2584562 - IQ 16.0 server became crash when touching the inconsistent FP index

While running DMLs, server encountered inconsistency on a FP index and following errors were appeared when touching the problematic table.

• main Bufman: Decompression error during Read; from slib/s_buf.cxx:1787

• Exception Thrown from slib/s_blockmap.cxx:6578, Err# 0, tid 1519 origtid 1519
  OS Err#: 0, ErrID: 2099 (s_decompressionexception); SQLCode: -1009046, SQLState: 'QSA46', Severity: 14
  [20067]:main Bufman: An error was detected on a database page. You may have a damaged index. For additional information, please check your IQ message file or run sp_iqcheckdb.
  -- (slib/s_blockmap.cxx 6578)

• slib/s_barray.cxx:11274 - get_suc 0, 0, 201326593 
  ********************************************************
  **
  ** Non-Fatal IQ Internal Error Detected
  ** at slib/s_barray.cxx:11276 on thread xxxxxxxxxxxxxxx (TID xxxx)
  ..
  call "<user_name>"."procedure_name"()
  ...
  ===== Thread Number xxxxxxxxxxxxxxx (IQ connID: 000000xxxx) =====
  pcstkwalk(stk_trace*, int, db_log*, hos_fd*)+0x32
  ucstkgentrace(int, int)+0x121
  StackTraceForThisThread(char const*, int, char const*, char const*, char const*)+0x314
  s_mergeFINALWriter::CompletePage()+0x368
  s_mergeFINALWriter::Complete()+0x4c
  hs_dpInsert::FinishedInsert()+0x3b
  dfiio_FP::FinishedInsert()+0x33
  dfo_IndexInsert::FinalFetchOpus()+0x182
  dfo::FinalFetch()+0x50
  ..

• main Bufman: Incorrect page header read; from slib/s_trycatch.cxx:2928
  expected: btype=14,pbn=26814140308,txn=202842106,sp=16854,nlb=16,npb=16,iscmp=0,uid=172697817,blk=26814140308,mn=67,upmn=67,flgs=0x80000000
  head: btype=13,pbn=26814140308,txn=184235841,sp=354,nlb=16,npb=10,iscmp=1,ctr=136,cta=135,ver=2,pb=197,pus=43428
  buffer: 0x0d0010000a008887944f3f3e060000004137fb0a000000006201000002c5a4a9
  Expected Pad1: 148 (0x94), Pad2: 10457 (0x28d9)
  Got Pad1: 197 (0xc5), Pad2: 43428 (0xa9a4)
  There was an s_buf::Read() error during s_bufman::Find().
  ..
  **************************************************
  *** SAP IQ Abort:
  *** From: slib/s_blockmap.cxx:1271
  *** PID: xxxxxxx
  ..
  ===== Thread Number xxxxxxxxxxxxxxx (IQ connID: 000000xxxx) =====
  pcstkwalk(stk_trace*, int, db_log*, hos_fd*)+0x32
  ucstkgentrace(int, int)+0x121
  DumpAllThreads(char const*, unsigned int, int)+0x259
  hos_ABORT(char const*, unsigned int, char const*, char*, char*)+0x26a
  s_blockmap::~s_blockmap()+0x141
  s_VersioningBlockmap::~s_VersioningBlockmap()+0x2a
  s_bufman::Rollback(unsigned long long, unsigned int, int)+0x2a0
  st_txncb::Rollback()+0x462
  st_txnMgr::Rollback()+0x174
  st_command::DoCmdThroughResourceGate()+0x82
  st_iqtxn::RollbackTxn(UIConnection*)+0x23
  UIQTxn_RollbackTxn+0x15
  st_SAIQInterfaceInfo::callFunction()+0x26
  st_SAIQInterface::RunIQFunc(st_SAIQInterfaceInfo*)+0x1ac
  st_SAIQInterface::Execute(int, void*, unsigned int (*)+0x20a
  saint_iqthresholdtxn::RollbackTxn(IConnection*)+0xbd
  DB_Rollback_Chgs(Connection*)+0x231
  ..

• DBCC with verify mode report inconsistent index error:
  (DBA)> sp_iqcheckdb 'verify table user_name.table_name';
  ..
  DBCC Verify Mode Report
  ================================================== ============================== ======
  ** DBCC Status Errors Detected ******
  DBCC Status Free list duplicates checking skipped on secondary server
  ** DBCC Decompress Errors 1 ******
  ..
  Index Statistics
  ================================================== ============================== ======
  ** Inconsistent Index user_name.FP_index_name
  ** Non-Completed Index user_name.FP_index_name ******

SAP IQ 16.0 SP11 PL09

KBA , BC-SYB-IQ , Sybase IQ , Problem