#1 2020-06-01 13:22:18

ASiwon
Member
From: Poland
Registered: 2015-01-30
Posts: 82

Problem with saving date values to the Oracle in batch mode.

Hi,

I'm using mORMot with Oracle database connected via SynDbOracle. Few days ago I decided to change my process to use batch mode to improve the performance.

After changing the code to use batch mode the program has started to reports databases constraints rules violation for columns with date values. But they occurs only when the Oracle database is used. For SQLite database everything works perfectly.

After long investigation I found the reason. Here is a little long explanation.
In SynDBOracle unit to the execution of queries the procedure ExecutePrepared is used. Here is the piece of code which is used to set date values to the query params:

          for j := 0 to fParamsArrayCount-1 do
            if VArray[j]='null' then // bind null (ftUTF8 should be '"null"')
              aIndicator[i][j] := -1 else begin
              if VDBType=SQLT_INT then
                SetInt64(pointer(Varray[j]),oDataINT^[j]) else
              case VType of
              ftUTF8,ftDate: begin
                L := length(VArray[j])-2; // -2 since quotes will be removed
                if VType=ftDate then
                  if L<=0 then
                    oDataDAT^[j].From(0) else
                    oDataDAT^[j].From(PUTF8Char(pointer(VArray[j]))+1,L) else      <--- Here is the date conversion command
                  if L>oLength then
                    if L*fParamsArrayCount>MAX_INLINED_PARAM_SIZE then
                      raise ESQLDBOracle.CreateUTF8(
                        '%.ExecutePrepared: Array parameter #% STR too big',[self,i+1]) else
                      oLength := L;
              end;

this code runs procedure TOracleDate.From to read date value from the JSON string to the TOracleDate record. In procedure From is used function: Iso8601ToTimeLogPUTF8Char which not always works correctly in this place.

procedure TOracleDate.From(aIso8601: PUTF8Char; Length: integer);
var Value: QWord;
    Value32: cardinal absolute Value;
    Y: cardinal;
    NoTime: boolean;
begin
  PInteger(PtrUInt(@self)+3)^ := 0; // set Day=Hour=Min=Sec to 0
  Value := Iso8601ToTimeLogPUTF8Char(aIso8601,Length,@NoTime);
  if Value=0 then begin
    PInteger(@self)^ := 0;
    exit; // invalid ISO-8601 text -> store as null date
  end;
...

It is because the Iso8601ToTimeLogPUTF8Char function expects date value in format: 2000-01-01 but in this case to the function is passed string from JSON format and it has single quote char
on the end of the string. The string with date looks like: 2000-01-01'. The function expects that after date part will be started time part or the end of the string.
When the function finds single quote char it stops the execution and returns 0. This causes the function for any date string returns value 0 and all these wrong values are saved to the database.

For my purposes I have change the Iso8601ToTimeLogPUTF8Char function code:

function Iso8601ToTimeLogPUTF8Char(P: PUTF8Char; L: integer; ContainsNoTime: PBoolean): TTimeLog;
// bits: S=0..5 M=6..11 H=12..16 D=17..21 M=22..25 Y=26..40
// i.e. S<64 M<64 H<32 D<32 M<16 Y<9999: power of 2 -> use fast shl/shr
var V,B: PtrUInt;
    tab: {$ifdef CPUX86NOTPIC}TNormTableByte absolute ConvertHexToBin{$else}PNormTableByte{$endif};
begin
  result := 0;
  if P=nil then
    exit;
  if L=0 then
    L := StrLen(P);
  if L<4 then
    exit; // we need 'YYYY' at least
  if P[0]='T' then
    dec(P,8) else begin // 'YYYY' -> year decode
    {$ifndef CPUX86NOTPIC}tab := @ConvertHexToBin;{$endif} // faster on PIC/x86_64
    V := tab[ord(P[0])];
    if V>9 then exit;
    B := tab[ord(P[1])];
    if B>9 then exit else V := V*10+B;
    B := tab[ord(P[2])];
    if B>9 then exit else V := V*10+B;
    B := tab[ord(P[3])];
    if B>9 then exit else V := V*10+B;
    result := Int64(V) shl 26;  // store YYYY
    if P[4] in ['-','/'] then begin inc(P); dec(L); end; // allow YYYY-MM-DD
    if L>=6 then begin // YYYYMM
      V := ord(P[4])*10+ord(P[5])-(48+480+1); // Month 1..12 -> 0..11
      if V<=11 then
        inc(result,V shl 22) else begin
        result := 0;
        exit;
      end;
      if P[6] in ['-','/'] then begin inc(P); dec(L); end; // allow YYYY-MM-DD
      if L>=8 then begin  // YYYYMMDD
        V := ord(P[6])*10+ord(P[7])-(48+480+1); // Day 1..31 -> 0..30
        if (V<=30) and(P[8] in [#0,' ','T', '''']) then  <-- here is single quote exception added.

after this change date values are correctly saved to the database. I could add this correction to the pull request, but I'm not sure is it the best place to make correction for this problem.


best regards
Adam Siwon

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#2 2020-06-01 13:46:41

ab
Administrator
From: France
Registered: 2010-06-21
Posts: 14,316
Website

Re: Problem with saving date values to the Oracle in batch mode.

I guess https://synopse.info/fossil/info/b28bbab8c9 is more correct.
Thanks for the feedback.

But please follow the forum rules, and don't put such an amount of code within the thread itself.

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