Author: Peter Whyte
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LATCH_NL Wait Type in SQL Server
⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: PAGELATCH_EX Wait TypeRelated pillar: Performance & Troubleshooting LATCH_NL is the wait type for a Null (NL) mode latch on a non-page internal structure. NL is the no-op of latch modes, and this wait exists purely so the full set of modes…
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DBA Scripts: Get Index Fragmentation
🔧Part of the DBA-Tools Project, copy/paste SQL Server scripts and health checks.In: Maintenance & Automation › Index Maintenance Index fragmentation is one of those topics where the received wisdom, “rebuild your indexes every weekend”, causes almost as many problems as it solves. Rebuilding an index that doesn’t need it wastes a maintenance window, takes a…
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LATCH_SH Wait Type in SQL Server
⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: PAGELATCH_EX, TempDB Allocation ContentionRelated pillar: Performance & Troubleshooting LATCH_SH is the shared (read) counterpart to LATCH_EX. It is a wait for a shared latch on an internal SQL Server structure that is not a data or index page. Threads take a…
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LATCH_UP Wait Type in SQL Server
⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: PAGELATCH_EX Wait TypeRelated pillar: Performance & Troubleshooting LATCH_UP is a wait for an update-mode (UP) latch on an internal SQL Server structure that is not a data or index page. Update mode sits between shared and exclusive: the holder intends to…
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LOGBUFFER Wait Type in SQL Server
⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: WRITELOGRelated pillar: Storage & Capacity LOGBUFFER occurs when a session generating log records has to wait for free space in a log buffer. SQL Server stages log records in small in-memory log buffers (up to 60KB each) before flushing them to…
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LOGMGR_FLUSH Wait Type in SQL Server
⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: WRITELOG Wait TypeRelated pillar: Backup & Recovery LOGMGR_FLUSH is a wait recorded when a thread generating a transaction log record has to pause until the current log flush completes. From SQL Server 2016 onward the engine runs multiple background log writer…
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Unable to Open the Physical File (Error 5120)
SQL Server error 5120 reports an operating system error, and error 5 has two completely different causes: the file is already open, or the service account cannot read it. The message cannot tell them apart.
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PAGEIOLATCH_UP Wait Type in SQL Server
⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: PAGEIOLATCH_SH Wait TypeRelated pillar: Storage & Capacity PAGEIOLATCH_UP is a wait for an update-mode latch on a page that is currently in an I/O request, usually a thread reading a non-table page (typically an allocation bitmap like PFS, GAM, or SGAM)…
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DBA Scripts: Get Autogrowth History
🔧Part of the DBA-Tools Project, copy/paste SQL Server scripts and health checks.In: Storage & Capacity SQL Server autogrowth is one of those settings that is often ignored until it becomes a production problem. A database file growing during normal business hours is usually a sign that SQL Server is reacting to a capacity issue. The…
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PAGELATCH_DT Wait Type in SQL Server
⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: PAGELATCH_EX Wait TypeRelated pillar: Performance & Troubleshooting PAGELATCH_DT is a wait for a Destroy (DT) mode latch on a data file page that is in memory and not part of an I/O request. Destroy mode is taken when a buffer is…
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- DBA Scripts (152)
- High Availability (HA) (13)
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- Maintenance (25)
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- Security (Encryption & Permissions) (20)
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- T-SQL Fundamentals (15)
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- Wait Types (235)