Обсуждение: Re: 回复: Core dump happens when execute sql CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10));

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Re: 回复: Core dump happens when execute sql CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10));

От
Tom Lane
Дата:
Yulin PEI <ypeiae@connect.ust.hk> writes:
>     After several tests, I found that this patch do not fix the bug well.

What do you think is wrong with it?

> So the attachment is my patch and it works well as far as I tested.

This seems equivalent to the already-committed patch [1] except that
it wastes a makeNode call in the coerce-to-uncollatable-type case.

            regards, tom lane

[1] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=c402b02b9fb53aee2a26876de90a8f95f9a9be92

回覆: 回复: Core dump happens when execute sql CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10));

От
Yulin PEI
Дата:
Consider the SQL statement 'SELECT (('1' COLLATE "C") ||(B'1'));' . Intuitively, the result will be '11' and the result is '11' in pg 13.2 release as well.

The function stack is make_fn_arguments -> coerce_type, which means that the param "Node *node" of function coerce_type could be a CollateExpr Node.
Let's look at your patch:

```
// node is ('1' COLLATE "C")
// targetType is varbit and it is non-collatable
if (IsA(node, CollateExpr) && type_is_collatable(targetTypeId))
{
// we will not reach here.
 
CollateExpr *coll = (CollateExpr *) node;
CollateExpr *newcoll = makeNode(CollateExpr);
 ....
 
// An error will be generated. "failed to find conversion function"
 
}

```

So I suggest:

```
// node is ('1' COLLATE "C")
if (IsA(node, CollateExpr))
   {
      CollateExpr *coll = (CollateExpr *) node;
      CollateExpr *newcoll = makeNode(CollateExpr);


      //targetType is varbit and it is non-collatable
 
      if (!type_is_collatable(targetTypeId)) {
 
         // try to convert '1'(string) to varbit 
 
         // We do not make a new CollateExpr here, but don't forget to coerce coll->arg.
         return coerce_type(pstate, (Node *) coll->arg,
                        inputTypeId, targetTypeId, targetTypeMod,
                        ccontext, cformat, location);
      }
     ...
   }
```






寄件者: Tom Lane <tgl@sss.pgh.pa.us>
寄件日期: 2021年4月19日 1:46
收件者: Yulin PEI <ypeiae@connect.ust.hk>
副本: pgsql-hackers@lists.postgresql.org <pgsql-hackers@lists.postgresql.org>
主旨: Re: 回复: Core dump happens when execute sql CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10));
 
Yulin PEI <ypeiae@connect.ust.hk> writes:
 >     After several tests, I found that this patch do not fix the bug well.

 What do you think is wrong with it?

 > So the attachment is my patch and it works well as far as I tested.

 This seems equivalent to the already-committed patch [1] except that
 it wastes a makeNode call in the coerce-to-uncollatable-type case.

                         regards, tom lane

 [1]  https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=c402b02b9fb53aee2a26876de90a8f95f9a9be92

			
		

		
	

	
	
							

	
	

	

		

			
Re: 回覆: 回复: Core dump happens when execute sql CREATE VIEW v1(c1) AS (SELECT ('4' COLLATE "C")::INT FROM generate_series(1, 10));

									
		    

		        
От
 
		    	
Tom Lane

		    

		    

		        
Дата:

		        




			

		

	

	
							
						
	

	

		

			
				
Yulin PEI <ypeiae@connect.ust.hk> writes:
> Let's look at your patch:

> ```
> // node is ('1' COLLATE "C")
> // targetType is varbit and it is non-collatable
> if (IsA(node, CollateExpr) && type_is_collatable(targetTypeId))
> {

> // we will not reach here.

That's not the committed patch, though.  I realized after posting
it that it didn't maintain the same behavior in coerce_type as
coerce_to_target_type.  But the actually-committed fix does, and
as I said, what you're suggesting seems equivalent though a bit
messier.

            regards, tom lane