Inconsistent quoting of identifiers?!

[XSven]

I have a csv file data/cities.csv. I am using the DBI tables() method to list the qualified tables:

perl -MDBI -E "say DBI->connect( 'DBI:CSV:', undef, undef, { f_dir => 'data', f_ext => '.csv/r', f_schema => 'foo' } )->tables('%', '%', '%', 'TABLE');"
"foo".cities

The schema foo is quoted but the cities table name is not!

I am now trying to prepare the same qualified table name using the DBI quote_identifier() method

perl -MDBI -E "\$dbh = DBI->connect( 'DBI:CSV:', undef, undef, { f_dir => 'data', f_ext => '.csv/r', f_schema => 'foo' } ); say \$dbh->quote_identifier(undef, \$dbh->{f_schema}, 'cities')"
"foo"."cities"

This time both the schema foo and the table name cities is quoted. That's what I have expected too when listing the tables.

My solution:

SQL_IDENTIFIER_QUOTE_CHAR is undefined. After assigning the double quote character " to it the table listing is as expected.

perl -MDBI -E "say DBI->connect( 'DBI:CSV:', undef, undef, { f_dir => 'data', f_ext => '.csv/r', f_schema => 'foo' } )->tables('%', '%', '%', 'TABLE');"
"foo"."cities"

I haven't investigated the sideeffects that a change of SQL_IDENTIFIER_QUOTE_CHAR might cause.