PAGEIOLATCH_EX

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Description:

This wait type is when a thread is waiting for the read of a data file page from disk to complete, and the thread is going to modify the page structure once it is in memory (EX = EXclusive mode). The Latches Whitepaper in the sidebar on the right has a description of all latch modes and their compatibility with other latch modes.

(Books Online description: “Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Exclusive mode. Long waits may indicate problems with the disk subsystem.”)

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Added in SQL Server version:

Pre-2005/2005

Removed in SQL Server version:

N/A

Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 68 in all versions through 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.

Other information:

See the PAGEIOLATCH_SH wait type for more details.

Known occurrences in SQL Server (list number matches call stack list):

1. Reading a page from disk so that ghost records can be removed from it
2. Reading a page from disk so a row can be inserted on it (in this case, a row being inserted into a system table as part of creating a table)
3. Reading a file header page from disk before changing it (in this case, as part of growing a file to allow a new extent to be allocated during a bulk load of data into a heap)

And many more similar stacks where rows are being inserted, updated, or deleted.

Abbreviated call stacks (list number matches known occurrences list):

1. SOS_Task::PostWait+90
   EventInternal::Wait+1f9
   LatchBase::Suspend+633
   LatchBase::AcquireInternal+415
   BUF::AcquireLatch+78
   GhostExorciser::GetNextGhostPageInPFS+104
   GhostExorciser::GetNextGhostedPage+7a
   TaskGhostCleanup::ProcessTskPkt+51d
   GhostRecordCleanupTask+10b
   CGhostCleanupTask::ProcessTskPkt+9
   TaskReqPktTimer::ExecuteTask+63
   OnDemandTaskContext::ProcessTskPkt+285
   SystemTaskEntryPoint+431
   OnDemandTaskContext::FuncEntryPoint+25
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+a8
2. SOS_Task::PostWait+90
   EventInternal::Wait+1f9
   LatchBase::Suspend+633
   LatchBase::AcquireInternal+415
   BUF::AcquireLatch+78
   BPool::Get+ea
   IndexPageManager::GetPageWithKey+1206
   IndexDataSetSession::LocatePageForInsert+202
   IndexDataSetSession::InsertSmallRecord+dac
   IndexDataSetSession::InsertRowInternal+2d11
   DatasetSession::InsertRow+163
   RowsetNewSS::InsertRow+26
   CMEDScanBase::FInsertSingle+9c
   CMEDScan::FInsertRow+462
   ECatBitsYukon::FInsertObjRow+1f6
   CMEDCatYukonObject::FPersistObjectInCatalog+5bb
   CMEDCatalogObject::FPersistObject+132
   CMEDProxySchema::CreateObject+167
   CTableCreate::LCreateImpl+c86
   CStmtCreateTable::XretCreateTableExecute+1c0
   CXStmtCreateTableDDL::XretExecute+3b
   CMsqlExecContext::ExecuteStmts<1,1>+400
3. SOS_Task::PostWait+90
   EventInternal::Wait+1f9
   LatchBase::Suspend+633
   LatchBase::AcquireInternal+415
   BUF::AcquireLatch+78
   BPool::Get+ea
   GlobalFileHeader::SetFileProperties+1e3
   FileMgr::InternalGrowFile+c3f
   FGCB::GrowAFile+8a6
   MakeSpaceInFileGroup+4a
   AllocationReq::AllocatePages+2514
   AllocationReq::Allocate+f3
   ExtentAllocator::PreAllocateExtents+1c8
   ExtentAllocatorSingleAlloc::PreAllocate+72
   ExtentAllocatorSingleAlloc::AllocateExtents+25c
   CBulkAllocator::AllocateExtent+24d
   CBulkAllocator::AllocatePageId+bc
   CBulkAllocator::AllocateLinkedAndFormattedLeafPage+c2
   CHeapBuild::AllocateNextHeapPage+1f
   CHeapBuild::InsertRow+14f
   RowsetBulk::InsertRow+2d4e
   CValRow::SetDataX+5b