2 de Diciembre #SqlSaturdayMontevideo

Transcription

1 2 de Diciembre 2017 #SqlSaturdayMontevideo

2 Patrocinadores del SQL Saturday 3 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

3 Javier Villegas DBA Manager at Mediterranean Shipping Company (MSC) Microsoft MVP Data Platform Involved with the Microsoft SQL Server since SQL Server 6.5 MCP and MCTS Blogger and MSDN Forums contributor Specialization in SQL Server Administration, Performance Tuning and High Availability Frequent Speaker at NetConf, SQL Saturdays, 24 HOP and PASS Virtual /12/2017 SQL Saturday #691 Montevideo, Uruguay

4 SQL Server 2017 Mejoras Impulsadas por la comunidad 5 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

5 Agenda Introduction Smart Differential Backup Smart Transaction Log Backup SELECT INTO. ON Filegroup Tempdb Setup improvements Tempdb monitoring and planning Transaction log monitoring and diagnostics Improved backup performance for small databases on high-end servers Processor information in sys.dm_os_sys_info Capturing Query Store runtime statistics in DBCC CLONEDATABASE Resumable Online Index Rebuild Automatic plan correction 6 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

6 Heterogenous environments Multiple data types { } Different development languages T-SQL Java C/C++ C#/VB.NET PHP Node.js Python Ruby On-premises, cloud, and hybrid environments 7 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

7 On the platform of your choice SQL Server /12/2017 SQL Saturday #691 Montevideo, Uruguay

8 SQL Server 2017 Supported platforms Linux Containers Windows RedHat Enterprise Linux (RHEL) 7.3 SUSE Enterprise Linux (SLES) v12 SP2 Ubuntu & Possibly other Linux distributions Docker: Windows & Linux containers Windows Server / Windows 10 Windows Server 9 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

9 Introduction Although SQL Server 2016 runs faster, SQL Server 2017 promises to run even faster and empower customers to run smarter with intelligent database features like: - The ability to run advanced analytics using Python in a parallelized and highly scalable way - The ability to store and analyze graph data - Adaptive query processing - Resumable Online indexing - Allow customers to deploy it on the platform of their choice (Windows or Linux) - Docker SQL Server is one of the most popular DBMS among the SQL community and is a preferred choice of RDBMS among customers and ISVs owing to its strong community support In SQL Server 2017, there are several customer delighters and community-driven enhancements based on the learnings and feedback from customers and the community from in-market releases of SQL Server /12/2017 SQL Saturday #691 Montevideo, Uruguay

10 Smart Differential Backup A new column modified_extent_page_count is introduced in sys.dm_db_file_space_usage to track differential changes in each database file of the database. The new column modified_extent_page_count will allow DBAs, the SQL community and backup ISVs to build smart backup solutions, which perform differential backup only if percentage changed pages in the database are below a threshold (say 70 to 80 percent), otherwise full database backup is performed. With a large number of changes in the database, cost and time to complete differential backup is similar to that of full database backup, so there is no real benefit to differential backup in this case; instead, it can increase database restore time. By adding this intelligence to the backup solutions, customers can now save on restore and recovery time while using differential backups /12/2017 SQL Saturday #691 Montevideo, Uruguay

11 Smart Differential Backup Consider a scenario where you previously had a backup plan to take full database backup on weekends and differential backup daily. In this case, if the database is down on Friday, you will need to restore full database backup from Sunday, differential backups from Thursday and then T-log backups of Friday. By leveraging modified_extent_page_count in your backup solution, you can now take full database backup on Sunday and let s say by Wednesday, 90 percent of pages have changed, the backup solution takes full database backup rather than differential backup since the time and resources consumed remain the same. If database is down on Friday, you will restore the full database backup from Wednesday, small differential backup from Thursday and T-log backups from Friday to restore and recover the database much quicker compared with the previous scenario. This feature was requested by customers and community in connect item /12/2017 SQL Saturday #691 Montevideo, Uruguay

12 Smart Differential Backup USE <database-name> GO select CAST(ROUND((modified_extent_page_count*100.0)/allocated_extent_page_count,2) as decimal(2,2)) from sys.dm_db_file_space_usage GO select CAST(ROUND((SUM(modified_extent_page_count)*100.0)/SUM(allocated_extent_page_count),2) as decimal(2,2)) as '% Differential Changes since last backup' from sys.dm_db_file_space_usage GO 13 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

13 Smart Transaction log Backup In the release of SQL Server 2017, a new DMF sys.dm_db_log_stats(database_id) is available, it exposes a new column log_since_last_log_backup_mb. The column log_since_last_log_backup_mb empowers DBAs, the SQL community and backup ISVs to build intelligent T-log backup solutions, which take backup based on the transactional activity on the database. This intelligence in the T-log backup solution will ensure the transaction log size doesn t grow due to a high burst of transactional activity in short time if the T-log backup frequency is too low. It also help avoid situations where default periodic interval for transaction log backup creates too many T-log backup files even when there is no transactional activity on the server adding to the storage, file management and restore overhead /12/2017 SQL Saturday #691 Montevideo, Uruguay

14 SELECT INTO. ON Filegroup One of the highly voted connect items and highly requested feature requests from the SQL community to support loading tables into specified filegroups while using SELECT INTO is now made available in SQL Server 2017 SELECT INTO is commonly used in data warehouse (DW) scenarios for creating intermediate staging tables, and inability to specify filegroup was one of the major pain points to leverage and load tables in filegroups different from the default filegroup of the user loading the table. Starting SQL Server 2017, SELECT INTO T- SQL syntax supports loading a table into a filegroup other than a default filegroup of the user using the ON <Filegroup name> keyword in TSQL syntax shown below: 15 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

15 SELECT INTO. ON Filegroup ALTER DATABASE [AdventureWorksDW2016] ADD FILEGROUP FG2 select * from sys.database_files ALTER DATABASE [AdventureWorksDW2016] ADD FILE ( NAME= 'FG2_Data', FILENAME = 'S:\sql_data\AdventureWorksDW2016_Data1.mdf' ) TO FILEGROUP FG2; GO SELECT * INTO [dbo].[factresellersalesxl] ON FG2 from [dbo].[factresellersales]; 16 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

16 Tempdb setup improvements One of the constant pieces of feedback, the SQL community and the field after doing the SQL Server 2016 setup improvements is to uplift the maximum initial file size restriction of 1 GB for tempdb in setup. For SQL Server 2017, the setup allows initial tempdb file size up to 256 GB (262,144 MB) per file with a warning to customers if the file size is set to a value greater than 1 GB and if Instant File Initialization (IFI) is not enabled. It is important to understand the implication of not enabling instant file initialization (IFI) where setup time can increase exponentially depending on the initial size of tempdb data file specified. IFI is not applicable to transaction log size, so specifying a larger value of transaction log can increase the setup time while starting up tempdb during setup irrespective of the IFI setting for the SQL Server service account /12/2017 SQL Saturday #691 Montevideo, Uruguay

17 Tempdb monitoring and planning The SQL Server Tiger team surveyed the SQL community to identify common challenges experienced by customers with tempdb. Tempdb space planning and monitoring were found to be top challenges experienced by customers with tempdb. As a first step to facilitate tempdb space planning and monitoring, a new performant DMV sys.dm_tran_version_store_space_usage is introduced in SQL Server 2017 to track version store usage per database. This new DMV is useful in monitoring tempdb for version store usage for DBAs who can proactively plan tempdb sizing based on the version store usage requirement per database without any performance toll or overheads of running it on production servers /12/2017 SQL Saturday #691 Montevideo, Uruguay

18 Transaction log monitoring and diagnostics One of the highly voted connect items and highly requested requests from the community is to expose transaction log VLF information in DMV. T-log space issues High VLFs and log shrink issues are some of the common challenges experienced by DBAs. Some of the monitoring ISVs have asked for DMVs to expose VLF information and T-log space usage for monitoring and alerting. A new DMV sys.dm_db_log_info is introduced in SQL Server 2017 to expose the VLF information similar to DBCC LOGINFO to monitor, alert and avert potential T-log issues. In addition to sys.dm_db_log_info, a new DMF sys.dm_db_log_stats(dbid) is released, which expose aggregated transaction log information per database /12/2017 SQL Saturday #691 Montevideo, Uruguay

19 Improved backup performance for small databases on high-end servers After migrating an existing in-market release of SQL Server to high-end servers, customers may experience a slowdown in backup performance when taking backups of small to medium-size databases. This happens as we need to iterate the buffer pool to drain the ongoing I/Os. The backup time is not just the function of database size but also a function of active buffer pool size. In SQL Server 2017, we have optimized the way we drain the ongoing I/Os during backup, resulting in dramatic gains for small to medium-size databases. We have seen more than 100x improvement when taking system database backups on a 2TB machine. More extensive performance testing results on various database sizes is shared below. The performance gain reduces as the database size increases as the pages to backup and backup IO take more time compared with iterating buffer pool. This improvement will help improve the backup performance for customers hosting multiple small databases on a large high-end server with large memory /12/2017 SQL Saturday #691 Montevideo, Uruguay

20 Improved backup performance for small databases on high-end servers 21 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

21 Processor information in sys.dm_os_sys_info Another highly requested feature among customers, ISVs and the SQL community to expose processor information in sys.dm_os_sys_info is released in SQL Server 2017 The new columns allows to programmatically query processor information for the servers hosting SQL Server instance, which is useful in managing large deployments of SQL Server. New columns exposed in sys.dm_os_sys_info DMV are socket_count, core_count, and cores_per_socket /12/2017 SQL Saturday #691 Montevideo, Uruguay

22 Resumable Online Index Rebuild With this feature, you can resume a paused index rebuild operation from where the rebuild operation was paused rather than having to restart the operation at the beginning. In addition, this feature rebuilds indexes using only a small amount of log space. You can use the new feature in the following scenarios: Resume an index rebuild operation after an index rebuild failure, such as after a database failover or after running out of disk space. There is no need to restart the operation from the beginning. This can save a significant amount of time when rebuilding indexes for large tables. Pause an ongoing index rebuild operation and resume it later. For example, you may need to temporarily free up system resources to execute a high priority task or you may have a single maintenance window that is too short to complete the operation for a large index. Instead of aborting the index rebuild process, you can pause the index rebuild operation and resume it later without losing prior progress. Rebuild large indexes without using a lot of log space and have a long-running transaction that blocks other maintenance activities. This helps log truncation and avoid out-of-log errors that are possible for long-running index rebuild operations /12/2017 SQL Saturday #691 Montevideo, Uruguay

23 Resumable Online Index Rebuild ALTER INDEX IDX_2_5 ON [dbo].[a_table02] REBUILD WITH ( RESUMABLE = ON, ONLINE = ON ); SELECT total_execution_time, percent_complete, page_count, object_id,index_id,name,sql_text,last_max_dop_used,partition_number,state,state_desc,start_time,last_pause_time,total_execution_time FROM sys.index_resumable_operations; 24 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

24 Automatic plan correction Automatic plan correction is a new automatic tuning feature in SQL Server 2017 that identifies SQL query plans that are worse than previous one, and fix performance issues by applying previous good plan instead of the regressed one. In some cases, new plan that is chosen might not be better than the previous plans. This is rare situation and might happen if an optimal plan is not included in a list of plans that will be considered as potential candidates. In other cases, SQL Server might choose the best plan for the current T-SQL query, but the selected plan might not be optimal if the same T-SQL queries is executed with different parameter values. In that case, SQL Server might reuse the plan that is compiled and cached after first execution even if the plan is not optimal for the other executions. These problems are known as plan regressions /12/2017 SQL Saturday #691 Montevideo, Uruguay

25 Automatic plan correction If you identify that previous plan had better performance, you might explicitly force SQL Server to use the plan that you identified as optimal for some specific query using sp_force_plan procedure: EXEC = = 1987 As a next step, you can let SQL Server 2017 to automatically correct any plan that regressed. ALTER DATABASE current SET AUTOMATIC_TUNING ( FORCE_LAST_GOOD_PLAN = ON ) 26 02/12/2017 SQL Saturday #691 Montevideo, Uruguay

26 Automatic plan correction ALTER DATABASE current SET AUTOMATIC_TUNING ( FORCE_LAST_GOOD_PLAN = ON ) This statement will turn-on automatic tuning in the current database and instruct SQL Server to force last good plan if it identifies plan performance regression while the current plan is executed. SQL Server 2017 will continuously monitor and analyze plan performance, identify new plans that have worse performance than the previous ones, and force last know good plan as a corrective action. SQL Server 2017 will keep monitoring performance of the forced plan and if it does not help, query will be recompiled. At the end, SQL Server 2017 will release the forced plan because query optimizer component should find optimal plan in the future /12/2017 SQL Saturday #691 Montevideo, Uruguay

27 TRIM String functions Removes the space character char(32) or other specified characters from the start or end of a string TRANSLATE Allows us to perform a one-to-one, single-character substitution in a string CONCAT_WS() Stands for Concatenate with Separator, and is a special form of CONCAT(). The first argument is the separator separates the rest of the arguments. The separator is added between the strings to be concatenated. The separator can be a string, as can the rest of the arguments be. If the separator is NULL, the result is NULL. STRING_AGG Aggregate functions compute a single result from a set of input values. With the prior versions of SQL, string aggregation was possible using T-SQL or CLR, but there was no inbuilt function available for string aggregation, with a separator placed in between the values /12/2017 SQL Saturday #691 Montevideo, Uruguay

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29 Other features Graph Data Processing with SQL Server Showplan enhancements in SQL Server Adaptive Query Processing /12/2017 SQL Saturday #691 Montevideo, Uruguay

30 Preguntas Javier Villegas SQL Server 2017 Mejoras impulsadas por la /12/2017 SQL Saturday #691 Montevideo, Uruguay

31 Gracias!