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Why does vsql can return all the records, while program using ODBC driver can't?

  • November 27, 2014
  • 2 replies
  • 20 views
Nan_Xiao

I do a simple test for Vertica:

ha=> insert into test(Name, City) values( 'Nan', 'Nanjing');   OUTPUT   --------        1  (1 row)    ha=> select node_name, wos_row_count, ros_row_count from projection_storage where anchor_table_name = 'test';     node_name   | wos_row_count | ros_row_count   ---------------+---------------+---------------   v_ha_node0001 |             1 |             3  (1 row)    ha=> select * from test;     ID   | Name |  City     --------+------+---------   250001 | Nan  | Nanjing   250002 | Nan  | Nanjing   250003 | Nan  | Nanjing   250004 | Nan  | Nanjing  (4 rows)

The select operation displays OK (the data in WOS and ROSall display).

Then I write a simple program which uses ODBC:

ret = SQLExecDirect(stmt_handle, (SQLCHAR*)"select * from test", SQL_NTS);  if (!SQL_SUCCEEDED(ret))  {      printf("Execute statement failed\n");      goto ERR;  }    while ((ret = SQLFetch(stmt_handle)) == SQL_SUCCESS)  {      row_num++;  }    printf("Row number is %d\n", row_num);

But the result is:

Row number is 3

It doesn’t count the data in WOS.

And the DbVisualizer also displays 3 rows of data: 
VXTML

Does it need some special option for using ODBC? Thanks very much in advance!

    2 replies

    id10t
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    • id10t
    • Participating Frequently
    • November 27, 2014
    Hi!

    GOTO???  Very interesting.

    How row_num variable is initialized?  If its initialized to ZERO so you got correct answer - you counts rows starts from ZERO: 
    0 => row 1 1 => row 2 2 => row 3 ... n => row [n-1]
    EXAMPLE 
    >>> rows = [
    ...     'row 01',
    ...     'row 02',
    ...     'row 03',
    ...     'row 04']
    >>> 
    >>> for (row_index, row) in enumerate(rows):
    ...     print 'Row index is: {:0>3}\t but row order is: {}'.format(row_index, row)
    ... 
    Row index is: 000  but row order is: row 01
    Row index is: 001  but row order is: row 02
    Row index is: 002  but row order is: row 03
    Row index is: 003  but row order is: row 04
    About DBViz:
    Check against Vertica system tables what query DBViz sends to Vertica.

    System Tables:
    --------------
    * sessions
    * query_requests


    Also you can find DBViz queries in a ODBC log file.

    Best, Idiot.
    Nan_Xiao
    • Nan_Xiao
    • Author
    • New Participant
    • November 27, 2014
    Thanks for your comment!
    The root cause has been found: http://stackoverflow.com/questions/27164238/why-does-vsql-can-return-all-the-records-while-program-u....
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