odbc does not return any value from hbase table

[Paul Chin]

The below cod, querying an Hbase table, always returns an empty string so the length of the variable Page = 0. When executing the same SQL from SQLCI, it works OK the first time; if trying the second time, SQLCI core-dumps. I then start SQLCI again and it works, but only one time before a new core dump.

This is the snipped from my aps: So the ODBC driver in line 09 indicates that there are data returned and in line 10 it’s indicated that it’s not a NULL value, but after executing line 11, the variable Page is empty. I use the same method when talking to Trafodion tables and it works just fine.

Mind you, this is the html data of up-to 32K I’m retrieving so must have something to do with the length because if I retrieve the row_id, which is only 14 CHARS, it works ok.

      01 With CMDtraf
      02 .CommandTimeout = 60
      03 .Connection.Open()
      04 .Parameters.Add("@caseid", OdbcType.Char, 14)
      05 .CommandText = "SELECT col_value from hbase.""_CELL_"".""bjcases"" WHERE row_id = ?"
      06 .Prepare()
      07 .Parameters("@caseid").Value = CaseID
      08 Dim odbcreader As OdbcDataReader = .ExecuteReader()
      09 If odbcreader.HasRows Then
      10 If Not IsDBNull(odbcreader(0)) Then
      11 Page = odbcreader(0)
      12 Dim TheBrowser = CreateObject("InternetExplorer.Application")
      13 TheBrowser.Visible = True
      14 TheBrowser.Navigate(Page)
      15 Else
      16 labAlertMsg.Text = "Case page not found in Trafodion"
      17 End If
      18 End If
      19 odbcreader.Close()
      20 .Connection.Close()
      21 End With

So these are the 3 statements I have tried in line 05 (with double “” removed. Only in the code for syntax reason.
SELECT col_value from hbase."_CELL_"."bjcases" WHERE row_id = ?
SELECT CAST(col_value AS VARCHAR(1000)) from hbase."_CELL_"."bjcases" WHERE row_id = ?
SELECT LEFT(col_value,1000) from hbase."_CELL_"."bjcases" WHERE row_id = ?

[Benny Jensen (benny-jensen)]

I have a correction. I was using the wrong syntax for the select from Hbase. I have now changed it to this syntax which works just fine in sqlci returned the page information, but in ODBC it just fails. It does not even throw an error. The applications just fails back to desktop.

select column_lookup(column_details, 'page:html') from hbase."_ROW_"."bjcases" WHERE row_id = '10-141101-4988';

[Anoop Sharma (anoop-sharma)]

The issue of empty string seems to be in odbc driver. Could be the use of a short var to store returned length.

A simpler testcase to reproduce this from odbc would be:

  select cast('a' as char(40000)) from (values(1)) x(a);
  This will return empty string.

  select cast('a' as char(30000)) from (values(a)) x(a);
  will return data.

[Daniel Lu (ping-lu)]

confirmed driver have row size < 32K limitation regarding ouput/fetch, will fix it.

not clear for input yet.