MIME-Version: 1.0
From: Marko Ristola <marko.ristola@bcplatforms.com>
Date: Fri, 7 May 2021 21:13:18 +0300
Message-ID: 
 <CALndGf+qOJc6ZPfEAJgs_+CkE01QtEMQVEumGURHzzA+MYOuwg@mail.gmail.com>
Subject: PostgreSQL ODBC mylog() uses lots of CPU in INTEGER field SQL query
To: pgsql-odbc@postgresql.org
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 <https://www.postgresql.org/message-id/CALndGf%2BqOJc6ZPfEAJgs_%2BCkE01QtEMQVEumGURHzzA%2BMYOuwg%40mail.gmail.com>
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I did a query of 4 million rows into an INTEGER field.

Linux perf shows following profile (hottest functions):

   9.91%  bc_sqlselect  psqlodbcw.so               [.] mylog
   9.64%  bc_sqlselect  psqlodbcw.so               [.]
QR_read_a_tuple_from_db
   4.83%  bc_sqlselect  psqlodbcw.so               [.]
copy_and_convert_field
   4.57%  bc_sqlselect  libpthread-2.17.so         [.] pthread_mutex_unlock
   4.51%  bc_sqlselect  libpthread-2.17.so         [.] pthread_mutex_lock
   4.40%  bc_sqlselect  psqlodbcw.so               [.]
SOCK_get_next_n_bytes.part.2
   3.93%  bc_sqlselect  psqlodbcw.so               [.] PGAPI_ExtendedFetch

Following patch removes the only mylog() call (not a macro)

from the PostgreSQL ODBC driver from consuming CPU:

(MYLOG() macro is used to avoid the heavy mylog() call.)


diff --git a/results.c b/results.c
index 1f6a12c..ec89600 100644
--- a/results.c
+++ b/results.c
@@ -4632,7 +4632,6 @@ SC_pos_add(StatementClass *stmt,
                        goto cleanup;
                }
                MYLOG(0, "addstr=%s\n", addstr.data);
-               mylog("addstr=%s\n", addstr.data);
                s.qstmt->exec_start_row = s.qstmt->exec_end_row = s.irow;
                s.updyes = TRUE;
                ret = PGAPI_ExecDirect(hstmt, (SQLCHAR *) addstr.data,
SQL_NTS, 0);


Best Regards, Marko Ristola

--
Marko Ristola
Software developer
BC Platforms

m. +358 40 593 2182
e. marko.ristola@bcplatforms.com
w. www.bcplatforms.com

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