2574686 - A "main Bufman: Blockmap info error" error happened just after starting a DELETE statement.

1. "slib/s_blockmap.cxx:11424" and "slib/s_ohcidx.cxx:7424" error happened as below as soon as the DELETE statement got started.

No stacktrace for this error generated in the IQ message log.

=,<,15669,PREPARE,delete from "OWNER001"."TAB001" where("COL001" < "DATEFORMAT"("DAYS"("DATE"('2000101),-2),'YYYYMMDD') or "LOAD_DT" = '20001231')
+202,E,15669,-1006000,IQ Internal error. Please report this to SAP IQ support. -- (slib/s_blockmap.cxx 7006)

I. 11/30 16:48:23. 0000064027 [20917]: Delete of 1401759 rows started for table:
I. 11/30 16:48:24. 0000064027 main Bufman: Blockmap info error; bmp={bl=1849853998566942,uid=70522307,txn=40090637,sp=1737,nentr=1692,rb=54519858,nlnk=2,flags=0xd,...........
I. 11/30 16:48:24. 0000064027 =13,rmod=13}. slib/s_blockmap.cxx:11424
I. 11/30 16:48:24. 0000064027 The following exception is from GetBlockmapEntryInfo
I. 11/30 16:48:24. 0000064027 Blockmap Member Variables for 0x7fb5210dd718
I. 11/30 16:48:24. 0000064027 From slib/s_ohcidx.cxx:7424
I. 11/30 16:48:24. 0000064027 _nextPartitionForHelperFlush = 0
...................
...................
I. 11/30 16:48:24. 0000064027 GetBlockmapEntryInfo() Inputs & Outputs:
I. 11/30 16:48:24. 0000064027 logicalBlockId: 0
I. 11/30 16:48:24. 0000064027 link: 1849853998566942
I. 11/30 16:48:24. 0000064027 serverID: 0
I. 11/30 16:48:24. 0000064027 Exception Thrown from slib/s_blockmap.cxx:7006, Err# 0, tid 1010 origtid 1010
I. 11/30 16:48:24. 0000064027 O/S Err#: 0, ErrID: 2092 (s_invalidinputexception); SQLCode: -1006000, SQLState: 'QBA00', Severity: 23

2. This error happened at IQ 16.0 SP11 PL06, but the same error occurred again after upgrading the IQ database to SP11 PL12.
3. DBCC (with check and verify options) did not report any error.
   
   I. 11/30 16:48:09. 0000064027 DBCC Verify Mode Report:
   I. 11/30 16:48:09. 0000064027 DBCC Status: No Errors Detected

4. There exists ONE unique HG index.

SAP IQ 16.0 SP11

SAP IQ, IQ, slib/s_blockmap.cxx:11424, slib/s_ohcidx.cxx:7424, s_blockmap, s_ohcidx, main Bufman, Blockmap info error, GetBlockmapEntryInfo, CR812208, CR#812208, CR 812208, CR820361, CR#820361, CR 820361, , KBA , BC-SYB-IQ , Sybase IQ , Bug Filed