Exception inserting a record of type row(integer)

[nezihyigitbasi]

presto:nyigitbasi> desc row_test;
 Column |      Type      | Comment
--------+----------------+---------
 x      | row(A integer) |
(1 row)

presto:nyigitbasi> insert into row_test values(row(2));
Query 20160805_225100_00048_b6cxd failed: Insert query has mismatched column types: Table: [row(A integer)], Query: [integer]
com.facebook.presto.sql.analyzer.SemanticException: Insert query has mismatched column types: Table: [row(A integer)], Query: [integer]
        at com.facebook.presto.sql.analyzer.StatementAnalyzer.visitInsert(StatementAnalyzer.java:249)
        at com.facebook.presto.sql.analyzer.StatementAnalyzer.visitInsert(StatementAnalyzer.java:161)
        at com.facebook.presto.sql.tree.Insert.accept(Insert.java:61)
        at com.facebook.presto.sql.tree.AstVisitor.process(AstVisitor.java:22)
        at com.facebook.presto.sql.analyzer.Analyzer.analyze(Analyzer.java:62)
        at com.facebook.presto.execution.SqlQueryExecution.doAnalyzeQuery(SqlQueryExecution.java:273)
        at com.facebook.presto.execution.SqlQueryExecution.analyzeQuery(SqlQueryExecution.java:259)
        at com.facebook.presto.execution.SqlQueryExecution.start(SqlQueryExecution.java:223)
        at com.facebook.presto.execution.QueuedExecution.lambda$start$1(QueuedExecution.java:62)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

This part of the analyzer code smells bad to me, @martint any ideas?

[geraint0923]

I think the problem is that in (row(2)) the outer parentheses is considered to change the evaluate priority and ignored when evaluating type. So your query is actually like:
insert into row_test values row(2)
and row(2) will seem as (2) which represents a row of data but a data type row just like
insert into some_table values (1,2,3) where some_table(a integer, b integer, c integer).

You can try
insert into row_test values row(row(2))
which will force the parser to produce what you expect.

The syntax is also confusing me sometimes.

[nezihyigitbasi]

@geraint0923 thanks for the explanation. The double row call works with a cast insert into row_test values row(cast(row(2) as row(A integer)));.

But, is it just a confusion or is it a bug? row is interpreted differently within a values:

presto:nyigitbasi> select * from (values row(2));
 _col0
-------
     2
(1 row)

presto:nyigitbasi> select row(2);
   _col0
------------
 {field0=2}
(1 row)

presto:nyigitbasi> select * from (values row(row(2)));
   _col0
------------
 {field0=2}
(1 row)

[geraint0923]

@nezihyigitbasi I agree with you that it is a little confusing. But I think it is intentional. When we are using values, we are actually trying to create an inline table which might has more than one columns. So we need to have a way to specify a row with multiple columns in a table, here we choose to use row.so in values, non-row and outer row will be regarded as a row of data in a table.

BTW, I just checked the SqlBase.g4:

primaryExpression
    : NULL                                             #nullLiteral
    ...
    | '(' expression (',' expression)+ ')'             #rowConstructor
    | ROW '(' expression (',' expression)* ')'         #rowConstructor
    ...
    | '(' expression ')'                               #parenthesizedExpression
    ;

(...) is a row only if there are more than one elements in it, and that is why (row(2)) is the same as row(2) which will be unwrapped in values clause.

@martint Maybe we need to clarify it in the docs?