TLobLocator.clear => access violation in orageneric10.dll

[Zugg]

Hello,

when I call Clear method on a TLobLocator some times it generated an access violation on orageneric10.dll : Violation d'acc

 

[Marco Kalter]

Can you show me the complete program code?

 

[Zugg]

Hi Marco,

here is the function code :

function MyFunction(vObj, vTest: TCouple): TResultat;
var
  LOB11, LOB12, LOB14, lob17: TLobLocator;
  qrySearch, qryList: TOracleQuery;
begin
  qrySearch := TOracleQuery.Create(nil);
  qrySearch.Session := OraSessionEtude2;

  qryList := TOracleQuery.Create(nil);
  qryList.Session := OraSessionEtude2;
  qryList.SQL.Text := <....>;
  qryList.DeclareVariable('vT4_C6', OtInteger);
  qryList.DeclareVariable('vT4_C7', OtInteger);

  try
    qrySearch.SQL.AddStrings(qrySearch_.SQL);
    qrySearch.DeclareAndSet('vT3_C6', OtInteger, vObj.poste);
    qrySearch.DeclareAndSet('vT3_C7', OtInteger, vObj.cle);
    qrySearch.DeclareAndSet('vT3_C8', OtInteger, vTest.Poste);
    qrySearch.DeclareAndSet('vT3_C9', OtInteger, vTest.cle);
    qrySearch.execute;
    if qrySearch.rowcount > 0 then
    begin
      try
        // Retrieve Result informations
	      <....>
        // Retrieve LOB
        LOB11 := qrySearch.LOBField('T3_C11');
        if not LOB11.IsNull then
          Result.item := LOB11.asString;
        LOB12 := qrySearch.LOBField('T3_C12');
        if not LOB12.IsNull then
          Result.donnee := LOB12.asString;

        LOB14 := qrySearch.LOBField('T3_C14');
        if not LOB14.IsNull then
          Result.Question := LOB14.asString;

        LOB17 := qrySearch.LOBField('T3_C17');
        if not LOB17.IsNull then
          Result.Commentaire := LOB17.asString;
        // on recupere les champs + les data
        qryList.SetVariable('vT4_C6', qrySearch.fieldasInteger('T3_C1'));
        qryList.SetVariable('vT4_C7', qrySearch.fieldasInteger('T3_C2'));
        qryList.Execute;
        while not qryList.Eof do
        begin
          // test pour compatibilite avec les anciennes versions
          <...>
          qryList.Next;
        end;
        qryList.Close;
      finally
        // Initialize Result with default value
        <...>
        LOB11.Clear;
        LOB12.Clear;
        LOB14.Clear;
        lob17.Clear;
        qrySearch.Close;
      end;
    end
    else
    begin
      qrySearch.close;
      // Initialize Result with default value
      <...>
    end;
  finally
    qrySearch.Clear;
    FreeAndNil(qrySearch);
    qryList.Clear;
    FreeAndNil(qryList);
  end;
end;

In this code, I have tried to make a LOB.free but it generate a problem too, so I would like to use a LOB.Clear to clean memory data in LOB variable.

I have also made a test with Oracle 10.2.0.3 in Windows Vista and it's the same problem.

 

[Marco Kalter]

You should not free, clear, or otherwise modify the TLOBLocator instances returned by the LOBField method. They are managed by the TOracleQuery instance.

 

[Zugg]

Thanks Marco,

but another question, why are there no bug with Oracle 9i ?
after migrating to Oracle 10g, I have found this problem but in 9i version, whith LOB.Clear (which you not recommanded) there were no access violation ?

Have you an idea why it doesn't not work (and make access violation) under Oracle 10g ?

 

[Marco Kalter]

Not really. Apparently 9i handles this differently than 10g.