cursor use vs pg_stat_statements

[Andrew Dunstan]

The problem I'm writing about (h/t Simon Riggs for finding it) is
illustrated by the following snippet of java:

      public static void runtest(Connection conn) throws Exception {
        Statement stmt = conn.createStatement();
        stmt.setFetchSize(10);
        ResultSet rs = stmt.executeQuery("select oid, relfileid, relname from 
pg_class");
        int count = 100;
        while (rs.next() && count-- > 0) {
          System.out.print(".");
        }
        rs.close();
        stmt.commit();
        stmt.close();
        System.out.println("");
      }

When called, this prints out a line with 100 dots showing 100 lines were
fetched, but pg_stat_statements shows this:

    query | select oid, relfilenode, relname from pg_class
    calls | 1
    rows  | 10


suggesting only 10 rows were returned. It appears that only the first
"EXECUTE 10" command against the portal is counted. At the very least
this is a POLA violation, and it seems to be a bug. Maybe it's
documented somewhere but if so it's not obvious to me.


cheers


andrew


--
Andrew Dunstan
EDB: https://www.enterprisedb.com