On 19-11-2011 23:36, Michael Van Canneyt wrote:
> On Sat, 19 Nov 2011, Reinier Olislagers wrote:
>> On 19-11-2011 13:28, Reinier Olislagers wrote: I wonder
>> whether/what changes are required for reading blobs...
>
> The following function needs adapting:
>
> function TIBConnection.getMaxBlobSize(blobHandle : TIsc_Blob_Handle)
> : longInt; var iscInfoBlobMaxSegment : byte =
> isc_info_blob_max_segment; blobInfo : array[0..50] of byte;
>
> begin if isc_blob_info(@Fstatus[0], @blobHandle,
> sizeof(iscInfoBlobMaxSegment), pchar(@iscInfoBlobMaxSegment),
> sizeof(blobInfo) CheckError('isc_blob_info', FStatus); if blobInfo[0]
> = isc_info_blob_max_segment then begin result :=
> isc_vax_integer(pchar(@blobInfo[3]),
> isc_vax_integer(pchar(@blobInfo[1]), 2)); end else
> CheckError('isc_blob_info', FStatus); end;
>
> You should first check what it returns. I suspect the declared blob
> segment size.
>
> Michael.
getMaxBlobSize does indeed return the segment size used when writing
(i.e. 80 by default on pre 2.7.1, 65535 with my patch).
Changed ibconnection.pp:
- remove getMaxBlobSize function
- use MAXBLOBSEGMENTSIZE (65535) when reading
Tested it with existing blobs written in 80 byte and 65535 byte
segments. Works; the returned value matches what was written in the
first place:
while FQuery.EOF=false do
begin
if FQuery.FieldByName('BLOBCOL').AsString <> RecordText then writeln
('Error reading record');;
FQuery.Next;
end;
Patch attached; it applies against 2.7.1.
Please let me know if you want me to open a bug for this...
Thanks,
Reinier
--- d:/cop/t/ibconnection.pp Sun Nov 20 10:20:53 2011
+++
C:/Development/Fpc/Source/packages/fcl-db/src/sqldb/interbase/ibconnection.pp
Sun Nov 20 10:23:10 2011
@@ -65,7 +65,6 @@
procedure GetFloat(CurrBuff, Buffer : pointer; Size : Byte);
procedure SetFloat(CurrBuff: pointer; Dbl: Double; Size: integer);
procedure CheckError(ProcName : string; Status : PISC_STATUS);
- function getMaxBlobSize(blobHandle : TIsc_Blob_Handle) : longInt;
procedure SetParameters(cursor : TSQLCursor; aTransation :
TSQLTransaction; AParams : TParams);
procedure FreeSQLDABuffer(var aSQLDA : PXSQLDA);
function IsDialectStored: boolean;
@@ -1249,22 +1248,6 @@
end;
-function TIBConnection.getMaxBlobSize(blobHandle : TIsc_Blob_Handle) : longInt;
-var
- iscInfoBlobMaxSegment : byte = isc_info_blob_max_segment;
- blobInfo : array[0..50] of byte;
-
-begin
- if isc_blob_info(@Fstatus[0], @blobHandle, sizeof(iscInfoBlobMaxSegment),
pchar(@iscInfoBlobMaxSegment), sizeof(blobInfo) - 2, pchar(@blobInfo[0])) <> 0
then
- CheckError('isc_blob_info', FStatus);
- if blobInfo[0] = isc_info_blob_max_segment then
- begin
- result := isc_vax_integer(pchar(@blobInfo[3]),
isc_vax_integer(pchar(@blobInfo[1]), 2));
- end
- else
- CheckError('isc_blob_info', FStatus);
-end;
-
procedure TIBConnection.LoadBlobIntoBuffer(FieldDef: TFieldDef;ABlobBuf:
PBufBlobField; cursor: TSQLCursor; ATransaction : TSQLTransaction);
const
isc_segstr_eof = 335544367; // It's not defined in ibase60 but in ibase40.
Would it be better to define in ibase60?
@@ -1273,7 +1256,6 @@
blobHandle : Isc_blob_Handle;
blobSegment : pointer;
blobSegLen : word;
- maxBlobSize : longInt;
TransactionHandle : pointer;
blobId : PISC_QUAD;
ptr : Pointer;
@@ -1286,14 +1268,13 @@
if isc_open_blob(@FStatus[0], @FSQLDatabaseHandle, @TransactionHandle,
@blobHandle, blobId) <> 0 then
CheckError('TIBConnection.CreateBlobStream', FStatus);
- maxBlobSize := getMaxBlobSize(blobHandle);
-
- blobSegment := AllocMem(maxBlobSize);
+ //For performance, read as much as we can, regardless of any segment size
set in database.
+ blobSegment := AllocMem(MAXBLOBSEGMENTSIZE);
with ABlobBuf^.BlobBuffer^ do
begin
Size := 0;
- while (isc_get_segment(@FStatus[0], @blobHandle, @blobSegLen, maxBlobSize,
blobSegment) = 0) do
+ while (isc_get_segment(@FStatus[0], @blobHandle, @blobSegLen,
MAXBLOBSEGMENTSIZE, blobSegment) = 0) do
begin
ReAllocMem(Buffer,Size+blobSegLen);
ptr := Buffer+Size;
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