table_options signifies table options of the kind that can be used in the CREATE TABLE statement, such as ENGINE, AUTO_INCREMENT, AVG_ROW_LENGTH, MAX_ROWS, ROW_FORMAT, or TABLESPACE. See Online Index Operations. If the response is helpful, please click "Accept Answer" and upvote it. sakuraime 2,311. First, we will start the index reorganization in a session using the following T-SQL code. ". This tip will explore two features to speed up SQL Server index and statistics maintenance. Syntax: ALTER INDEX [schema. The MSDN ALTER INDEX page says "An index cannot be reorganized when ALLOW_PAGE_LOCKS is set to OFF. Compacting this data can improve disk space use. Click the "Tablespaces" link. . WITH FULLSCAN. Both are deprecated in favour of ALTER INDEX where. Sometimes I noticed that my database experiences high locking and. The fix: Figured out that this cannot be done. The indexoptimize_user_databases job. _depth, index_level). 1 avg_fragmentation_in_percent. So your db need to have: data space to accomodate your new index, data space to make a sort since you used SORT_IN_TEMPDB = OFF, and it needs log to be large. I don't agree with Kin this is a knee response that will be a least help. Regards Echo ALTER INDEX is in fact just an alias for the forms of ALTER TABLE that apply to indexes. Example: 3. It can only be fixed by doing an ALTER INDEX. ALTER INDEX. The equivalent statistics update can be achieved by: UPDATE STATISTICS . The equivalent statistics update can be achieved by: UPDATE STATISTICS . The following advantages will be provide using alter index <name> rebuild online: o DMLs are allowed on the base table1 Answer. This means long-term blocking table locks are not held and queries or updates to the underlying table can continue during the ALTER INDEX REORGANIZE transaction. Name + ' ON ' + T. 1. IndexOptimize is supported on SQL Server 2008, SQL Server 2008 R2, SQL Server 2012, SQL Server 2014, SQL Server 2016, SQL Server 2017, SQL Server 2019, SQL Server 2022, Azure SQL Database, and Azure SQL. Follow edited Jul 26, 2022 at 15:50. Ovaj preglednik više nije podržan. ドメイン索引を変更する場合は、索引の索引タイプに対してexecute. DECLARE. This caused the system to reorganize or rebuild some indexes even. ALTER INDEX REBUILD is an offline operation on Standard Edition in the sense that it requires locks. alter index all on table_name reorganize; But I only want to rebuild or reorganize if fragmentation percentage on each index is between a certain range. Please sign in to rate this answer. So an index reorganize is extremely space efficient, and is one of the reasons I wrote the original DBCC INDEXDEFRAG for SQL Server 2000 (the predecessor of ALTER INDEX. If you are satisfied with the unused space of table, then check the unused space of the database using the same command without specifying a table. It. Here is the syntax for the same. You need the name to be able to drop the index. These values provide a rough guideline for determining the point at which you should switch between ALTER INDEX REORGANIZE and ALTER INDEX REBUILD. Avoid using this feature in new development work" and "Use ALTER INDEX…REORGANIZE to reorder the leaf-level pages of the index in a logical order", and then it proceeds to use the old code in. The maximum length of the parameter string is 1000 characters. It's better to do reorg on Nightly. When you don't explicitly name the constraint / index, a name is auto-generated. [FactInternetSales] REBUILD PARTITION = ALL WITH. The documentation for alter index, for example, shows that it accepts an index_name, not an expression that might evaluate to an index name. -- Test 2: ALTER INDEX REBUILD-- Rebuliding should work fine ALTER INDEX [PK_TableName] ON [dbo]. To create SQL database maintenance plan, launch SQL Server Management Studio > expand the database instance > Management > right-click on the maintenance plan > New Maintenance Plan. indexoptimize" within my script that iteratates through the for me relevant tables, job seems to be. IndexOptimize is the SQL Server Maintenance Solution’s stored procedure for rebuilding and reorganizing indexes and updating statistics. The name of an index-method-specific storage parameter. Syntax: ALTER INDEX [ IF EXISTS ] name RENAME TO new_name ALTER INDEX [ IF EXISTS ] name SET TABLESPACE tablespace_name ALTER INDEX [ IF EXISTS ] name SET ( storage_parameter = value [,. See this blog post for details. Document table. New ALTER INDEX UPDATE BLOCK REFERENCES syntax fixes the invalid physical guesses without reconstructing. The syntax for rebuilding indexes is very simple, we just add the "WITH ONLINE=ON" clause to the ALTER INDEX command. Alter Index in PostgreSQL 9. Right-click the index that you want to modify and then click Properties. You don’t need to run both against the same index. Expand the Indexes folder. Let us try to rebuild the columnstore index online in SQL Server 2017 and SQL Server 2019. x) and SQL Server 2014 (12. Poorly designed indexes and a lack of indexes are primary sources of database application bottlenecks. ALTER INDEX REBUILD command has a few forms:ALTER INDEX ALL ON mytablename REORGANIZE PARTITION= @switch_partition and then the thread being blocked (which doesn't show either in sql_text or sql_command) has wait type: (2652058ms)LCK_M_SCH_M. -- Create a database CREATE DATABASE [ columnstore ]; GO -- Create a rowstore staging table CREATE TABLE [ staging ] ( AccountKey int NOT. The only way to remove index fragmentation without causing data file growth again is to use DBCC INDEXDEFRAG or ALTER INDEX. With very large indexes, rebuilds take longer, generate more log, impact performance more while they’re running. ALTER INDEX TableDetails_UK0 ON TableDetails REBUILD WITH ( PAD_INDEX=OFF, SORT_IN_TEMPDB=ON. In SQL Server 2014, new functionality was introduced that allows you to control how the blocking mechanism, that is required by the online index rebuild operation, is handled. So your db need to have: data space to accomodate your new index, data space to make a sort since you used SORT_IN_TEMPDB = OFF, and it needs log to be large. 3 Answers. For an [!INCLUDEssazuresynapse-md] table with an ordered clustered columnstore index, ALTER INDEX REORGANIZE does not re-sort the data. SQL Server ALTER INDEX Syntax. Oracle Databaseのインデックスの再作成・変更SQL「alter index」とそのポイントを紹介します。 「alter index」は各種メディアやブログで紹介されており、指定できるパラメータも多くあります。 この記事では初心者向けにインデックスを再作成・変更する時の重要なポイントも合わせて紹介します。 In earlier versions of Microsoft SQL Server it could cause system slowdown to reorganize or rebuild a large index. If you need more tempdb space, scale up the pool. Recreate all indexes of the specified table. ALTER INDEX REORGANIZE is fully logged regardless of recovery mode. dm_db_column_store_row_group. The LOB data types are image, text, ntext, varchar(max), nvarchar(max), varbinary(max), and xml. Your replica/ mirrors may fall behind. Reorg the Indexes if the Fragmentation level is > 5% and <30%. References: QUESTION 39 You administer a Microsoft SQL Server database named Sales. ON [my]. You can reorganize an index-organized table or an index-organized table partition (to recover space or improve performance) without rebuilding its secondary indexes. This ALTER FULLTEXT INDEX statement starts a full population, which is the default behavior of the SET SEARCH PROPERTY LIST clause. Scale back down once the index rebuild is complete. You could also refer another query which may be helpful to you. tables T ON I. TEST_INDX DISABLE ; alter index IX1 on DBO. REORGANIZE WITH (LOB_COMPACTION = ON) to compact LOB pages of the underlying heap (this will leave the disabled indexes alone); Perform ALTER TABLE . ALTER INDEX All ON tableName REORGANIZE;ALTER INDEX PK_MyFragmentedIndex ON dbo. VeryImportantTable REBUILD; GO The second method is to reorganize indexes. REORGANIZE is your option. This process doesn’t drop indexes; It physically reorganizes the leaf nodes of the index. Disabling indexes. Question 1: Consider a scenario where you issue a full backup. gif」の説明 図「alter_index_partitioning. Change the index option settings. Modify an existing index on a table or view. You can also change this threshold via parameters. Reorganize the index. I used the sp_who2 procedure to see which queries were waiting, and which other query they were blocked by. REORGANIZE command (more details on this command and its usage are given below). ALTER INDEX statement can be used to change the properties of an index, such as its fill factor or sort order, or to rebuild or reorganize the index. ALTER INDEX . As the max possible rows in a row. column_store_dictionaries returns no rows at all. REORGANIZE) more than 30% logical fragmentation, rebuild it. RedDk 31-Aug-13 15:32pm. [FooDetail] REORGANIZE WITH (LOB_COMPACTION = ON) Extend event info: SQL Server 2017 provides a key feature Resumable Online Index Rebuilds. 2. Right-click the index that you want to modify and then click Properties. If a nonclustered index is being rebuilt, a shared lock is held on the table in question during the operation. tables And then copying and pasting the output to a new query window and running that. Finally, in case you’re wondering about parallelism and reorganizing indexes…the WITH (MAXDOP = n) option is not available for ALTER INDEX REORGANIZE, as index reorganization is always a single-threaded operation. alter the column as VARBINARY(MAX). However, the. I cannot say that index reorganize job was the reason for slowness because for me its a light activity. For example, you can add or remove a column from the index key, or change the setting of an index option. I am using the following to rebuild the index. So in order to fix my issue I went ahead and rebuild my index which fixed the issue. ALTER INDEX TableDetails_UK0 ON TableDetails REBUILD WITH ( PAD_INDEX=OFF, SORT_IN_TEMPDB=ON. We would like to show you a description here but the site won’t allow us. See if you can find the index name either in whatever UI you use for Synapse or by querying the sys. To learn more about index rebuild and reorganize operations, review this tip. Cancelling / Stopping ALTER INDEX REORGANIZE. Next, let us build only the clustered index and see the output of all the indexes. Rebuilding an index drops and re-creates the index. object_id = t. In this example, the code creates a daily SQL Agent job that runs at 23:30 (11:30 p. Here are a couple of examples. column_name DISABLE; ALTER INDEX index_name ON table_name. Reorganizing an index only deals with the fragmentation that exists, and the more fragmentation there is, the longer a reorganize will take. Partitions can be rebuilt individually. 20, “CREATE TABLE Statement”. Rebuild the index. I use SQL Server 2008 R2, I need to rebuild the index for every table in a database. SSC Guru. REORGANIZE index. Important. In PostgreSQL, ALTER INDEX command changes the definition of an existing index. upvoted 1 times Matt2000 3 months ago I agree. Then issue some transaction log backups, next a differential backup, followed by more transaction log backups, then another differential and finally some transaction log backups. Lock durations are short and will cause minimal blocking of queries. 1) The first step is to export the data from the index-organized table. Open the Tables folder & expand it. The first rebuilds a single index on a table and the second rebuilds all the indexes on the table. Designing the SQL Server Reorganize Index Task Perform ALTER INDEX ALL . DBREINDEX will always defragment as clean copies are made whereas INDEXDEFRAG churns pages. Monitor tempdb during rebuild operations. REORGANIZE, or to rebuild the index using ALTER INDEX. Expand the Indexes folder. [TBLTest] REBUILD WITH (MAXDOP = 2) This statement executes successfully without errors but again, when I check the properties of the index it's still at 0. 4 Answers. To create a table. Index automation job script. MySQL "plays it safe". The second part of this tip is intended to reduce the duration for update statistics as it pertains to both. ;WITH cte AS ( SELECT object_id, index_id, partition_number, rows, ROW_NUMBER () OVER (PARTITION BY object_id, index_id, partition_number. 図「key_compression. REORGANIZE. You can optionally specify * after the table name to explicitly indicate that descendant tables are included. After trying each the above options, I tried scripting the index as a Create statement and I don't see the MAXDOP option in the script. REBUILD) These numbers are made up. The second part is that you can not alter any indexes, this means, that you should DROP the old index and. First off: ‘Reorganize’ and ‘Rebuild’ are two different operations that each reduce fragmentation in an index. Increasing MAXDOP. Then try copying the data into a completely new table. Expand the Indexes node. (About 1 TB of data including myIndex (non-clustered)). You must rebuild each partition or subpartition. TEST REORGANIZE We get our open delta store again, which will cause locking. In previous versions of SQL Server, we might need to cancel the index maintenance operation either due to running out of time in the maintenance period, blocking issues or maybe low disk space due to the transaction log filling up. To reorganize index SQL Server, right-click it & choose Reorganize. PARTITION Only rebuild/reorganize one partition of the index. If you’re using high availability features like Availability Groups or database mirroring that stream the log between replicas, generating a lot of log data very quickly can create problems. The script which they were using to rebuild indexes, they had to add only keywords WITH (SORT_IN_TEMPDB = ON) at the end of the same. x), REORGANIZE hanya digunakan untuk memadatkan grup baris TERTUTUP ke dalam penyimpan kolom. Click the plus sign to expand the table on which you want to rebuild an index online. This clause specifies the parameter string that is passed uninterpreted to the appropriate ODCI indextype routine. There are scripts out there that will go though and reorganize verses rebuild versus skip. Changing the table's owner automatically changes the index as well. DECLARE @Database VARCHAR (255) DECLARE @Table VARCHAR (255) DECLARE @cmd NVARCHAR (500) DECLARE @fillfactor INT. Use The ALTER INDEX statement to rebuild an index part of a constraint definition; the constraint doesn't have to be dropped and added again with. INDEX. As you can see here, a Sch-M lock has a conflict with almost every locking. Statistics on indexes automatically get updated. 1. SELECT 'ALTER INDEX all ON ' + name + ' REORGANIZE;' + CHAR(10) + 'ALTER INDEX all ON ' + name + ' REBUILD;' FROM sys. Changing the table's owner automatically changes the index as well. ". Add a Solution. ¿ Rebuild indexes online. From the documentation: “When a clustered index is dropped OFFLINE, only the upper levels of clustered indexes are removed; therefore, the operation is quite fast. (About 1 TB of data including myIndex (non. partition_number The number of an existing index partition to rebuild/reorganize. This makes it more likely that some other session is blocked by your session, and that you may, in turn, become blocked by a lock held by that session. If index is range-partitioned or hash-partitioned, then Oracle Database deallocates unused space from each index partition. When investigating we found that the index reorganise for the clustered index of FooDetail takes between 90 minutes and 120 minutes. One of the blocking scenarios I find most interesting is related to online index rebuilds. 1. Syntax of ALTER INDEX. ROIR_Test4 REBUILD WITH ( RESUMABLE = ON, ONLINE = ON ); The result is quite sad: Msg 11433, Level 15, State 1, Line 17 'ALTER INDEX ALL' with RESUMABLE option is not. In the Index Properties dialog box, make the desired changes. ALTER INDEX. In columnstore world an update translates into a delete + insert and a delete is "deferred". If you’re using high availability features like Availability Groups or database mirroring that stream the log between replicas, generating a lot of log data very quickly can create problems. This browser is no longer supported. For an [!INCLUDEssazuresynapse-md] table with an ordered clustered columnstore index, ALTER INDEX REORGANIZE does not re-sort the data. SQL accepts the challenge of sorting the leaf-level pages in the. Qualification Limit for REORGANIZE to remove deleted rows from a rowgroup in Columnstore Index: By default when one runs ALTER INDEX REORGANIZE the qualifying limit to remove delete rows from a rowgroup is --> the specific rowgroup have 10% of the max possible rows in a rowgroup deleted. This prevents modifications to the table. Because the data_compression option is not retained when scripting out the Index create statement. 000). Follow edited Dec 16, 2020 at 8:43. If you read complete article it was trying to point out the commands or operations in SQL Server which would require additional disk space and others that would not. –Rebuild/Reorganize indexes on all the tables on a database based on the fragmentation. They work differently toward the same end. Check total_pages in sys. Particularly if you are in full recovery. No, there is no auto-magical defragging of indexes. Expand the database table on which you want to rebuild the index online. . indexes) [allow_page_locks] is SET to 0. Recreate the specified index. Here are a couple of examples. It creates a table that has multiple rowgroups, and then demonstrates how REORGANIZE merges the rowgroups. The name of the extension that the index is to depend on. TEST_INDX REBUILD WITH (DATA_COMPRESSION = PAGE); alter index IX1. Here is another syntax for reorganizing the index. For example, the following activities can modify the state of rowgroups: index build, index reorganize, bulk insert, tuple mover compressing delta stores. object_id WHERE I. The second part of this tip is intended to reduce the duration for update statistics as it pertains to both. This form of REINDEX cannot be executed inside a transaction block. Since it involves p_first and that partition is huge, it takes a long time, and locks the table. I'm modifying our index reorg/rebuild process to be sensitive to indexes that have ALLOW_PAGE_LOCKS turned OFF. You need to assemble the SQL prior to calling SP_ExecuteSQL, i. Assume the following conditions are true before creating the clustered index: The existing table (heap) contains 1 million rows. onemorecoke. In the Rebuild Indexes dialog box, verify that the correct index is in the Indexes to be rebuilt grid and click OK. Memory requirements for partitioned index operations that require sorting can be greater if the Query Optimizer applies degrees of parallelism to the build operation. Note: One thing ALTER INDEX does not allow you to do is change the set of columns that comprises the. And if it is a clustered index, the entire table is copied. 3) You cannot also specify the deallocate_unused_clause in this statement. One of the major reasons I wrote DBCC INDEXDEFRAG for SQL Server 2000 was as an online alternative to DBCC DBREINDEX. When the. An index cannot have an owner different from its table's owner. Reorganize indexes in a table using Transact-SQL. You don’t need to run both against the same index. delete of a row which was not yet copied). DISABLE to disable all non-clustered indexes; Perform ALTER INDEX ALL . REORGANIZE instead of REBUILD. Let’s use DBCC SHRINKDATABASE to reclaim the empty space. The final post in this series will cover parallelism and the UPDATE STATISTICS command, and if. extension_name. The stored procedure is using dynamic SQL to generate the alter index scripts. When I run a maintenance plan to reorganize and rebuild tables indexes, it fails. myTable REBUILDIt sets deadlock priority to 10 (the highest possible value), then performs inserts and deletes until >50% index fragmentation is achieved. Click OK. alter index ALL on dbo. Also, since this is a non-clustered index, you could drop and then create the index. REORGANIZE also optimizes internal index and catalog structures. From another point of view. When a clustered index is dropped ONLINE, SQL Server rebuilds the heap two times, once for step 1 and. To "enable", SET to 1. However, ALTER TABLE ignores DATA. Frequency of the maintenance should be considered with the goal of minimizing impact of log generation. The ways I can think around this problems are: 1) set the database to simple recovery mode while you run the reorganize, but you said that isn't acceptableExample #. 13. alter index reorganize 문을 사용하면 작업에서 파일 그룹 내의 다른 파일이 아닌 동일한 파일에만 임시 작업 페이지를 할당할 수 있으므로 인덱스가 포함된 데이터 파일에 사용 가능한 공간이 있어야 합니다. [dbo]. In previous versions of SQL Server, you can use CREATE CLUSTERED COLUMNSTORE INDEX with DROP_EXISTING=ON, or ALTER INDEX (Transact-SQL) and the REBUILD option. 5. Our Production instance is running SQL Server 2014. The DBCC REINDEX command was deprecated in a previous version so it is not as robust as the new ALTER INDEX command is today. Each row is 50 bytes long. You don’t. Select Options under Select a page. ALTER INDEX. For example, consider There are 2 tablesONLINE options in Azure SQL DB, SQL Server 2008+. Reorganize the index. indexes Ok i am confused, i was replacing my "alter index reorganize" part with the "execution dbo. One can also. "cannot be reorganized because page level locking is disabled" means (in sys. This means you will need less free space in your user database during an index rebuild operation and more free space in tempdb. The first part of this tip focuses on SQL Server Enterprise Edition to reduce the duration for index maintenance for off-line rebuilds. REORGANIZE index. Select Allow online DML processing, and then select True from the list. This job needs to be scheduled and ran on a weekly basis due to large data. Parallel index execution and the MAXDOP index option apply to the. . Our Production instance is running SQL Server 2014. If the clustered index is being rebuilt, an exclusive table lock is held. The drawback in this. This query creates the necessary ALTER INDEX statements to correct the. Generates the error…. It defragments the leaf level of clustered and nonclustered indexes on tables and views by physically reordering the leaf-level pages to match the logical, left to right, order of the leaf nodes. In Object Explorer, connect to an instance of Database Engine. By doing the index with ONLINE=ON, you should be able to minimize blocking. gif」の説明 図「alter_index_partitioning. ----- This article - Optimize index maintenance to improve query performance and reduce resource consumption helps you decide when and how to perform index maintenance. 1. Everything is the same - configuration, CPU, RAM, disk drive layout, similar (but not the same) database with similar data and workload. Note: One thing ALTER INDEX does not allow you to do is change the set of columns that comprises the. and even. Alter Index in PostgreSQL, Oracle, SQL Server. . If you need to modify the properties of an index or reorganize or rebuild an index, you can use ALTER INDEX as follows. indexstats. Document table. In SQL Server, you can use ALTER INDEX with the REORGANIZE or REBUILD option. The MAXDOP index option cannot be specified in the ALTER INDEX (. 常にオンラインで実行されます。 つまり、alter index reorganize トランザクション中は、長期にわたって他をブロックするテーブル ロックは保持されず、基になるテーブルへのクエリまたは更新を続行できます。 無効なインデックスに対しては指定できません。 Open Object Explorer & expand the database containing the table you wish to reorganize. There is more functionality in the ALTER INDEX than the DBCC REINDEX commands:This means long-term object-level locks are not held and queries or updates to the underlying table can continue during the ALTER INDEX. Nonclustered index A contains 1 million rows. You may try. The advantage of this statement should let users query full-text indexes while running, but there is a price: depending on the amount of data that has to be treated, it can take some time to complete and hence introduce some undesired events. Not specifying ONLINE option runs the script with the default value OFF. See this blog post for details. table1 REBUILD WITH (ONLINE=ON ,SORT_IN_TEMPDB =. Unlike REORGANIZE on user tables, REORGANIZE on a queue is always performed as an offline operation because page level locks are explicitly disabled on queues. ALTER INDEX . When I run alter index index [IndexName] on dbo. It is also recommended to read the previous article of this series - Rebuild Index Task before reading this one. More specifically deletes are reflected in the deleted bitmap, which the engine joins with the data and returns the rows visible to your transaction. #1637994. regarding reorganize - there is an exception to this - if you have columnstore indexes that are frequently subject to deletions or that are subject on inserts in small batches then running reorg. And if the reorganize is a deadlock. The Query Optimizer does not update statistics after DBCC INDEXDEFRAG or ALTER INDEX REORGANIZE operations. This results in a short reorganization maintenance window. To reduce the number of fragments, reorganize the full-text catalog by using the REORGANIZE option of the ALTER FULLTEXT CATALOGTransact-SQL statement. PS C:> Invoke-DbaDbShrink -SqlInstance sql2014 -Database AdventureWorks2014 -PercentFreeSpace 50 -FileType Data -StepSize 25MB. Add B-tree nonclustered indexes for efficient table seeks. The operation can also be interrupted without losing work already completed. Expand the table on which you want to reorganize an index. The total fragmentation value will be displayed. sqlの「create index」または「alter table」を使うことで、データベースのテーブルにインデックス（index）を付与することができます。sqlの「create index」または「alter table」を使うことで、テーブルのインデックス（index）を削除することができます。Alter EVENT SESSION [XeMerge] ON SERVER State = START. DECLARE @Sql NVARCHAR (5000) = N'ALTER INDEX ' + @indexName + N' ON ' + @tableName + N' REORGANIZE'; EXEC sp_executesql @Sql. Listing 14-7 Syntax for a Columnstore Reorganize Operation. SQL: Procedure for rebuild and reorganize indexes like Microsoft says. ) Then rerun the above free-space query again to see how the shrink worked: Free space after. Change the index option settings. When you insert, update, delete, merge, etc. x) and SQL Server 2014 (12. ALTER INDEX [XPKItem] ON [dbo]. This statement essentially merges all the fragments. It rebuilds a spatial index or a specified partition of a partitioned index. • DROP INDEX only when the user drops a non-clustered index. [myTable] REORGANIZE WITH ( LOB_COMPACTION = ON ) I have the above query running for 16 days (still running), the table is a dummy table used for benchmark tests, it has over 10 Billion rows. [BeerFilter_FloatTable] REORGANIZE . The Rebuild Index Task uses the ALTER INDEX statement. x) de y en Azure SQL Database, se recomienda usar ALTER INDEX REORGANIZE en lugar de ALTER INDEX REBUILD para los índices de almacén de columnas. I need to change the default value for the ONLINE option of almost all of the indexes to ON so that rebuilding an indexes with this script: ALTER INDEX [Index1]|ALL ON [Table1] REBUILD; will do the same as: ALTER INDEX [Index1]|ALL ON [Table1] REBUILD WITH (ONLINE = ON); I have to do it without recreating the indexes. REORGANIZE) will NOT update statistics at all, because it only sees a few pages of the index at a time. e. Before you execute the query you can disable the background tuple mover task by using the trace flag 634. Because there are so many of them running at a time (each in a different database), and they are going parallel (which ties up even more workers), everything piles up.