Retain result type after UNION as base type in T-SQL

[hopebo]

Description

When a base type such as money is UNIONed with another integer type, the result type will be fixeddecimal instead of money, which is inconsistent with SQL Server's behaviour. And could also cause some characters not displaying well due to inappropriate result type.

Issues Resolved

The root cause of the issue is Postgres will consider the base type of domain type as the result type. In Babelfish, money is implemented as a domain type of fixeddecimal. Actually, money is a base type in T-SQL, thus Babelfish should retain money type after UNION.

After a final type has determined by the optimizer, check if it's a base type in T-SQL. If it is, try to use the domain type as result type if the domain type has higher precision than other types.

BABEL-5242

Check List

• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is under the terms of the Apache 2.0 and PostgreSQL licenses, and grant any person obtaining a copy of the contribution permission to relicense all or a portion of my contribution to the PostgreSQL License solely to contribute all or a portion of my contribution to the PostgreSQL open source project.

For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[coveralls]

Pull Request Test Coverage Report for Build 12362083072

Details

• 7 of 7 (100.0%) changed or added relevant lines in 1 file are covered.
• 28 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.002%) to 74.824%

---

Files with Coverage Reduction	New Missed Lines	%
contrib/babelfishpg_tsql/src/pltsql_coerce.c	28	81.5%

Totals
Change from base Build 12352168391:	0.002%
Covered Lines:	46440
Relevant Lines:	62066

---

💛 - Coveralls

[Deepesh125]

shouldn't this be resolved as money??

[hopebo]

For this SQL, the expected behaviour should be raising an error. This is the output from SQL Server:

mssql@f209a6999266:/$ /opt/mssql-tools18/bin/sqlcmd -S localhost -U SA -P "<YourStrong@Passw0rd>" -C
1> SELECT 'unknown'
2> UNION
3> SELECT $1.0
4> UNION
5> SELECT N'xyz';
6> GO

Msg 235, Level 16, State 0, Server f209a6999266, Line 1
Cannot convert a char value to money. The char value has incorrect syntax.

[hopebo]

This is the output from Babel:

dev-dsk-zboli-2c-08732257 % sqlcmd -S localhost -U jdbc_user -P '12345678'
1> CREATE VIEW TestView AS SELECT traamo = $1.0;
2> GO
1> SELECT c.[name] AS [sys_types_user_type_id],
2>        TYPE_NAME(a.user_type_id) AS type_name_function_user_type_id
3> FROM sys.columns a
4>     INNER JOIN sys.objects b
5>         ON a.[object_id] = b.[object_id]
6>     LEFT JOIN sys.types c
7>         ON a.user_type_id = c.user_type_id
8> WHERE b.[name] = 'TestView'
9>     AND a.[name] = 'traamo';
10> GO
sys_types_user_type_id                                                                                                           type_name_function_user_type_id
-------------------------------------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
numeric                                                                                                                          numeric

[hopebo]

SQL Server:

1> CREATE VIEW TestView AS SELECT traamo = $1.0 FROM t1;
2> GO
1> SELECT c.[name] AS [sys_types_user_type_id],
2>        TYPE_NAME(a.user_type_id) AS type_name_function_user_type_id
3> FROM sys.columns a
4>     INNER JOIN sys.objects b
5>         ON a.[object_id] = b.[object_id]
6>     LEFT JOIN sys.types c
7>         ON a.user_type_id = c.user_type_id
8> WHERE b.[name] = 'TestView'
9>     AND a.[name] = 'traamo';
10> GO
sys_types_user_type_id                                                                                                           type_name_function_user_type_id
-------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------
money                                                                                                                            money