Wait time cxpacket. wait_type wait_time_s pct running_pct CXPACKET 22223396.
Wait time cxpacket. Use SQL Diagnostic Manager to visualize real-time wait stats. Aug 26, 2015 · Paul Randal (@PaulRandal) explains how to tell when CXPACKET waits are actually a problem (because, usually, they are just an indication of parallelism). Every time a SQL Server query has to pause (waiting for a resource or some condition), SQL Server records a wait type. MAXDOP value is 0 and the server has 36 cores, any thoughts? Feb 24, 2010 · In this tip we look at how to use DMV sys. This wait was added (SQL Server 2016 SP2, SQL Server 2017 CU3) in order to try and make CXPACKET waits more actionable - these should be “benign Dec 31, 2024 · SQL Server is a powerful database management system, but like any complex system, it often experiences resource contention and waits. Using Wait Stats to Find Why SQL Server is Slow Forget page life expectancy, buffer cache hit ratio, and disk queue length – those antiquated stats worked great for Grandpa, but it’s time to find an easier way to tune. wait_type wait_time_s pct running_pct CXPACKET 22223396. How can you tell which queries are causing those waits? Learn the pros and cons of different techniques to track down the cause of both common and tricky waits in SQL Server, including CXPACKET, PAGEIOLATCH, LCK, RESOURCE_SEMAPHORE, and THREADPOOL waits. Apr 14, 2022 · Boost query performance with CXPACKET insights. But in real-world queries there can be numerous different waits, all happening on different tasks that are busy doing various things on behalf of the query. Nov 14, 2012 · CXPACKET waits may or may not be an issue for a system, but on an OLTP style system, they can indicate costly queries that are executing and requiring parallelized plans. We explain the difference between the two, and talk about why troubleshooting this wait is so much harder in prior versions of SQL… To access this incredible, amazing content, you gotta get Mastering Server CXPACKET is probably the most confusing wait type, but things were supposed to get a little easier to interpret in SQL Server 2017 CU3 with the introduction of the CXCONSUMER wait type. You may consider lowering the degree of parallelism if contention on this wait type becomes a problem. dm_os_wait_stats, or check your waits with sp_Blitz® or sp_BlitzFirst®, one of your biggest wait types is probably CXPACKET. Oct 5, 2018 · Here's an example chart for CXPACKET, the most common wait type out there: I started going a little further than this, mapping out some of the more common wait types, and noting some of the properties they shared. In this blog, we will dive into the most common wait types, their significance, and how to troubleshoot them. We’ve got runaway iops maxed out (that’s a whole different story still ongoing) Interestingly, we saw an uptick in cxconsumer (previously only cxpacket) correlated with disk latency/throughout. Learn how to fix them. Yet the wait time is showing as 450000 ms on CXPACKET. This goal of this tip is to increase query performance, decrease high CXPACKET waits without reducing MAXDOP. Jan 13, 2016 · We have also noticed very high wait times: The combination of CXPACKET & LATCH_EX accounts for about 97% of all waits. By itself, the CXPACKET wait type is not an indication of any specific resource bottleneck, it is simply a synchronization wait. I observed CXConsumer wait types mostly and sometimes CXPacket. Brent Ozar talks about that here: Feb 13, 2009 · CXPACKET is the most consumable wait type. Feb 13, 2009 · The Thread 0 records the time between the start of the threads till the last thread is finished, in this case your CXPACKET wait time will be the time Thread 2 ran. Wait types provide insight into where SQL Server spends its time waiting, which often points to the underlying causes of performance bottlenecks. In this case we have a single task that is waiting on LCK_M_S and eight tasks waiting on CXPACKET. e. As I said the reasons here mentioned are not the major cause of the CXPACKET wait but any kind of scenario can create the probable wait time. This, along with CXSYNC_CONSUMER, were split out from CXPACKET in a bid to make investigating parallel plan performance issues easier. This means that the query is being executed by multiple threads at the same time, with each thread working on a different part of the query. 33 BROKER_RECEIVE_WAITFOR … Jun 2, 2021 · Experts , This is the wait type we are getting on a SQL 2017 server. Jul 18, 2022 · According to Pedro, this wait is the “safe” type of parallelism wait, as opposed to the CXPACKET wait type, which means work isn’t evenly balanced across all of our cores. dm_exec_session_wait_stats provides similar information by session. CXPACKET generall Mar 29, 2017 · The waittype it is linked to is CXPACKET. This makes it challenging to troubleshoot performance issues related to parallelism, as all queries report CXPACKET waits. History Back in September 2016 I created a Connect item (3102145) to split the CXPACKET wait into benign and actionable […] Sep 24, 2023 · This query sometime takes 6 minutes and some time takes less 2 minutes. What does this indicate? Does it mean that it has been 450000ms so far that the result of parallel processing is being combined? Jan 13, 2016 · CXPACKET is the wait time for everyone to finish and complete all their small tasks for the given project. Mar 24, 2014 · Learn about CXPACKET waits in SQL Server and how they work. Understanding how to identify and address these waits is crucial for optimizing your SQL Server applications. Dec 18, 2017 · Learn about the good, the bad and the ugly for CXPACKET and CXCONSUMER wait types in SQL Server. Aug 18, 2020 · Phil Factor sets out with the modest aim of giving you enough of an introduction to waits to better understand the wait information you get from a SQL Server monitoring tool like SQL Monitor, and the rather overwhelming amount of information available in the underlying DMVs and Extended Events. Feb 12, 2024 · That you have a process with last wait that is SOS_SCHEDULER_YIELD is perfectly normal. Wait statistics, in the context of SQL Server, refer to the amount of time that a query spends waiting to access data in the database. Get the scoop in this 35 minute video. May 14, 2025 · Unlock SQL Server performance by understanding wait types like CXPACKET or PAGELATCH. Aug 27, 2013 · When you query sys. Oct 31, 2019 · Thread0 registers for the CXPACKET wait type. Basically, CXPACKET is divided into 3: CXPACKET, CXSYNC_PORT, CXSYNC_CONSUMER. May 14, 2022 · SPOOL-TA-TOES When you spend a long time building indexes single threaded, you spend a long time waiting on CXCONSUMER (and not so much time at all waiting on CXPACKET). How to Fix or Address It Address storage issues (e. Explore configuration options to optimize CXPACKET waits. Oct 13, 2024 · In SQL Server, high CXPACKET wait time may come from skewed parallelism that is due to skewed data distribution. CPU-Related Wait Types SOS_SCHEDULER_YIELD : Occurs when a task voluntarily yields the processor to let another task run. Do you have an actual problem involving CXPACKET waits and nothing else? If so, what makes you think indexing is the solution? Nov 2, 2022 · Learn how to understand and optimize SQL Server CXPACKET wait types for query performance. CXPACKET Explanation: When a Dec 22, 2023 · Hello, we have stored proc that has two UPDATE statements within and can range from 5 mins to maybe about 1 hour to complete. High CXPACKET wait times often indicate that parallelized queries are not optimally balanced, with some threads completing faster than others, leading to inefficiencies. Let’s talk about what’s really going on. It occurs when trying to synchronize the query processor exchange iterator. CXPACKET : Indicates parallel query Oct 29, 2014 · CXPACKET accumulates waits for every logical processor SQL Server uses in any parallel queries. We have also noticed very high wait times: The combination of CXPACKET & LATCH_EX accounts for about 97% of all waits. Mar 26, 2015 · What you're seeing is the threads with CXPACKET waits are actually done with whatever work they had to do and are now waiting for the other active threads (the ones with NULL as the wait type) to complete. Learn wait types like CXPACKET & LCK_M_XX to boost performance. Recently this was hanging (SUSPENDED state and had CXCONSUMER wait type) throughout the entire day yesterday near 24 hours and… Jan 13, 2016 · The SQL-Server instance in question has very high CPU usage (higher than 90% on all 16 cores all the time) during business hours. This article explains SQL Server wait type CXPACKET. Feb 6, 2011 · CXPACKET has to be most popular one of all wait stats. Nov 11, 2024 · Explore CXPACKET and CXCONSUMER wait types in SQL Server. CXPACKET is probably the most confusing wait type, but things were supposed to get a little easier to interpret in SQL Server 2017 CU3 with the introduction of the CXCONSUMER wait type. I have commonly seen this wait stat as one of the top 5 wait stats in most of the systems with more than one CPU. Brent O had a great analogy using a classroom. By analysing these wait stats, DBAs, developers, and system administrators can pinpoint bottlenecks more easily than by poring over old-school metrics like The CXCONSUMER wait type, like CXPACKET, is related to parallelism but has a different role. If SQL Server doesn’t balance that work evenly across multiple threads, you can experience the CXCONSUMER and/or CXPACKET wait types. CXPACKET stands for Class eXchange Packet. Sep 26, 2025 · How to Spot It Run sys. As a result, a queries’ elapsed time is a factor of the longest running parallel task. Books On-Line: Occurs when trying to synchronize the query processor exchange iterator. The system consists of 3 processing SQL Servers which do alot of number crunching and calculations and then feed the data into a central cluster server. Then we talk about how to fix it long term, and why you can’t make it go away with settings alone. Each wait type is broken out and accompanied by information on how many waits there are, and how long the waits have been outstanding. You should check the session that's responsible for the CXPACKET and see what exactly it's waiting for: SELECT session_id, wait_type, wait_time, start_time, * FROM SYS. They measure time in seconds or milliseconds – depending on the stat you’re viewing. The SQL Server CXPACKET wait type is one of the most misinterpreted wait stats and here we are going to discuss troubleshooting with this wait type. Jan 22, 2023 · In several service requests our customers asked how to check the performance of a database. This wait type occurs when the query or workload is running in parallel, with more than one thread being used by SQL Server database engine to execute the query. Jan 28, 2024 · Unlock SQL Server efficiency. Best Practices to Reduce CXPACKET wait: Refer earlier article regarding MAXDOP and Cost Threshold. Jan 6, 2014 · Is there a way to find query plans that are accruing CXPACKET waits? Those waits are not currently in progress, I saw them in aggregated waits statistics (dm_os_wait_stats). Feb 7, 2011 · This may lead to CXPACKET wait. Traditionally, SQL Server reports both “good” and “bad” parallelism using the CXPACKET wait type. See how SQL Server parallelism settings impact CXPACKET and CXCONSUMER wait type results. Oct 7, 2023 · Decoding CXCONSUMER Wait Types in SQL Server: Causes, Solutions, tips to avoid and Performance Optimization. You may consider lowering the degree of parallelism if contention on this 1. Oct 18, 2014 · The waiting tasks then post out their wait time as CXPACKET while the other tasks continue to run or wait on other wait types and resources. 33 BROKER_RECEIVE_WAITFOR … Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) Returns information about all the waits encountered by threads that executed. You can use this aggregated view to diagnose performance issues with SQL Server and also with specific queries and batches. I am seeing a high amounts of CXPACKET wait t Dec 7, 2020 · CXPACKET and CXCONSUMER wait types in SQL Server are common occurrences when managing database performance. , slow disks = high PAGEIOLATCH). High values may indicate CPU pressure or inefficient query plans. This is split about 50/50 between CXPACKET & LATCH_EX. Until all parallel tasks are completed, the query will not complete. Dec 20, 2024 · SQL Server wait types provide insights into how SQL Server is spending time waiting for resources, which can help identify performance bottlenecks. Is the CXPACKET wait specifically contributing to a performance problem? How do you know this? Are there other telling waits (like latch waits) coming in Apr 30, 2025 · CXPACKET : Represents waits related to parallel query execution in SQL Server. However, since SQL Server 2016 SP2 and SQL Server 2017 CU3, its significance has changed due to the introduction of Yesterday’s post was all about blocking, and the fact that a given request can have multiple waits reported by the DMVs. During this discussion we reached to discuss why is important to check Wait Stats, for example, CXPACKET, SOS_SCHEDULING_YIELD, PAGEIOLATCH, PAGELATCH, etc. Apr 18, 2017 · CXPACKET waits are usually associated with parallelism and particularly the case where multi-threaded queries have been stuck waiting for one or more of the threads to complete – i. Aug 12, 2020 · @Veelen van, Klaas /All As part of a fix CXPACKET waits were further broken down into CXSYNC_CONSUMER and CXSYNC_PORT (and data transfer waits still reported as CXPACKET) as to distinguish between different wait times for correct diagnose of the problem. You may consider lowering the degree of parallelism if a conflict concerning this wait type develops into a problem. This is parallelism and CXPACKET wait type in action. Being able to put the waits together with the query plan can help you tune queries more efficiently. This can stem from skewed data distribution, outdated statistics, or excessive parallelism. CXPACKET waits occur when a parallel query is executed and one or more threads have to wait on one of the other threads to complete. What concerns me and what I really would like to know is why the number 1 of the SPID 78 is suspended. the threads are taking different lengths of time because the load hasn’t been split evenly. It would also suffer from multiple personalities, because what it represents, parallelism, is complex with many moving parts. Introduced in SQL Server 2016, CXCONSUMER tracks the time spent by threads waiting for other threads in parallel query execution. We explain the difference between the two, and talk about why troubleshooting this wait is so much harder in prior versions of SQL… To access this incredible, amazing content, you gotta get Mastering Server I have gathered wait stats from a one hour peroid which show a large amount of CXPACKET and LATCH_EX wait events. dm_exec_requests Jun 23, 2015 · The only time non-control threads will register CXPACKET waits is if they complete before the other threads in the operator. If necessary, you can play with the max degree of parallelism setting. Ok, so all good, but when does the CXPACKET wait type trigger? Well, in parallelism, the distribution of work is uneven among the threads. We'll look at a real-world example to We now see the full picture, including both the lock wait and all of the CXPACKET waits. In a performance scenario, normally, I used to review two Dec 13, 2024 · Understanding the Top 10 Most Common Wait Types in SQL Server When managing SQL Server Performance, understanding wait types is crucial for diagnosing and troubleshooting issues. Discover SQL Server wait types like LCK_M_X and CXPACKET that cause blocking. It is also one of the most misunderstood wait types and sometimes has little impact on your query performance. Dive in for quick fixes and expert insights. Reduce your wait times. Jun 28, 2018 · We are experiencing some slowness on our MS SQL Server 2016 database, I have been using Brent Ozar's first aid kit to do some initial troubleshooting. Please see the CXPACKET wait for more information on how to understand and troubleshoot those waits. In fact, lowering CXPACKET wait times may degrade the performance of your query! May 6, 2019 · What does CXCONSUMER really mean? For reference, here’s the description from the Microsoft Docs: Occurs with parallel query plans when a consumer thread waits for a producer thread to send rows. Jan 6, 2017 · The CXPacket wait is not a problem. This page explains the CXPACKET wait type and gives examples of where it occurs in SQL Server. Excessive CXPACKET wait types present alongside with excessive PAGEIOLACH_SG wait types is often an indicator that index scan is the actual cause of excessive PAGEIOLATCH_SH This wait type was added in Azure SQL Database and Azure SQL Managed Instance and is now in SQL Server 2022. g. A CXPACKET wait is typically reported during parallel query operations. De-fragmentation of Index can help as more data can be obtained per page. SQL Server parallelizes a query by dividing each query operation into equal sized sets and by splitting up these sets into multiple threads targeting specific processors for parallel processing. Because not all the threads complete at exactly the same time, the Jun 25, 2024 · Identify and address high wait statistics of parallelism type in SQL Server to optimize performance and troubleshoot issues effectively. The CXPACKET wait type most probably is not what is causing your problem, but rather a consequence of it. which I can understand because there are 9 78s as you can see on the picture below. The teacher hands out a bunch of different stacks of paper to the class and has them find a word on them. Demo Code If you want to follow along with… To access this incredible, amazing content, you gotta get Fundamentals of Server Sep 23, 2020 · If wait stats were celebrities, then CXPACKET would be a superstar, showing up in a gauche limo and getting swarmed by nerdy fans asking for an autograph. Also, high CXPACKET waits aren't necessarily a problem (something will always be your highest wait). To show how SQL Server ends up waiting, let’s write I’d treat that the same way as for CXPACKET and look for skewed work distribution, or unwanted parallelism, or something else causing the parallel threads to wait. Understand how parallelism works in SQL Server and the scenarios where excessive CXPACKET waits can occur. So cxconsumer is a sign of threads waiting, but likely on other subsystems than just cpu. sys. Specifically, it showed the time a worker thread waited during coordination with other threads involved in a parallel query. The official definition suggests that CXPACKET Wait Stats occurs when trying to synchronize the query processor exchange iterator. 71 14. 33 14. Learn their roles in parallel query execution and how to manage them effectively. Understanding wait types in SQL Server is crucial for diagnosing and resolving performance bottlenecks. And just wait longer for things to complete. When this wait is reported, it typically means there are additional tasks performing work in parallel. This can happen if one of the threads gets stuck waiting for a resource for a long time, so look to see what the wait type is of the thread not showing CXPACKET (using my script above) and troubleshoot appropriately. Q: Can CXPACKET delays be totally eliminated? Nov 25, 2015 · CXPACKET is one of the famous wait type that database administrators are experiencing, in this article you will find out how to avoid them. Optimize parallelism settings if CXPACKET is . We will look at a few examples of a query and the impact on CXPACKET waits. Aug 14, 2025 · Key Things to Know About Wait Stats They’re cumulative – Wait times are aggregated since the last time the data was cleared, usually at the last server restart (though other events can reset them). Whenever SQL Server is running queries, it’s tracking how much time it spends waiting on Jul 26, 2016 · So, one thing to try when troubleshooting queries that get stuck for extended periods of time in a CXPACKET wait state is to insure that statistics on the tables are updated. May 25, 2017 · GraphCommentYou’ve got some troubling wait stats in SQL Server. Jun 3, 2018 · The wait_type of CXPACKET gives us a clue as to why. So is that a huge issue? Jan 24, 2019 · Regarding the differences, I'm wondering should I have to ignore CXPACKET and Redo_Thred_Pending_Work wait and work on the root cause of PageIOLatch_SH wait (maybe poor indexing). The SQL Server CXPACKET wait type is a result of parallel query execution and indicates that a session is waiting for the synchronization of threads involved in the parallel process to complete. Q: Is there a particular CXPACKET wait time threshold at which I should be concerned? Ans: Your individual workload and performance goals will determine your own wait time threshold. Nov 1, 2013 · Unless CXPACKET constitutes a very high percentage of total wait time, it usually does not mean it is a performance problem. Translated into questions a tuner might have about a wait type they are experiencing: Can the wait type be solved at the query level? Jan 7, 2012 · In this post I will go through the SQL Server Wait Type CXPACKET, what is this wait type a symptom of, and how you could go about diagnosing and optimizing the CXPACKET wait type. They track the time SQL Server tasks spend waiting for resources, providing insights into areas However, when parallelism is not working well, it can lead to skewed workload distribution and increased wait times. SQL Server performance tuning can feel daunting, but one of the most effective approaches is to focus on wait statistics. CXPACKET The CXPACKET wait type traditionally indicated waits related to parallel query execution. (from BOL) Jun 5, 2018 · I’m a little bit overdue to blog about this new wait type, but I wanted to wait until SQL Server 2016 SP2 was released for a bit and people started seeing this new wait type. among others, because that means what is waiting for SQL Server to execute the workload. Discover Stedman Solutions for expert tuning. Don’t have time to watch? Scroll Jan 26, 2025 · Wait statistics in SQL Server are crucial for understanding performance and identifying bottlenecks. The CXPacket wait itself is not of interest or really concern. In the example I used for the post, most of these waits were CXPACKET. Explore more now! Jan 12, 2023 · CXPACKET By far the most common CPU-related wait type in SQL Server instances deployed uses default, out-of-the-box, configuration options. dm_os_wait_stats to help troubleshoot and understand what resources may be slowing down SQL Server. The processing servers can have up to 6 jobs running each at any one time. Oct 11, 2024 · Discover key SQL Server wait types that contribute to blocking and learn strategies to manage them effectively for better performance. Mar 15, 2018 · In this tip we examine how changing a query can impact CXPACKET waits. Jul 7, 2014 · The problem is not cxpacket wait invents by themselves, analysing a single query I can find that the CXPACKET wait is, in the most cases, higher than the elapsed time. This wait type means that the worker is waiting for some other operation to complete before it can go on. This is a normal part of parallel query execution. May 13, 2022 · Why does MAXDOP = 0 result in high CXPACKET wait time? Ask Question Asked 3 years, 5 months ago Modified 3 years, 5 months ago I show you a query that produces CXPACKET waits, measure it with sp_BlitzFirst (formerly sp_AskBrent), and explain what the cryptic letters in CXPACKET stand for. Explore different query versions and strategies to minimize CXPACKET waits. It will always post a CXPacket wait May 31, 2016 · Learn about the SQL Server CXPACKET wait type and its implications for query execution. This guide will walk you through extracting SQL Server CXPACKET Wait Time data, enabling you to pinpoint and resolve performance issues effectively. Understanding the performance issues in CXPACKET and CXCONSUMER wait types in SQL Server, and how to see what's causing them. I am seeing a session that is having suspended status, which means it is waiting for something like IO. Check out the real world CXPACKET and CXCONSUMER wait types example May 31, 2017 · Usually you worry about CXPACKET waits once you've solved any other problems, and by that time indexing is probably not what will resolve such waits. Learn strategies to reduce wait times and boost your system's performance. Worth noting, I’m dealing with something kinda similar. . Wait Type CXPACKET The wait type CXPACKET is ranked #11 by Stedman Solutions and Database Health Monitor. Aug 9, 2022 · I am monitoring the requests and sessions using dmv's. dm_exec_requests only shows thread 0 of a parallel query and, as I explained above, thread 0 is the controller thread. Aug 2, 2011 · CXPacket is a parallel skew, it means that some threads of the parallel query are waiting for other threads. What Are Wait Types in SQL Server? Wait types Nov 13, 2010 · Before we continue the resolution, let us understand what CXPACKET Wait Stats are. Understand how to optimize parallelism usage with the MDOP and 'Cost threshold for parallelism' settings. Using live execution plans, wait monitoring, and worker SQL Server CXPACKET Wait Time is a common performance bottleneck. Learn why reducing cores isn't always best and how to tackle excessive waits effectively. Aug 1, 2025 · This article dives deep into cxpacket and cxconsumer in sql server, explaining how to simulate each, when they appear, and why they matter. What we need to take into Feb 10, 2017 · A lot of times, all it really does it reduce you throughput so that you don't see the CXPacket waits. When a process goes parallel, you end up with something called "execution contexts"—the simplest way to think of these are as the individual chores being divided up to the various threads to run. dm_os_wait_stats to view server-wide wait types. This article will explain common wait stats which can help to improve SQL Server performance. Look for high counts/durations in waits like PAGEIOLATCH, CXPACKET, or LCK_M_X. That follows from the concept of co-operative multitasking, as I explained above. Sep 1, 2020 · Hi everyone! Are there any recommendations or good configuration practices for the treatment of the CXPACKET bottleneck? All help is welcome! Jun 2, 2021 · Experts , This is the wait type we are getting on a SQL 2017 server. Unlike CXPACKET, CXCONSUMER is not typically associated with performance issues but is more of an internal tracking mechanism. So, you can't think about it as clock time. Sep 10, 2023 · Ans: Wait delays happen when parallel queries don’t synchronize well; they are intimately tied to parallelism. Jul 24, 2018 · Let’s say you’ve got a query, and the point of that query is to take your largest customer/user/whatever and compare their activity to smaller whatevers. Jul 16, 2024 · The CXPACKET wait type is a common wait type that occurs in SQL Server when a query is executing in parallel. irnesna pnzrd f5s hggx oy5jalpb svfgz zufd 6bhoqm jm21u lhzb