Implement parser support for all select modifiers

[Utkar5hM]

Description

Implemented support for the following select modifiers in the sqlparser:

[HIGH_PRIORITY]
[SQL_SMALL_RESULT]
[SQL_BIG_RESULT]
[SQL_BUFFER_RESULT]

Added simple test cases for each of the modifiers under go/vt/sqlparser/parse_test.go similarly to that of sql_calc_found_rows.

I'll update the semantics check for the following modifiers and sql_calc_found_rows in a separate PR as discussed on slack.

Related Issue(s)

Fixes #15318

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

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[dbussink]

@Utkar5hM You'll also need to update the other test fixtures. If you run them, it should tell you how you can copy over the new expectations.

[Utkar5hM]

• updated the test cases to support the select modifiers.

• I've added SQL_BUFFER_RESULT under non reserved keywords list in sql.y.

• made a change to the func testFile() to make the newly generated select_case.txt be easily copyable in case it's the correct one. Previously, a error generating statement would still produce a error output text even if the error is null and there is an actual output which would require a lot of manual work changing ERROR to OUTPUT and regenerating select_case.txt.

• However the particular test case at https://github.com/vitessio/vitess/blob/main/go/vt/sqlparser/testdata/select_cases.txt#L19706 which errored due to sql_big_result not being a modifier now passes.

INPUT
select sql_big_result distinct t1.a from t1,t2 order by t2.a;
END
ERROR
syntax error at position 31 near 'distinct'
END

now produces

OUTPUT
select distinct sql_big_result t1.a from t1, t2 order by t2.a asc

which I think should fail as it is still an incorrect query as can be seen below or is this fine here? :

[GuptaManan100]

HIGH_PRIORITY, SQL_SMALL_RESULT and SQL_BIG_RESULT need to be added to the reserved_keyword list.

[codecov]

Codecov Report

Attention: Patch coverage is 80.95238% with 4 lines in your changes missing coverage. Please review.

Project coverage is 68.68%. Comparing base (3cb61cd) to head (b92da94).
Report is 15 commits behind head on main.

Files	Patch %	Lines
go/vt/sqlparser/ast_format.go	50.00%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #16396   +/-   ##
=======================================
  Coverage   68.68%   68.68%           
=======================================
  Files        1548     1548           
  Lines      199084   199116   +32     
=======================================
+ Hits       136736   136766   +30     
- Misses      62348    62350    +2     

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[Utkar5hM]

I have updated the above.

Addition of SQL_BUFFER_RESULT seems to have caused 3 shift/reduce conflicts making static Code check workflow to fail.

1732: shift/reduce conflict (shift 1738(0), red'n 901(0)) on SQL_BUFFER_RESULT
state 1732
	select_options_opt:  select_options.    (901)
	select_options:  select_options.select_option 

	DISTINCT  shift 1734
	ALL  shift 1742
	DISTINCTROW  shift 1735
	SQL_NO_CACHE  shift 2367
	SQL_CACHE  shift 2368
	SQL_CALC_FOUND_ROWS  shift 1741
	SQL_SMALL_RESULT  shift 1739
	SQL_BIG_RESULT  shift 1740
	SQL_BUFFER_RESULT  shift 1738
	HIGH_PRIORITY  shift 1736
	STRAIGHT_JOIN  shift 1737
	.  reduce 901 (src line 4801)

	select_option  goto 2372

1727: shift/reduce conflict (shift 1738(0), red'n 900(0)) on SQL_BUFFER_RESULT
state 1727
	query_primary:  SELECT comment_opt.select_options_opt select_expression_list into_clause from_opt where_expression_opt group_by_opt having_opt named_windows_list_opt 
	query_primary:  SELECT comment_opt.select_options_opt select_expression_list from_opt where_expression_opt group_by_opt having_opt named_windows_list_opt 
	select_options_opt: .    (900)

	DISTINCT  shift 1734
	ALL  shift 1742
	DISTINCTROW  shift 1735
	SQL_NO_CACHE  shift 2367
	SQL_CACHE  shift 2368
	SQL_CALC_FOUND_ROWS  shift 1741
	SQL_SMALL_RESULT  shift 1739
	SQL_BIG_RESULT  shift 1740
	SQL_BUFFER_RESULT  shift 1738
	HIGH_PRIORITY  shift 1736
	STRAIGHT_JOIN  shift 1737
	.  reduce 900 (src line 4797)

	select_options  goto 1732
	select_options_opt  goto 1729
	select_option  goto 1733

1037: shift/reduce conflict (shift 1738(0), red'n 900(0)) on SQL_BUFFER_RESULT
state 1037
	query_expression:  SELECT comment_opt.cache_opt NEXT num_val for_from table_name 
	query_primary:  SELECT comment_opt.select_options_opt select_expression_list into_clause from_opt where_expression_opt group_by_opt having_opt named_windows_list_opt 
	query_primary:  SELECT comment_opt.select_options_opt select_expression_list from_opt where_expression_opt group_by_opt having_opt named_windows_list_opt 
	cache_opt: .    (887)
	select_options_opt: .    (900)

	DISTINCT  shift 1734
	ALL  shift 1742
	DISTINCTROW  shift 1735
	NEXT  reduce 887 (src line 4732)
	SQL_NO_CACHE  shift 1730
	SQL_CACHE  shift 1731
	SQL_CALC_FOUND_ROWS  shift 1741
	SQL_SMALL_RESULT  shift 1739
	SQL_BIG_RESULT  shift 1740
	SQL_BUFFER_RESULT  shift 1738
	HIGH_PRIORITY  shift 1736
	STRAIGHT_JOIN  shift 1737
	.  reduce 900 (src line 4797)

	cache_opt  goto 1728
	select_options  goto 1732
	select_options_opt  goto 1729
	select_option  goto 1733

I'm pretty new to yacc and been having a look into how to eliminate this conflicts. I might take some time understanding it.

[GuptaManan100]

I have fixed the shift-reduce conflicts for you.

[systay]

I was reading it wrong. This LGTM!