--- title: Database Animations: Why Higher Maxdop Equals More... description: Setting Max Degree of Parallelism (MAXDOP) too high can increase the likelihood of TempDB spills. When a query runs single-threaded, its full memory grant goes... canonical: https://daily.dev/posts/database-animations-why-higher-maxdop-equals-more-tempdb-spills-s4rhrchn3 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Database Animations: Why Higher Maxdop Equals More TempDB Spills | daily.dev og:description: Setting Max Degree of Parallelism (MAXDOP) too high can increase the likelihood of TempDB spills. When a query runs single-threaded, its full memory grant goes... og:url: https://daily.dev/posts/database-animations-why-higher-maxdop-equals-more-tempdb-spills-s4rhrchn3 og:image: https://api.daily.dev/og/posts/s4RHrCHn3.png og:image:alt: Database Animations: Why Higher Maxdop Equals More TempDB Spills og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Database Animations: Why Higher Maxdop Equals More TempDB Spills **[Brent Ozar](https://daily.dev/sources/brentozar)** · 3 min read · 4 upvotes · 0 comments ## Summary Setting Max Degree of Parallelism (MAXDOP) too high can increase the likelihood of TempDB spills. When a query runs single-threaded, its full memory grant goes to one core, but when it goes parallel, that same grant is divided evenly across all cores involved. This means a higher MAXDOP raises the chance that one or a few threads experience parallelism skew and run out of memory, spilling to disk in TempDB - a problem made worse for queries affected by parameter sniffing. DBAs are advised to tune both Cost Threshold for Parallelism and MAXDOP together, while developers are pointed to sp_BlitzCache with @SortOrder = 'spills' to find and fix queries that are spilling. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why does increasing MAXDOP in SQL Server cause more TempDB spills? Because SQL Server divides a query's memory grant evenly across all parallel threads once it goes parallel, so a higher MAXDOP spreads that memory across more cores. If one thread experiences parallelism skew and needs more memory than its share, it spills the excess data to disk in TempDB, which happens more often as MAXDOP increases. _Track down MAXDOP and tempdb spill discussions like this one on daily.dev when tuning SQL Server performance._ ### How can I find SQL Server queries that are spilling to TempDB? Use sp_BlitzCache with the parameter @SortOrder = 'spills' to sort cached query plans by spill activity and identify which queries are dumping data to TempDB. Once identified, tune the indexes or the query itself to reduce the amount of work required, lowering the memory needed per core. _Developers debugging tempdb spills can follow SQL Server tuning discussions like this on daily.dev._ ## Similar posts on daily.dev - [Database Animations: You’ve Heard of Page Splits. 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If one thread experiences parallelism skew and needs more memory than its share, it spills the excess data to disk in TempDB, which happens more often as MAXDOP increases. Track down MAXDOP and tempdb spill discussions like this one on daily.dev when tuning SQL Server performance."}},{"@type":"Question","name":"How can I find SQL Server queries that are spilling to TempDB?","acceptedAnswer":{"@type":"Answer","text":"Use sp_BlitzCache with the parameter @SortOrder = 'spills' to sort cached query plans by spill activity and identify which queries are dumping data to TempDB. Once identified, tune the indexes or the query itself to reduce the amount of work required, lowering the memory needed per core. Developers debugging tempdb spills can follow SQL Server tuning discussions like this on daily.dev."}}]} ```