the logic to extract table names from a query. When using sqlparse, it seemed like the query got expanded more than expected when the alias was added:

>>> import sqlparse
>>> sqlparse.parse("SELECT f1, (SELECT count(1) FROM t2) FROM t1")[0]._pprint_tree()
|- 0 DML 'SELECT'
|- 1 Whitespace ' '
|- 2 Identifier 'f1'
|  `- 0 Name 'f1'
|- 3 Punctuation ','
|- 4 Whitespace ' '
|- 5 Parenthesis '(SELEC...'
|  |- 0 Punctuation '('
|  |- 1 DML 'SELECT'
|  |- 2 Whitespace ' '
|  |- 3 Function 'count(...'
|  |  |- 0 Identifier 'count'
|  |  |  `- 0 Name 'count'
|  |  `- 1 Parenthesis '(1)'
|  |     |- 0 Punctuation '('
|  |     |- 1 Integer '1'
|  |     `- 2 Punctuation ')'
|  |- 4 Whitespace ' '
|  |- 5 Keyword 'FROM'
|  |- 6 Whitespace ' '
|  |- 7 Identifier 't2'
|  |  `- 0 Name 't2'
|  `- 8 Punctuation ')'
|- 6 Whitespace ' '
|- 7 Keyword 'FROM'
|- 8 Whitespace ' '
`- 9 Identifier 't1'
   `- 0 Name 't1'
>>> sqlparse.parse("SELECT f1, (SELECT count(1) FROM t2) as f2 FROM t1")[0]._pprint_tree()
|- 0 DML 'SELECT'
|- 1 Whitespace ' '
|- 2 IdentifierList 'f1, (S...'
|  |- 0 Identifier 'f1'
|  |  `- 0 Name 'f1'
|  |- 1 Punctuation ','
|  |- 2 Whitespace ' '
|  `- 3 Identifier '(SELEC...'
|     |- 0 Parenthesis '(SELEC...'
|     |  |- 0 Punctuation '('
|     |  |- 1 DML 'SELECT'
|     |  |- 2 Whitespace ' '
|     |  |- 3 Function 'count(...'
|     |  |  |- 0 Identifier 'count'
|     |  |  |  `- 0 Name 'count'
|     |  |  `- 1 Parenthesis '(1)'
|     |  |     |- 0 Punctuation '('
|     |  |     |- 1 Integer '1'
|     |  |     `- 2 Punctuation ')'
|     |  |- 4 Whitespace ' '
|     |  |- 5 Keyword 'FROM'
|     |  |- 6 Whitespace ' '
|     |  |- 7 Identifier 't2'
|     |  |  `- 0 Name 't2'
|     |  `- 8 Punctuation ')'
|     |- 1 Whitespace ' '
|     |- 2 Keyword 'as'
|     |- 3 Whitespace ' '
|     `- 4 Identifier 'f2'
|        `- 0 Name 'f2'
|- 3 Whitespace ' '
|- 4 Keyword 'FROM'
|- 5 Whitespace ' '
`- 6 Identifier 't1'
   `- 0 Name 't1'

This adds logic to recursively explore sections wrapped in parens, which seems safe and didn't break any of the existing tests while allowing mine to pass. That said, would love any thoughts on a better way to do this too

TEST PLAN

CI

to: @villebro @lilykuang @serenajiang @bkyryliuk @michellethomas

[codecov]

Codecov Report

Merging #13602 (4cc8dc5) into master (de0c6c9) will decrease coverage by 9.97%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #13602      +/-   ##
==========================================
- Coverage   80.93%   70.96%   -9.98%     
==========================================
  Files         304      828     +524     
  Lines       24807    41443   +16636     
  Branches        0     4300    +4300     
==========================================
+ Hits        20077    29409    +9332     
- Misses       4730    12034    +7304     

Flag	Coverage Δ
cypress	56.72% <ø> (?)
hive	?
mysql	80.37% <100.00%> (ø)
postgres	80.42% <100.00%> (ø)
presto	?
python	80.51% <100.00%> (-0.42%)	⬇️
sqlite	80.03% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
superset/sql_parse.py	99.38% <100.00%> (ø)
superset/db_engines/hive.py	0.00% <0.00%> (-85.72%)	⬇️
superset/db_engine_specs/hive.py	74.23% <0.00%> (-16.54%)	⬇️
superset/db_engine_specs/presto.py	81.79% <0.00%> (-6.91%)	⬇️
superset/views/database/mixins.py	81.03% <0.00%> (-1.73%)	⬇️
superset/db_engine_specs/base.py	85.67% <0.00%> (-0.49%)	⬇️
superset/models/core.py	88.55% <0.00%> (-0.28%)	⬇️
...ontrols/DndColumnSelectControl/DndMetricSelect.tsx	4.42% <0.00%> (ø)
...rset-frontend/src/components/ListView/ListView.tsx	92.04% <0.00%> (ø)
...teFilterControl/components/DateFunctionTooltip.tsx	100.00% <0.00%> (ø)
... and 521 more

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[serenajiang]

I thiiink this should be safe. Can you check to make sure other uses of parentheses like SELECT f1, (x + y) AS f2 FROM t1 work as expected?

[serenajiang]

item.is_group and (not self.is_identifier(item) or isinstance(item.tokens[0], Parenthesis))?

[etr2460]

i think it's equivalent, do you think it's as readable?

[etr2460]

add the parens test you recommended