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#1 2018-07-29 04:01:50
- steve888
- Member
- Registered: 2018-07-17
- Posts: 8
FetchAllToBinary - Too Many Columns
I'm having a problem with a stored procedure that returns 300+ columns. FetchAllToBinary throws a 'Too Many Columns' exception. Unfortunately I'm unable to modify the procedure to return less columns. Any suggestions?
FillChar(Null,sizeof(Null),0);
result := 0;
W := TFileBufferWriter.Create(Dest);
try
W.WriteVarUInt32(FETCHALLTOBINARY_MAGIC);
FMax := ColumnCount;
W.WriteVarUInt32(FMax);
if FMax>0 then begin
// write column description
SetLength(ColTypes,FMax);
dec(FMax);
for F := 0 to FMax do begin
W.Write(ColumnName(F));
ColTypes[F] := ColumnType(F,@FieldSize);
W.Write1(ord(ColTypes[F]));
W.WriteVarUInt32(FieldSize);
end;
// initialize null handling
NullRowSize := (FMax shr 3)+1;
if NullRowSize>sizeof(Null) then <-------------------------
raise ESQLDBException.CreateUTF8(
'%.FetchAllToBinary: too many columns',[self]);
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#3 2018-07-30 22:01:45
- steve888
- Member
- Registered: 2018-07-17
- Posts: 8
Re: FetchAllToBinary - Too Many Columns
Sadly it is hardcoded...
Yes, TSqlDbProxyStatementColumns is a set limited to 256 elements. Changing this to an array is a way around this limit.
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#4 2018-09-13 08:48:59
- cybexr
- Member
- Registered: 2016-09-14
- Posts: 81
Re: FetchAllToBinary - Too Many Columns
Meet same problem here, Syndb support fetch unlimted columns, but this FetchAllToBinary break the completeness.
And FetchAllToJSON() will loose ColumnValueDBSize (original DBMS declared fieldsize ) information , FetchAllToBinary is the only way in my enviorment. hope it will be corrected.
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#5 2019-05-16 19:19:18
- fbkopp
- Member
- Registered: 2017-08-11
- Posts: 4
Re: FetchAllToBinary - Too Many Columns
I have hit same limit for a table with more than 256 columns, will there be a change or correction for the hard coded limit?
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#6 2019-05-17 12:57:38
Re: FetchAllToBinary - Too Many Columns
256 columns is already too much! Time for DB refactoring! 
See https://dba.stackexchange.com/a/3976
But anyway, since most SQL DB allows up to 1000 columns per table - with performance impact for sure - I allowed any column count limit for SynDB remote binary serialization. 
See https://synopse.info/fossil/info/3fb2ed0db6
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#7 2019-05-20 14:42:54
- fbkopp
- Member
- Registered: 2017-08-11
- Posts: 4
Re: FetchAllToBinary - Too Many Columns
Thank you very much, it worked perfectly. Tested with 260 columns.
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