SQL Server Lock Wait Types
There are many different types of lock within SQL Server. The table below gives a short description of each:
| Wait Type | Description |
|---|---|
| LCK_M_SCH_S | Schema stability |
| LCK_M_SCH_M | Schema modification |
| LCK_M_S | Share |
| LCK_M_U | Update |
| LCK_M_X | Exclusive |
| LCK_M_IS | Intent-Share |
| LCK_M_IU | Intent-Update |
| LCK_M_IX | Intent-Exclusive |
| LCK_M_SIU | Shared intent to update |
| LCK_M_SIX | Share-Intent-Exclusive |
| LCK_M_UIX | Update-Intent-Exclusive |
| LCK_M_BU | Bulk Update |
| LCK_M_RS_S | Range-share-share |
| LCK_M_RS_U | Range-share-Update |
| LCK_M_RI_NL | Range-Insert-NULL |
| LCK_M_RI_S | Range-Insert-Shared |
| LCK_M_RI_U | Range-Insert-Update |
| LCK_M_RI_X | Range-Insert-Exclusive |
| LCK_M_RX_S | Range-exclusive-Shared |
| LCK_M_RX_U | Range-exclusive-update |
| LCK_M_RX_X | Range-exclusive-exclusive |
DBTuna will monitor time spent in any type of lock, so if you see excessive wait times on any of these lock types for a particular stored procedure or statement, then you need to investigate the blocking session.
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