Large tables should be in their own full-text catalog. Rebuilding an index means that a whole new set of pages is allocated for it. Object: SQLServer:Databases; Counter: Percent Log Used ; Instance: (your big database name) Alert if counter rises above: 80; Response: Execute job ('Reorganize Check') Create a job ('Reorganize Check') Rebuilding a clustered columnstore index is an offline operation until SQL Server 2019 when the ability to rebuild online was introduced. I know the sql to perform this action on all indexes in a table is. Since you issued a REBUILD and not a REORG, cancelling the query will result in a rollback which will take even more time. However, you can create a staging table insert all rows into that, drop original table and rename staging table to original. the year and month columns. OBJECT_ID) AS TableName, ind. Index automation Job script. August 21, 2010 at 11:54 pm. Default SQL Server value is 0 or 100%, which means that no free space should be left on each page. In Object Explorer, click the plus sign to expand the database that contains the table on which you want to specify an index's fill factor. Yes, rebuilding indexes will take a toll on your transaction log file. I have an index on a . (About 1 TB of data including myIndex (non. Rebuilds are generally faster. On the Table Designer menu, click Indexes/Keys. This index always show 100% avg_fragmentation_in_percent, index level 2, pages =8. To reorganize index SQL Server, right-click it & choose Reorganize. The import process should be reworked to bulk-load one table at a time. The fully qualified name or alias in the form: schema. This REBUILD option is available in SQL Server 2008 onwards. 4) Move database back to full recovery mode. All they do is waste space and resources. Just go to the table, further expand the indexing folder and right after that you can right-click on it and select the option to rebuild all the indexes. Index maintenance usually starts 3 hours before the database full backup and ends before the full backup start. So stay tuned as we should have a follow up post soon on his findings and recommendations for. Any full-text indexes of non-trivial size with fragmentation of at least 10% will be flagged to be re-built by our over-night maintenance. There's a general consensus that you should reorganize ("defragment") your indices as soon as index fragmentation reaches more than 5 (sometimes 10%), and you should. Well, I’d wager some of it is backwards compatibility. That's why as a rule of thumb, for fragmentation greater than about 30%. However, the meaning of those operations is different in the case of Columnstore. If you cancel a rebuild operation midway, it. Right-click the index that you want to rebuild online and select Properties. [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. The length of time the rebuild takes is related to the size of the index, not the amount of fragmentation in it. Recommend 7 or less. Points: 1004494. RCSI utilizes tempdb heavily but gives performance boost. Last weekend the index maintenance took more than 5 hours and the full backup was running at the same time. 例えば、10 % 以上 30 % 未満であれば再構成 (Reorganize)、 30% 以上であれば再構築 (Rebuild) するとすれば、. I am a new DBA to a SQL 2005 production Report server. Reorg the Indexes if the Fragmentation level is > 5% and <30%. To add to this, you need to learn your system and how it's used. dm_db_index_physical_stats) is <1000 you don't need to rebuild or reorganize such. FullTextIndexOptimize. You can do maintenance in phases, where each maintenance phase covers a subset of. Select the Update Statistics maintenance task from the list of tasks. If you look into the sys. Select “reorganize index” and “rebuild index. Creating a SQL Server Maintenance Plan. As part of query execution, the Full-Text Engine might receive input from the thesaurus and stoplist. : 15% com. Select Allow online DML processing, and then select True from the list. But if you need to change something about an index (that. This procedure automatically chooses whether to rebuild or reorganize an index according to its fragmentation level, amongst other parameters, and update statistics. This procedure automatically chooses whether to rebuild or reorganize an index according to its fragmentation level, amongst other parameters, and update statistics. Values: - 0: The script will reorganize or rebuild the fragmented indexes. SQL 2012, massive bulk insert into “daily” (heap) table with PAGE compression (~100 GB, ~600 mio rows), create the nonclustered columnstore index (no other indexes on the table), partition switch into main (heap) table. If the index you wish to reorganize is not listed in the “Indexes to be reorganized” section, ensure that it has been added to this section and then click the “OK” button. Offline Rebuilding: This is faster but makes the database unavailable for the duration of the operation. Hallengren website has an option to reorganize indexes say with 5% Fragmentation, and rebuild for 30% Fragmentation. avg_fragmentation_in_percent FROM sys. Click the plus sign to expand the Tables folder. Recall the paper example from above: a rebuild would be like reprinting the document in the correct order and trashing the old ones. Under Select a page, select Options. ”. . Rebuild Index. To reorganize the indexes and table in the database, run the appropriate command that is based on your requirement: To reorganize the tables with an asterisk in the last column, run the following command: db2 reorg table table_name. x) および SQL Server 2014 (12. This issue can be solved by reorganizing or rebuilding the index. We would like to show you a description here but the site won’t allow us. We check the time for sample select query - it was 2s just after index creation. In the official SQL Server documentation, Microsoft advises about the best method for removing index fragmentation in SQL Server as per below: When you have an index. Someone else set it up. To solve this, I want to use the REORGANIZE operation every time. Server Configuration: MS SQL Server 2008 Enterprise Windows Server. For a dedicated SQL pool table with an ordered CCI, ALTER INDEX REBUILD will re-sort the data using tempdb. As visible in the above image, REBUILD and REORGANIZE are the two available choices to play out the trim operation over the page. 2. failed with the following error: "The index "SpatialIndex-20180705-165942" on table "extended_index_113435478_384000" cannot be reorganized because page level locking is disabled. USE AdventureWorks; GO ALTER INDEX ALL ON Production. The easiest way to reorganize an index is to simply drop and recreate the index using the DROP and CREATE INDEX commands. You can still run the index reorg/rebuild as part of your maintenance scripts. From Rebuild or Reorganize: SQL Server Index Maintenance by Kendra Little: Short version: Rebuild: An index ‘rebuild’ creates a fresh, sparkling new structure for the index. Here is a simple query to check fragmentation on your existing indexes:1 Answer. It cames in two flavours: online and offline. On the Standard bar, click New Query. Right-click the Maintenance Plans folder and select New Maintenance Plan. However, reorganizing can be a "more online" operation and is sometimes preferred, even for. Defining "Index Stats Options" as well has become available in SSMS. If you are using Windows Internal Database, you will need to use the sqlcmd utility, which can be. But commit your whole transaction before reorganize. SQL Server development version and Enterprise version has option ONLINE, which can be turned on when Index is rebuilt. For applications requiring continuous availability, the online option is advisable. [Test] REBUILD WITH (ONLINE = ON); Additionally, I would only rebuild indexes which require it. Larger indexes have more intermediate levels and pages. below line will remove the NULL value from the query. Reorganizing tries to put the leaf level of the index back in logical order within the pages that are already allocated to the index. Scale back down once the index rebuild is complete. Any full-text indexes of non-trivial size with fragmentation of at least 10% will be flagged to be re-built by our over-night maintenance. You can also see if a reorganize will help until you can do a full rebuild. For instance, in the Maintenance Plans of SQL Server 2017, it is possible to rebuild only those indexes where fragmentation level is higher than a specific percentage and has more pages than specified in "Page Count". Expand Tables. Create a maintenance plan. " failed with the following error: "Transaction (Process ID 94) was deadlocked on lock resources with another process and has. For more information, see sys. The Full-Text Engine in SQL Server is fully integrated with the query processor. RESUMABLE = ON means you can pause. – HABO. There are some good reasons to Rebuild an index, like updating statistics. Users(DisplayName) WITH (ONLINE = ON, RESUMABLE = ON, MAX_DURATION = 1); Those parameters mean: ONLINE = ON means you’ve got the money for Enterprise Edition. It also enables faster growth in the future. For example, we have a set of tables that support an application. It may also take longer to REORGANIZE a highly fragmented index than to REBUILD it. Particularly if you are in full recovery. SELECT a. There are two ways of doing that: (i) by using the ‘ DBCC SHOWCONTIG ‘ command, and (ii) by using the ‘ sys. Using SQL Server Management Studio: In the Object Explorer pane navigate to and expand the SQL Server, and then the Databases node Expand the specific database with fragmented index Expand the. Fragmentation. The first part of this tip focuses on SQL Server Enterprise Edition to reduce the duration for index maintenance for off-line rebuilds. Index reorg only shuffles around leaf-level pages of your index and will try to compact those - but it doesn't completely rebuild the index structure. Index Rebuild operation first drops and then recreates the index. The procedure uses SQL Server ALTER INDEX command, with the REORGANIZE option NULL. Use the page count reported by DBCC SHOWCONTIG to get an idea of the size of the indexes (each page is 8 KB in size). You can read more on rebuilding indexes here . I cannot understand the reason, can you ?. Index Rebuild vs Index Reorganize. Select the Compact large object column data checkbox to specify that all pages that contain large object (LOB) data are also compacted. For more information, see ALTER INDEX (Transact-SQL). One time job to reorganize the indexes One time job to rebuild the indexes Scheduling ongoing reorganization job SQL databases, similar to the file system on a disk, will fragment over time. USE AdventureWorks; GO ALTER INDEX ALL ON Production. If you don’t spend much time with SQL Server and you. Right-click the table on which the full-text index is defined, select Full-Text index, and on the Full-Text index context menu, select Properties. Expand the Indexes. In SQL Server, when rebuilding an index which previously had statistics updated with PERSIST_SAMPLE_PERCENT, the persisted sample percent is reset back to default. 1) Since its indexes are not reorganized before. Rebuild or Reorganize SQL Index. dm_db_index_physical_stats (under the Examples -> D section: Using sys. Depending on the type of index and the Database Engine version, a rebuild operation can be done offline or online. Select “reorganize index” and “rebuild index. [FactInternetSales] REBUILD PARTITION = ALL WITH (PAD_INDEX = ON, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, ONLINE = OFF,. Next the New Job window will open. You can still run the index reorg/rebuild as part of your maintenance scripts. If not specified otherwise, the procedure uses the fill factor that is already set for each index. Heaptest default values go 50 select. We are aware that we. Here is the image for additional clarity. From all the research I've done, I can't really find any indication of why you would want page fullness to be low, and am anticipating that I'll want to do an index reorganize operation to set the value to. ALTER INDEX index_name ON table_name REBUILD -- REORGANIZE. Are there any advantages or disadvantages to using " UPDATE STATISTICS (Index name) " as opposed to "ALTER INDEX (index. Total fragmentation is 96% page fullness 66%, avg row size is 20,. Add a comment. For a table with an ordered clustered columnstore index, ALTER. According to Microsoft’s best practices, it is recommended to reorganize indexes if their fragmentation level is >15% and <=30% (if >30%, a rebuild should be done). Similarly, removing. . The query causing the block is in the format: ALTER INDEX [indexName] ON tableName REORGANIZE. It defragments the leaf level of clustered and non-clustered indexes on tables and views by physically reordering the. The reason we want to load. Right-click Maintenance Plan and select Execute. 100% complete End Progress Error: 2016-06-10 22:30:23. Mohamad Mahmoud Darwish. If you choose to compact large object data, the statement uses the. You cannot say, “If the index is 45% or more fragmented, rebuild it– otherwise do nothing. 7. For more information, see CREATE INDEX (Transact-SQL). A more intelligent way is to check fragmentation first then rebuild or reorganise. The performance benefit may not be noticeable for indexes that are used primarily for seek operations. Because this is an online operation, the index is available while the statement is running. In this article, we will go through these new. No right from SQL Server 7. Rename. That can be found using the STATS_DATE function. These pages can get empty space on them and become out of order over time as well. ;WITH cte AS ( SELECT object_id, index_id, partition_number, rows, ROW_NUMBER () OVER (PARTITION BY object_id, index_id, partition_number. . Hi, Added an index maintenance job (Hallengren) to a database (SQL Server 2016) with a few large tables. You can go the easy way and use SQL Server Maintenance Plans, but unfortunately they’re very simplistic: you can only say “rebuild all the indexes” or “reorganize all the indexes”. First, we will start the index reorganization in a session using the following T-SQL code. The REORGANIZE modifier for ALTER INDEX is not currently supported by Azure SQL. 2. @OnlyModifiedStatistics = 'Y'. Hi Everyone, We have a weekly maintenance plan in place that fails with the following error: Executing the query "ALTER INDEX [NCI_WI_BId_PId_PMId_SId_NPB] ON [Infr. The REINDEX command requires an exclusive table lock, which means that it'll stall any accesses to the table until the command has completed. Create a job to run your index reorganize ('Reorganize'). Is this possible to do? In earlier versions of Microsoft SQL Server it could cause system slowdown to reorganize or rebuild a large index. For us to perform this test we will first create a simple test table with a few columns and load a fair amount of data into it. Now. Basically, an index rebuild copies the index to another place. If not specified otherwise, the procedure uses the fill factor that is already set for each index. 1. In this article. This article introduces the concept of fragmentation and discusses two ways of managing index fragmentation - reorganizing and rebuilding. Step 1. ) Index Size is greater than 5 MB's. Categorize fragmentation percentage – Microsoft suggests that we. object_id =. you are reading your query result incorrect. create table dbo. SQL Agent doesn't connect as SA, and the rebuild index task generates a command that looks like ALTER INDEX [ci_FactInternetSales] ON [dbo]. Too many full-text index fragments in the full-text index, can lead to substantial degradation in query performance. When rebuilding offline your index is completely unavailable, but the operation is faster than that online. Microsoft's guidance on index reorganize and rebuild supports this: For example, if a given index is used mainly for scan operations, removing fragmentation can improve performance of these operations. This is quite a big problem in SQL Server, as your indexes will fragment over time. Rebuild/Reorganize working fine. Script to reorganize all indexes on all tables in user databases. - the index depth is more then 4 levels. REORG INDEXES/INDEXES command reorganizes indexes. My problem is that the reorg is running for a very long time. 3. ), which reorganizes all the indexes on the. If the index’s design or your SQL Server edition doesn’t allow for that, it’ll perform the last resort – an offline index rebuild. [Test] REBUILD WITH (ONLINE = ON); Additionally, I would only rebuild indexes which require it. The database is using the Simple Recovery model. It checks the SQL Server licences, if Enterprise it will rebuild the index online else it. dm_db_index_physical_stats function is the preferred tool to use to check index fragmentation on any CA or DA database table. In SSMS, expand the Kids1 table and right click on Indexes, select New Index and click on Non-Clustered Columnstore Index as shown below. where, table_name is the name of the table to be reorganized. Reorganizing an index uses minimal system resources. 2. If you what you are saying is true, even reorganizing the indexes that have never been, may. Rebuilding indexes only does the index itself so the column stats are stale unless they hit the "20% data change + 500 records" criteria to trigger the auto-update. Starting from SQL Server 2016, new options were added to the index maintenance tasks that allow us to perform the Rebuild Index and Reorganize Index tasks, based on the fragmentation percentage of the index, and other useful options to control the index maintenance process. #1162454. Bulk amount records are deleted and updated frequently. The default value for this parameter will be ‘CATALOG’. 4. Index Rebuild vs Index Reorganize. To run the Maintenance plan, make sure your SQL server agent service is running. Therefore, you do not need to update statistics after performing ALTER INDEX REBUILD, DBCC DBREINDEX, DBCC INDEXDEFRAG, or ALTER INDEX REORGANIZE operations. EventID, MAX (b. Your disk drive space is for files, not for ornamentation. To update all statistics in a table. In this article. It has been my understanding that REORGANIZEing an index should not interfere with other operations (that is, it. This can be checked using:. Under the very wrong assumption that it wouldn't take long, I've ran ALTER INDEX ALL ON OUR_BIGGEST_TABLE REORGANIZE;. The SQL Server Maintenance Solution lets you intelligently rebuild or reorganize only the indexes that are fragmented. This topic provides. 2. If you're looking for whenif the index was ever rebuilt, the Ola sp does have the ability to log to a table and the previous DBA hopefully utilized this feature. Use the Rebuild Index Task dialog to re-create the indexes on the tables in the database with a new fill factor. This would also keep the original order of columns. To work around this, try the following methods: Method 1 ( recommended ): Limit the number of full-text indexes in the same catalog. You don’t get bonused based on the amount of free space on your drives. Click Next, and you can define the Update Statistics task. However I want advice whether it is required to setup the SQL Server Index and Statistics Maintenance scripts, because my SQL server is running on a SAN infrastructure and I have read that there is no benefit to setting fill-factor to less than 100%, or to perform index. It drops index entirely and creates it from scratch. The log size shouldn't be unrestricted. Best regards,. The execute sql task should contain the index rebuild code along with stats rebuild . Many people (and even solutions) in the SQL Server community say you need to look at Index Fragmentation levels (e. indexes ind ON ind. Expand the Indexes folder. Rebuilding a clustered columnstore index is an offline operation until SQL Server 2019 when the ability to rebuild online was introduced. Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) Convert a rowstore table to a clustered columnstore index, or create a nonclustered columnstore index. [Subscribers] REBUILD GO Rebuilding all indexes in a table USE [SQLMaestros] GO ALTER INDEX ALL ON [hol]. On the right panel, right-click SQL Server Agent. The syntax for rebuilding indexes is very simple, we just add the "WITH ONLINE=ON" clause to the ALTER INDEX command. The detailed information can also be useful to determine whether your dedicated SQL pool is being impacted by a large number of small, fragmented tables, which can lead to delays in compilation. 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. You need to assemble the SQL prior to calling SP_ExecuteSQL, i. -- Compute fragmentation information for all full-text indexes on the database SELECT c. SQL Server does not maintain when an Index was last rebuild, instead it keeps information when stats were last updated. The documentation is also indicating that: Online index operations are not available in every SQL Server edition. Also trying to avoid logging to transaction log and log. Fair enough, but let’s make some adjustments. SQL Server ALTER INDEX Syntax. 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. The procedure uses SQL Server ALTER INDEX command, with the REORGANIZE option NULL. On the Define Reorganize Index Task page, select the server or servers where you'll be moving index pages into a more efficient search. Create an agent WMI alert ('Reorganize Relief Valve') on a performance condition. I was going to take a look at Ola Hallengren's scripts and some other stuff but wanted to see if there was possibly a simple explanation for this. Next time it runs slow, check out how fragmented the clustered and non clustered indexes are, and also check to see if you have AUTO_UPDATE Stats enabled!I would suggest that you use Ola Hallengren's scripts, freely available and widely used. set @SQL = 'alter index ' + QuoteName ( @IndexName ) + ' on ' + QuoteName ( @TableName ) + ' rebuild';. SQL Server Index Rebuild and Reorganize Script. You can safely stop it but you need to find out why your database became slow. It is compatible with all versions of SQL Server 2005 , 2008 , 2012 , 2014 and 2016. Note In SQL Server 2012 (11. These options define how much. I'm just using the reorg index task that is in the maintenance plan designer GUI. In the New Maintenance Plan dialog box, in the Name box, type a name for the plan and select OK. Here is the image for additional clarity. If you want to know how far along it is, open up another instance of SSMS and connect to the server, then run a query against the sys. Bad internal fragmentation (having lots of free space on the pages) means the index is bigger than it needs to be. 2. Another possibly is that the index is being rebuilt and then re-fragmenting again. Index Reorganize During Database Full Backup. This is a powerful feature that you can use to your advantage. e. This means loading the table and building all nonclustered indexes before moving on to the next one. 2) - this is where it might seem you "solved" the problem with index rebuild, but index rebuild could rather be consequence for better, more tailored execution plan for the problematic query/queries. Reorganizing queue indexes. It reorgs indexes when fragmentation is below 30% else it rebuild the index. The maintenance plan. 3番目のパラメータは、Non ClusteredインデックスID（sys. This method can help when. First it’ll try an index reorganize, which is an online operation. Microsoft recommends Index Rebuild operation to defrag indexes if the fragmentation level of your index is greater. index_id > 0 -. Click the plus sign to expand the table on which you want to rebuild an index online. 4) Move database back to full recovery mode. Index rebuilding and reorganizing are the two methods to maintain indexes and improve database performance. Monitor tempdb during rebuild operations. If a nonclustered index is being rebuilt, a shared lock is held on the table in question during the operation. Select Maximum degree of parallelism, and then enter some value between 1. Add a comment. This tool provides index analysis to manage index defragmentation, including rebuild and reorganize fragmented indexes . Locking. For now, I have just turned off the weekly index reorganize task which is not really a good long term solution. So, whenever I need to rebuild the indexes of my OrdersItemstable, with some millions of rows, my customers can't create/edit new orders for about 2-4 minutes. REORGANIZE. The query result is matched against the full-text index. DROP INDEX when you are dropping a clustered index offline without specifying the MOVE TO clause and nonclustered indexes do not exist. For maintenance i create a procedure that: -Shrink Database file (if is enabled) -Shrink Database log file. LDAP_ENTRY. I was going to take a look at Ola Hallengren's scripts and some other stuff but wanted to see if there was possibly a simple explanation for this. The “Reorganize” index option is more facilitated than the “Rebuilt” index. The following index operations require no additional disk space: ALTER INDEX REORGANIZE; however, log space is required. The first item is "Reorganize data and index pages". SELECT total_execution_time, percent_complete, name,state_desc,last_pause_time,page_count FROM sys. Follow. The table can be in a local or a remote database. Expand the Indexes folder. table-name must be used. When using columnstore indexes, the delta store may end up with multiple small row groups after inserting, updating, and. In this example, the code creates a daily SQL Agent job that runs at 23:30 (11:30 p. Use ALTER INDEX REORGANIZE, the replacement for DBCC INDEXDEFRAG, to reorder the leaf level pages of the index in a logical order. Rename. Burt King. 1. Designing efficient indexes is paramount to achieving good database and application performance. No, there is no auto-magical defragging of indexes. Reorganizing an index uses minimal system resources. ALTER INDEX ALL ON table_name REORGANIZE OR. To rebuild an index means to create anew one, then drop the old one. There are two options to fix fragmentation. Reorganize a fragmented SQL Server index and optimize performance. Reorganize or rebuild an index SQL Server Management Studio. To estimate the duration of the REORGANIZE DATABASE you can use the SQL statement from the "Step 1" section in the attached "REORGANIZE estimator" . x) and in Azure SQL Database, we recommend using ALTER INDEX REORGANIZE instead of ALTER INDEX REBUILD for. Reorganizing an index only deals with the fragmentation that exists, and the more fragmentation there is, the longer a reorganize will take. Problem. For more information, see the article: Gathering SQL Server indexes statistics and usage information. On the Table Designer menu, click Indexes/Keys. It was trying to do so because when Index is REBUILT (with. Dec 19, 2021, 9:55 PM. The first rebuilds a single index on a table and the second rebuilds all the indexes on the table. Thank you, ShamAnswers. As with a B-tree index, the rebuild will create a brand new columnstore index from the underlying data. Everything is the same - configuration, CPU, RAM, disk drive layout, similar (but not the same) database with similar data and workload. ALTER INDEX ALL ON table_name REBUILD OR. In Object Explorer, click the plus sign to expand the database that contains the table on which you want to specify an index's fill factor. g. Rebuilds are generally faster. We leave default values here as well. August 1, 2013 at 3:52 pm. 3. g. Thank you all for your suggestions. Product REBUILD. This opens the Toolbox and the maintenance_plan_name [Design] surface with the Subplan_1 subplan. 2. #1637994. deteriorating. ALTER INDEX ALL ON [dbo]. Use the ReorganizeIndex Task dialog to move index pages into a more efficient search order. dm_db_index_physical_stats to get information about your index fragmentation (see the avg_fragmentation_in_percent column). 0 databases. These are two different modes to remove index fragmentation. It is recommended to use an integer data type in the index. The. Just go to the table, further expand the indexing folder and right after that you can right-click on it and select the option to rebuild all the indexes. index rebuild/reorganize frequency. This means long-term object-level locks are not held and queries or updates to the underlying table can continue during the ALTER INDEX. A clustered index's key columns are called a clustering key. I have been advised by a contracted SQL Server expert that, after any change in # of CPUs and/or available memory, I should reorganize all indexes and then update all statistics or SQL Server will not make the full use of the new resources. Product REBUILD GO Index Reorganize : This process physically reorganizes the leaf nodes of the index. Specify the. REBUILD will not just rebuild index, but also force update of corresponding statistics. before i answer your question is the database on simple recovery. Hi Team, Today when I go through some of the SQL Server performance videos, found one interesting video (Please find the link below), where he said that rebuilding indexes is a very expensive thing and it will clear the cache every time an index rebuild happens, (It means that we indirectly killing the SQL Server everything we rebuild.