Can anyone suggest why the following custom filter causes re-entrancy to the custom filter "master" function (ie the oone assigned to the engine)?

end else if (CompareText(FunctionName, 'ScanAttachments') = 0) then begin
 Result := not FunctionParams[0].IsNull;
 if FunctionParams[1].Asinteger = 30169 then showmessage('here');
 if Result then begin
  Result := False;
  AttTbl := MakeDBISAMTable('AF' + IntToStr(GetTickCount), 'Memory', tfrSession);
  AttTbl.TableName := MakeImgAttMemTable('AF' + IntToStr(GetTickCount), 'A', tfrSession);
  fileBumph := TMemoryStream.Create;
  TMemoField(FunctionParams[0]).SaveToStream(fileBumph);<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< RE-ENTRANCY
  fileBumph.Free;
  AttTbl.LoadFromStream(fileBumph);
  while (not Result) and (not AttTbl.Eof) do begin
  //roy
  if  0<>pos('vincent',lowerCase(AttTbl.FieldByName('_Name').AsString)) then showmessage('xx');
  //roy
   tmpStr := AttTbl.FieldByName('_Item').AsString;
   Result := CheckTextMatch(nil, FunctionParams[2].AsString, tmpstr);
   AttTbl.Next;
  end;
  ZapInMemoryTable(AttTbl);
 end;

The function is designed to check documents stored in a table which is turn stored in a memo field in a table.

Roy Lambert

I thought I'd found it - freeing the memory stream before I used it. But I've fixed that and still have the problem.

Roy Lambert

I think I'm finally understanding things. The ftMemo type applied to functionparams simply means STRING. No wonder I can't get it to stream.


I've come up with a solution since all I want to do is simple string matching I can just do it on the whole of the memo field. I'm lucky I had no compression set for it.

Now a question for Tim.

In ElevateDB will the default compression still be zero. So that as in this case I store documents in a memo field in a memory table and then store that in a memo field in a disk table when I pass the disk memo field through as a parameter to a custom function I can test the string OR is compression going to be a default in which case I've had it.

Roy Lambert

Final (I hope) question. The onprogress doesn't seem to fire. Any idea?


The current form of the filter is

 Result := not FunctionParams[0].IsNull;
 if Result then begin
  Result := False;
  tmpStr := LowerCase(FunctionParams[0].AsMemo);
  Result := CheckTextMatch(nil, FunctionParams[1].AsString, tmpstr);
 end;


Roy Lambert


function Tdm.CheckTextMatch(const strm: TMemoryStream; const Checklist: string; WorkStr: string): boolean;
var
fileData: TStringStream;
fileString: string;
const
MustContain = 1;
MightContain = 2;
MustNotContain = 3;
function MatchedText(WhichBlock: integer; const Blank: boolean): boolean;
var
 TestStrings: string;
 Fld: integer;
 CompStr: string;
 iResult: boolean;
begin
 Result := Blank;
 TestStrings := SubFld(CheckList, RecSep, WhichBlock);
 if TestStrings = '' then Exit;
 Result := WhichBlock = 1;
 Fld := 1;
 CompStr := SubFld(TestStrings, StrSep, Fld);
 while CompStr <> '' do begin
  iResult := 0 <> Pos(CompStr, WorkStr);
  case WhichBlock of
   MustContain: if not iResult then begin
     Result := False;
     Exit;
    end;
   MightContain, MustNotContain: if iResult then begin
     Result := True;
     Exit;
    end;
  end;
  inc(Fld);
  CompStr := SubFld(TestStrings, StrSep, Fld);
 end;
end;
begin
if strm <> nil then begin
 fileData := TStringStream.Create(fileString);
 strm.Position := 0;
 strm.SaveToStream(fileData);
 WorkStr := LowerCase(fileData.DataString);
 fileData.Free;
end;
Result := MatchedText(MustContain, True) and MatchedText(MightContain, True) and (not MatchedText(MustNotContain, False));
end;

Roy,

<< In ElevateDB will the default compression still be zero. >>

Yes.  But it doesn't really matter since the compression is only "on disk"
and never affects BLOBs that are opened and in memory.

--
Tim Young
Elevate Software
www.elevatesoft.com

Roy,

<< Final (I hope) question. The onprogress doesn't seem to fire. Any idea?
>>

Which OnProgress - the OnQueryProgress ?

--
Tim Young
Elevate Software
www.elevatesoft.com

Tim


>Which OnProgress - the OnQueryProgress ?

Yup. But strangely enough with the same custom filter but just using a single table (same one actually) rather than a joined wadge it does work.


So Select * FROM MandN WHERE ScanAttachments(_Attachments,'vincent..') the OnProgress event works OK


Select _ID FROM Contacts
JOIN MandN ON MandN._fkContacts = _ID
...
...
...
WHERE
ScanAttachments(_Attachments,'vincent..')

the OnProgress event seems to do nothing until the end then it goes from 0% - 100% FAST.

BTW is there a way of getting a table stored in a memo field back into a table in a custom function using FunctionParams?

Roy Lambert

Roy,

<< the OnProgress event seems to do nothing until the end then it goes from
0% - 100% FAST. >>

That's the way it works when there is a brute-force filter that can be
applied directly to the source table.  Basically the query engine evaluates
it like this:

Select _ID FROM Contacts
JOIN (SELECT * FROM MandN WHERE ScanAttachments(_Attachments,'vincent..'))
N MandN._fkContacts = _ID

so it doesn't get included in the "main" progress calculations.  It's
something that has needed to be addressed, but hasn't been yet.  It's
semi-difficult to pre-calculate the total progress when dealing with various
sub-queries, etc.

--
Tim Young
Elevate Software
www.elevatesoft.com

Tim


Fair enough.

On another topic any chance of OnFilterProgress in ElevateDB?

Roy Lambert

Roy,

<< On another topic any chance of OnFilterProgress in ElevateDB? >>

Yes, there certainly is a chance.

--
Tim Young
Elevate Software
www.elevatesoft.com