16.20 - C Function Definition - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL External Routine Programming

Product
Advanced SQL Engine
Teradata Database
Release Number
16.20
Release Date
April 2020
Content Type
Programming Reference
Publication ID
B035-1147-162K
Language
English (United States)
#define SQL_TEXT Unicode_Text
#include "sqltypes_td.h"
#include <string.h>
#define buffer_size 64000

void dclobcompress(UDT_HANDLE*         inputUDT,
                   LOB_RESULT_LOCATOR* resultLobLoc,
                   char                sqlstate[6] )
{
   LOB_LOCATOR sourceLobLoc;
   BYTE inputBuffer[buffer_size];
   BYTE outputBuffer[buffer_size];
   LOB_CONTEXT_ID id;
   FNC_LobLength_t readlen, writelen;
   int trunc_err = 0;
   readlen = 0;
   writelen = 0;

   FNC_GetDistinctInputLob(*inputUDT,&sourceLobLoc);
   FNC_LobOpen(sourceLobLoc, &id, 0, 0);

   while( FNC_LobRead(id, inputBuffer, buffer_size, &readlen) == 0 && !trunc_err )
   {
      /* Perform compression on the buffer (remove extra bytes)*/
      BYTE *inputPtr = inputBuffer;
      BYTE *outputPtr = outputBuffer;
      int i=0;
      for (i=0; i<(readlen/2); i++){
         memcpy(outputPtr,inputPtr,sizeof(BYTE));
         inputPtr += sizeof(BYTE);
         if (*inputPtr != 0)
         {
            strcpy(sqlstate,"38000",5);
            return;
         }
         inputPtr += sizeof(BYTE);

         outputPtr += sizeof(BYTE);
      }
      trunc_err = FNC_LobAppend(*resultLobLoc, outputBuffer, (readlen/2), &writelen);

      /* check trunc_err and properly report an error (performed in the same way as for
      a standard UDF) */
   }
   FNC_LobClose(id);
}