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
