1996092 - [SAP IQ] When running a select statement having a case expression, IQ server get crashed with "s_blockmap.cxx:2988" and "s_buf.cxx:656" error.

1. When running a select statement below having a case expression, IQ server get crashed with "s_blockmap.cxx:2988" and "s_buf.cxx:656" error.
2. Problematic sql
• select  k.COL001
   from  TAB001 k
   where  k.COL002  in ('11111,'11112','11113','11114')
   and case when k.COL003 <> '2' then (case when k.COL004 = '0000' then '0001' else k.COL004  end)
     else k.COL004  end > '0000' ;
3. No error detected from DBCC against the table referenced by the problematic sql.
4. Error Message

• ********************************************************
  **
  **       Non-Fatal IQ Internal Error Detected
  **       at s_blockmap.cxx:2988  on thread 396301 (TID 1542)
  .............................................................................................................................................
  .............................................................................................................................................

  pc: 0x9000000023f1e48 .pcstkwalk(.............................................
  pc: 0x9000000023f18a8 .ucstkgentrace(.............................................
  pc: 0x9000000023f2288 .StackTraceForThisThread(.............................................
  pc: 0x9000000027fd614 .s_bufman_exception::s_bufman_exception(.............................................
  pc: 0x900000002216ca4 .s_blockmap::GetBlockmapEntryInfo(.............................................
  pc: 0x90000000221cf88 .s_blockmap::Find(.............................................
  pc: 0x900000002bd8170 .s_dpByteFetch::FindBuf(.............................................
  .............................................................................................................................................
  .............................................................................................................................................
  **
  **       End of stack trace from Non-Fatal IQ Internal Error s_blockmap.cxx:2988
  **
  ********************************************************
     
  Exception Thrown from s_blockmap.cxx:2988, Err# 8, tid 1542 origtid 1542
     O/S Err#: 0, ErrID: 2055 (s_bufman_exception); SQLCode: -1009047, SQLState: 'QSA47', Severity: 14
  [20068]: main Bufman: Blockmap info error; bmp={bl=4,uid=1170416,txn=6887842,sp=33,nentr=1,rb=1853493345,nlnk=1,flags=0xd,vsn=1,fan=8,flags2=0x0,nper=14348,fa=0,max=1}.
  Internal error: Unlocking a Buffer that is not locked.
  .............................................................................................................................................
  .............................................................................................................................................
   
  **************************************************
  ***   Sybase IQ Abort:
  ***      From:  s_buf.cxx:656
  ***      PID: 6029456
  ***      Exception Location: 0x11cd49500
  ***      Error ID: 533,  Exception Type: hos_assertexception
  ***      Thread: 27757  (TID: 7, Original TID: 7)
  ***      Error #: 3,  O/S Error #: 0
  **************************************************
  .............................................................................................................................................
  .............................................................................................................................................

  ===== Thread Number  27757  (IQ connID: 0000211817) =====

  pc: 0x9000000023f1e48 .pcstkwalk(.............................................
  pc: 0x9000000023f18a8 .ucstkgentrace(.............................................
  pc: 0x9000000023f0294 .DumpAllThreads(.............................................
  pc: 0x9000000020d99c0 .hos_ABORT(.............................................
  pc: 0x9000000020e512c .ThrowAbort(.............................................
  pc: 0x9000000020e4e50 .Throw(.............................................
  pc: 0x9000000020a6810 .hos_assertexception::ThrowException(.............................................
  pc: 0x9000000027ea724 .s_buf::UnlockUserLocked(.............................................
  pc: 0x9000000027ea44c .s_buf::UnlockUser(.............................................
  pc: 0x900000002bd0b88 .s_dpByteFetch::~s_dpByteFetch()+.............................................
  pc: 0x900000002bd8ca8 .s_dpByteStore::CloseFetch(.............................................

• SAP SYBASE IQ 15.3 & 15.4

s_blockmap.cxx:2988,  s_buf.cxx:656, CR 691261 , , KBA , BC-SYB-IQ , Sybase IQ , Problem