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SAP Knowledge Base Article - PreviewSymptom
- During a Delta merge for certain large tables stored in NSE, the HANA system performance becomes degraded and even leads to blocked savepoints.
- Mini Checks report shows the following alerts:
|M0346| Long waitForLock savepoint phases (mid-term)| | 5| 0|X| 2100009|
|M0537| Tables with long total merge time (short-term)| | CDPOS (2.70 h)| none|X| 2057046|
|M0538| Long running delta merges (mid-term)| | CDPOS (18) (2067 s, 2026/04/14 17:42:46)| none|X| 2057046|
|M0538| Long running delta merges (mid-term)| | CDPOS (2) (2017 s, 2026/04/14 17:42:46)| none|X| 2057046|
|M0538| Long running delta merges (mid-term)| | DBTABLOG (6314 s, 2026/04/11 10:54:45)| none|X| 2057046|
|M2730| Columns with significant NSE buffer size share|hostname| DBTABLOG.LOGDATA (149 %)| none|X| 2799997|
|M2735| NSE buffer cache reloads (% per day, mid-term)|hostname| 134| <= 100|X| 2799997|
- Savepoint may be blocking the delta merge with a callstack like :
[SAVEPOINT_SHAREDLOCK_OWNERS] Owners of shared SavepointLocks: (2026-04-03 03:02:17 159 Local)
3275745778[thr=259052]: JobWrk109424, TID: 325, UTID: 2152546830, CID: -1, LCID: 0, SEID: 844434391012380, parent: 2434919, SQLUserName: "", AppUserName: "", AppName: "", ConnCtx: ---, StmtCtx: ---, WorkloadCtx: ---, NUMA node: 0, type: "JobWorker", method: "prepareDeltaMerge",
detail: "IndexName: SAPHANADB:BALDAT Attribute: 214/$trexexternalkey$", command: "" at 0x00007fe82b961131 in __clock_nanosleep_2+0x83 (libc.so.6)
[OK] in 00:00:00 003
--
3275745778[thr=259052]: JobWrk109424 at
0: 0x00007fe82b961131 in __clock_nanosleep_2+0x82 (libc.so.6)
1: 0x00007fe82b966e53 in __GI___nanosleep+0x12 (libc.so.6)
2: 0x00007fe82c6806bc in Execution::sleep(timespec&)+0xa8 at Basis/Execution/impl/Sleep.cpp:33 (libhdbbasis.so)
3: 0x00007fe82c680861 in Execution::milliSleep(unsigned long)+0x40 at Basis/Execution/impl/Sleep.cpp:60 (libhdbbasis.so)
4: 0x00007fe83209ca61 in BufferCacheManager::LogicalPageBufferCache::provideControlblockInternal(PageAccess::SizeClass, PageAccess::SizeClass, ResourceManager::ResourceContainer&, PageAccess::LogicalPageAccess&, unsigned long, PageAccess::PageNo const&, ResourceManager::Disposition, PageAccess::ConverterPageControlBlock*, DAEncryption::EncryptionManager*, bool, Synchronization::ReadWriteLockStatistics*, bool)+0x540 at NDS/BufferCache/impl/BufferCache.cpp:464 (libhdbnds.so)
5: 0x00007fe82f07c5d5 in PageAccess::LogicalPageResourceProvider::provideControlblock(PageAccess::SizeClass, PageAccess::SizeClass, ResourceManager::ResourceContainer&, PageAccess::LogicalPageAccess&, unsigned long, PageAccess::PageNo const&, ResourceManager::Disposition, PageAccess::ConverterPageControlBlock*, DAEncryption::EncryptionManager*, bool, Synchronization::ReadWriteLockStatistics*, bool)+0x121 at DataAccess/PageAccess/impl/LogicalPageResourceProviderImpl.cpp:176 (libhdbdataaccess.so)
6: 0x00007fe82f06aa95 in PageAccess::LogicalPageAccessImpl::providePreliminaryPage(DataContainer::ContainerID const&, PageAccess::PageType, PageAccess::SizeClass, PageAccess::LogicalPageResourceProvider&, bool)+0x331 at DataAccess/PageAccess/impl/LogicalPageAccessImpl.cpp:943 (libhdbdataaccess.so)
7: 0x00007fe82f06d2bc in PageAccess::LogicalPageAccessImpl::allocatePage(DataContainer::ContainerID const&, PageAccess::PageType, PageAccess::SizeClass, ResourceManager::Disposition, PageAccess::LogicalPageResourceProvider&, bool)+0x48 at DataAccess/PageAccess/impl/LogicalPageAccessImpl.cpp:1188 (libhdbdataaccess.so)
8: 0x00007fe82f06d484 in PageAccess::LogicalPageAccess::allocatePage(DataContainer::ContainerID const&, PageAccess::PageType, PageAccess::SizeClass, ResourceManager::Disposition, PageAccess::LogicalPageResourceProvider&, bool)+0x10 at DataAccess/PageAccess/impl/LogicalPageAccessImpl.cpp:368 (libhdbdataaccess.so)
9: 0x00007fe82edfd7d0 in DataContainer::ContainerImpl::allocatePage(PageAccess::PageType, PageAccess::SizeClass, ResourceManager::Disposition, PageAccess::LogicalPageResourceProvider&, bool) const+0x60 at DataAccess/DataContainer/impl/ContainerImpl.cpp:929 (libhdbdataaccess.so)
10: 0x00007fe83285a466 in UnifiedTable::BufferedPageChain::allocatePage(PageAccess::PageType, PageAccess::SizeClass, ResourceManager::Disposition)+0x162 at UnifiedTable/Paging/impl/PageChain.cpp:1452 (libhdbunifiedtable.so)
11: 0x00007fe832875cc4 in UnifiedTable::DictionaryPagedBlockProvider::newPageSpanningDictBlock(ltt::versioned_gc_queue&, UnifiedTable::PersDictionaryDescriptor const&, PageAccess::SizeClass, bool, UnifiedTable::DictionaryHeaderInit const&)::{lambda(ResourceManager::Disposition)#1}::operator()(ResourceManager::Disposition) const+0x40 at UnifiedTable/Paging/impl/PagedDictionaryBlockHandler.cpp:401 (libhdbunifiedtable.so)
12: 0x00007fe8328768a0 in UnifiedTable::DictionaryPagedBlockProvider::newPageSpanningDictBlock(ltt::versioned_gc_queue&, UnifiedTable::PersDictionaryDescriptor const&, PageAccess::SizeClass, bool, UnifiedTable::DictionaryHeaderInit const&)+0x3e0 at UnifiedTable/Paging/impl/PagedDictionaryBlockHandler.cpp:473 (libhdbunifiedtable.so)
13: 0x00007fe8328769c4 in UnifiedTable::DictionaryPagedBlockProvider::newPageSpanningDictBlock(ltt::versioned_gc_queue&, UnifiedTable::PersDictionaryDescriptor const&, PageAccess::SizeClass, UnifiedTable::DictionaryHeaderInit const&)+0x10 at UnifiedTable/Paging/impl/PagedDictionaryBlockHandler.cpp:364 (libhdbunifiedtable.so)
14: 0x00007fe8325f6a9f in UnifiedTable::PagedDictionaryBlockHandler::newPageSpanningDictBlock(ltt::versioned_gc_queue&, PageAccess::SizeClass, UnifiedTable::DictionaryHeaderInit const&)+0x6b at UnifiedTable/Paging/spi/DictionaryPagedBlockProvider.hpp:578 (libhdbunifiedtable.so)
15: 0x00007fe832662287 in UnifiedTable::MainVarDictionaryStorageBase::getNewDictionaryBlock(PageAccess::SizeClass)+0x43 at UnifiedTable/Dictionary/impl/MainVarDictionaryStorage.cpp:824 (libhdbunifiedtable.so)
16: 0x00007fe83266a839 in UnifiedTable::MainVarDictionaryStorageBase::sortedAddImpl(DataAccess::ConsistentChange&, void const*, unsigned long, PageAccess::SizeClass)+0x385 at UnifiedTable/Dictionary/impl/MainVarDictionaryStorage.cpp:1396 (libhdbunifiedtable.so)
17: 0x00007fe83cb04893 in AttributeEngine::RoDict<TRexUtils::CESU8>::sortedAdd(AttributeEngine::DictionaryModificationGuard&, char const*, unsigned long, int)+0x50 at AttributeEngine/Main/Dictionary/RoDictUnified.cpp:2181 (libhdbcs.so)
18: 0x00007fe83c318d9c in AttributeEngine::DeltaMerge::CreateDictionaryStep<TrexTypes::StringAttributeValue, AttributeEngine::ValueDict<TrexTypes::StringAttributeValue>, AttributeEngine::BTreeAttribute<TrexTypes::StringAttributeValue> >::doStepImpl()+0x798 at AttributeEngine/Main/Dictionary/StringDict.h:240 (libhdbcs.so)
19: 0x00007fe83c37aabc in AttributeEngine::DeltaMerge::SingleMergePipeline<TrexTypes::StringAttributeValue, AttributeEngine::ValueDict<TrexTypes::StringAttributeValue>, AttributeEngine::BTreeAttribute<TrexTypes::StringAttributeValue>, NDS::Primitives::PagedIndexVector>::merge(AttributeEngine::BTreeAttribute<TrexTypes::StringAttributeValue> const&, AttributeEngine::DeltaMerge::AttributeMergeData&, AttributeEngine::ValueDict<TrexTypes::StringAttributeValue>&, AttributeEngine::DeltaMerge::PrepareNewDictCallback<AttributeEngine::ValueDict<TrexTypes::StringAttributeValue> >&, NDS::Primitives::PagedIndexVector&, unsigned long&)+0x348 at AttributeEngine/DeltaMerge/SingleMergePipeline.cpp:164 (libhdbcs.so)
20: 0x00007fe83d35a472 in AttributeEngine::PagedAttribute<TrexTypes::StringAttributeValue, AttributeEngine::ValueDict<TrexTypes::StringAttributeValue> >::mergeOldIntoNew(AttributeEngine::AttributeValueContainer const&, AttributeEngine::DeltaMerge::AttributeMergeData&)+0x2b0 at AttributeEngine/Main/PagedAttributeDef.h:4472 (libhdbcs.so)
21: 0x00007fe841ffd122 in AttributeEngine::MemoryAvc2::prepareDeltaMerge(AttributeEngine::AttributeValueContainer&, AttributeEngine::DeltaMerge::AttributeMergeData&)+0xa0 at AttributeEngine/AttributeValueContainer.cpp:3139 (libhdbcs.so)
22: 0x00007fe841dba59b in AttributeEngine::AttributeApi::prepareDeltaMerge(TrexBase::IndexName const&, AttributeEngine::DeltaMerge::AttributeMergeData&)+0x627 at AttributeEngine/AttributeApi.cpp:1656 (libhdbcs.so)
23: 0x00007fe85265504c in TRexAPI::MergeAttributeJob::doMerge(TRexAPI::ColumnMergeData&, TRexAPI::DeltaMergeState&, bool)+0x48 at ims_search_api/DeltaMerge/MergeAttributeJob.cpp:176 (libhdbcsapi.so)
24: 0x00007fe852655b0f in TRexAPI::MergeAttributeJob::run(Execution::Context&, Execution::JobObject&)+0x19b at ims_search_api/DeltaMerge/MergeAttributeJob.cpp:293 (libhdbcsapi.so)
25: 0x00007fe82c6335ea in Execution::JobObjectImpl::run(Execution::JobWorker*)+0x1416 at Basis/Execution/impl/JobExecutorRunJob.cpp:772 (libhdbbasis.so)
26: 0x00007fe82c63528a in Execution::JobWorker::runJob(ltt::smartptr_handle<Execution::JobObjectForHandle>&)+0x896 at Basis/Execution/impl/JobExecutorThreads.cpp:379 (libhdbbasis.so)
27: 0x00007fe82c636678 in Execution::JobWorker::run(Execution::ThreadRC&)+0x734 at Basis/Execution/impl/JobExecutorThreads.cpp:1382 (libhdbbasis.so)
28: 0x00007fe82c681ec1 in Execution::Thread::staticMainImp(Execution::Thread*)+0x5e0 at Basis/Execution/impl/Thread.cpp:605 (libhdbbasis.so)
29: 0x00007fe82c68275f in Execution::pthreadFunctionWrapper(Execution::Thread*)+0x1eb at Basis/Execution/impl/ThreadInterposition.cpp:691 (libhdbbasis.so)
30: 0x00007fe82d9806da in start_thread+0xd8 (libpthread.so.0)
31: 0x00007fe82b99d53f in __GI___clone+0x3d (libc.so.6)
- The NSE Buffer cache details show that CDPOS and DBTABLOG are much larger than the max buffer cache size (MAX_SIZE_GB) and thus prone to reloads between NSE cache in memory and persistence (PAGED_GB vs BUFF_GB).
HANA_NSE_BufferCache_*
HANA_NSE_BufferCache_Tables_*
HANA_Memory_Overview_*
------------------------------------------------------------------------------------------------------------------------------------------------
| SNAPSHOT_TIME|ST| HOST| PORT|WARM_GB|MAX_SIZE_GB|ALLOC_GB|USED_GB|IO_SIZE_GB|HIT_PCT|BUFF_KB|BUFF_TOT_GB|BUFF_HOT_GB|BUFF_FREE_GB|
------------------------------------------------------------------------------------------------------------------------------------------------
|2026/04/15 14:24:46| 0|Hostname|30440| 718.45| 146.48| 146.48| 133.83| 377816.46| 99.26| 4| 0.00| 0.00| 0.00|
| | | | | | | | | | | 16| 0.00| 0.00| 0.00|
| | | | | | | | | | | 64| 0.01| 0.01| 0.00|
| | | | | | | | | | | 256| 131.07| 130.13| 0.88|
| | | | | | | | | | | 1024| 14.95| 1.05| 11.75|
------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
| HOST| PORT|TOT_BUFF_GB|SCHEMA_NAME| TABLE_NAME|PAGED_GB|BUFF_GB|BUFF_PCT|USED_PCT|
------------------------------------------------------------------------------------------------
|Hostname|30440| 146.48| SAPHANADB| CDPOS| 392.29| 111.80| 28.50| 76.32|
|Hostname|30440| 146.48| SAPHANADB| DBTABLOG| 281.53| 15.68| 5.57| 10.71|
|Hostname|30440| 146.48| SAPHANADB| BALDAT| 32.95| 1.81| 5.51| 1.24|
|Hostname|30440| 146.48| SAPHANADB| D010TAB| 1.54| 0.82| 53.77| 0.56|
|Hostname|30440| 146.48| SAPHANADB| D010INC| 0.76| 0.76| 99.85| 0.52|
------------------------------------------------------------------------------------------------------------------------------------------------
| NAME|TOTAL_GB| DETAIL_GB| DETAIL2_GB|
------------------------------------------------------------------------------------------------------------------------------------------------
| | | | |
| Column store size| 999| 999 (Hostname)| 120 (CDPOS)|
| | | | 80 (ACDOCA)|
| | | | 75 (PRCD_ELEMENTS)|
| | | | 40 (BSEG)|
| | | | 37 (CDHDR)|
| | | | 29 (FAGL_SPLINFO_VAL)|
| | | | 29 (ACCTCR)|
| | | | 22 (JCDS)|
| | | | 21 (OBJK)|
| | | | 17 (BSAS_BCK)|
| | | | |
| | | | |
| NSE table size| 134| 134 (Hostname)| 112 (CDPOS)|
| | | | 16 (DBTABLOG)|
| | | | 2 (BALDAT)|
| | | | 1 (D010TAB)|
| | | | 1 (D010INC)|
| | | | 1 (DD03L)|
| | | | |
| Disk size| 4094| 4094 (global)| 1003 (SOFFCONT1)|
| | | | 502 (DBTABLOG)|
| | | | 399 (CDPOS)|
| | | | 243 (DHCDC_RTSTORE)|
| | | | 145 (GRACSODREPDATA)|
| | | | 138 (ZTPL_POD_LOG1)|
| | | | 138 (ZTPL_POD_LOG)|
| | | | 117 (ZGDM_POD_LOG1)|
| | | | 76 (ACDOCA)|
| | | | 74 (PRCD_ELEMENTS)|
------------------------------------------------------------------------------------------------------------------------------------------------
Read more...
Environment
SAP HANA Platform Edition 2.0
Keywords
KBA , HAN-DB-NSE , SAP HANA Native Storage Extension , Problem
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