Question

I am trying to execute this SQL command:

SELECT page.page_namespace, pagelinks.pl_namespace, COUNT(*)      FROM page, pagelinks     WHERE          (page.page_namespace <=3 OR page.page_namespace = 12              OR page.page_namespace = 13         )          AND          (pagelinks.pl_namespace <=3 OR pagelinks.pl_namespace = 12              OR pagelinks.pl_namespace = 13         )         AND          (page.page_is_redirect = 0)         AND          pagelinks.pl_from = page.page_id      GROUP BY (page.page_namespace, pagelinks.pl_namespace)  ;  

When I do so, I get the following error:

    ERROR:  could not identify an ordering operator for type record     HINT:  Use an explicit ordering operator or modify the query.      ********** Error **********      ERROR: could not identify an ordering operator for type record     SQL state: 42883     Hint: Use an explicit ordering operator or modify the query. 

I have tried adding : ORDER BY (page.page_namespace, pagelinks.pl_namespace) ASC to the end of the query without success.

UPDATE:

I also tried this:

SELECT page.page_namespace, pagelinks.pl_namespace, COUNT(*)      FROM page, pagelinks     WHERE pagelinks.pl_from = page.page_id      GROUP BY (page.page_namespace, pagelinks.pl_namespace)  ;  

But I still get the same error.

Thx

Answer 1

I haven’t checked any documentation but the fact that you have your GROUP BY expression in parentheses looks unusual to me. What happens if you don’t use parentheses here?