[PATCH] Use access() to check file existence in GetNewRelFileNode().

Previous code uses BasicOpenFile() + close(). access() should be faster than BasicOpenFile()+close() and access() should be more correct since BasicOpenFile() could fail for various cases (e.g. due to file permission, etc) even the file exists. access() is supported on Linux/Unix. I do not have

pg_ugprade test failure on data set with column with default value with type bit/varbit

Hello, While testing pg_upgrade we seemed to find an issue related to default value of a column with type bit/varbit. Below are the steps to reproduce. In this case we added two 'create table' DDLs in the regression database. Obviously we saw diff after pg_upgrade testing. The pg binaries are

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