Extending Your Use of Extended Events

Transcription

1 Extending Your Use of Extended Events An Introduction to Replacing SQL Profiler with Extended Events ABSTRACT: By Andy McDermid & Sivakumar Thangavelu September 2014 The much-used Microsoft SQL Profiler is a tool headed toward obsolescence. What options are available once the tool is deprecated? We examine SQL Server Extended Events as a possibility. The similarities and differences between these tools is examined and some practical uses are demonstrated.

2 Extending Your Use of Extended Events: An Introduction to Replacing SQL Profiler with Extended Events

3 content Why Advance to SQL Server Extended Events?... How to Apply Your Knowledge of SQL Profiler to Extended Events... Using SQL Server Extended Events Templates... SQL Profile vs. Extended Events: Compare and Contrast... Conclusion... About Datavail

4 Many people working with enterprise technologies live by the "if it ain't broke, don't fix it," mantra, but when tools become obsolete for instance, Microsoft SQL Profiler we need to either adopt new technologies or explore the use of existing technologies. If your troubleshooting tools and techniques are working and you are using the most current technologies available you need not worry. But, if you are still using SQL Profiler, there are other newer and better options available, namely SQL Extended Events. In SQL Server 2008, managing Extended Events was accessible only by using the Transact-SQL query language. There was no user interface available via the Microsoft SQL Server Management Suite. That's a lousy excuse. An Extended Events user interface has now been around since The newer version is now available, so what's up? We at Datavail don't have a good excuse for delaying and dithering. Just like for you, "if it ain't broke, don't fix it" has been working fine for us. After all, SQL Profiler still works. It's a tried-and-true testing technology that's been around forever. It's quick, comfortable, familiar, and easy to use. But, it's also becoming obsolete. You also stuck with WordPerfect and Windows XP until the bitter end, didn't you? Remember how those relationships ended? Using new tools and technologies is an advantage for you and your organization. New tools exist for a reason: They are a marked improvement over existing technologies. Using new tools proactively translates into increased productivity, decreased down time, and a host of other benefits. You'll find Extended Events easy to configure and use for troubleshooting because it is built on all of the best aspects in Profiler. This basic introduction will show you how you can apply your existing knowledge of SQL Profiler to Extended Events. If you already have a solid grasp of Extended Events, we offer some practical tips for productively working with this infrastructure that may be new to you. How to Apply Your Knowledge of SQL Profiler to Extended Events Everything starts from somewhere. As you'll see, even the Microsoft Server team borrowed heavily from SQL Profiler to build the graphical user interface for Extended Events. One of the best methods we know for learning the new technology is to compare and contrast it to what you're replacing. If you don't know either framework very well, you can't lose by reading further and learning more about these tools you should find it easy to get up to speed. Why Advance to SQL Server Extended Events? Before getting into the nitty-gritty of working with Microsoft SQL Server Extended Events, what is it? Microsoft describes it as "a general event-handling system for server systems." The infrastructure is used to correlate data between systems, such as the SQL Server, or even the operating system and database applications. When there's an issue with the data, you need to know where to look to fix the glitch. Extended Events has been around since 2008, so what took us (OK, not just us, everyone!) so long to get on the Extended Events bandwagon? In SQL Profiler, you are likely familiar with the Default Trace feature. You may have used this to look for root causes after an incident or for grouping recent instance events as part of a health check. By default the trace runs in the background on all instances and the data is collected into five 20MB rollover files (You disable the process using sp_configure. The data is then output. You typically read the default trace data using the command sys.fn_trace_gettable(). Page 1 Extending Your Use of Extended Events: An Introduction to Replacing SQL Profiler with Extended 2014 Datavail, Inc. All rights reserved.

5 With Extended Events, similar functions are available through the System Health Session. It is marginally similar to the Default Trace feature in that both functions run in the background and both collect import metrics useful for troubleshooting and forensics. However the collected data sets are quite a bit different. If you desire an Extended Event session to perform like the system health session, but want the default traces data set, it s not hard to do. Microsoft took care to ensure just about each and every profiler event has a corresponding event in Extended Events. And, in fact, even has provided an out-of-the-box Extended Event template to create an Extended Event session that closely matches Profiler s default trace. Using SQL Server Extended Events Templates There are actually several very useful Extended Events templates you will find immediately useful. With templates, you don't need to struggle to reinvent the proverbial wheel. Activity Tracking, for example is the template that can be used to track the same as that produced by Default Trace. An important caveat for users: this doesn't gather information regarding any security audit events. That task is now handled through using the SQL Server Audit feature. Query Detail Sampling and Query Detail Tracking: This template collects detailed statement and error information. You can use this template to track each statement executed on your system as a result of query batches or stored procedures. You can then track errors to the specific statement that caused them. As with the query batch template, the "sampling" template collects only 20% of the errors, while the "tracking" template collects all the data. Query Wait Statistic: Internal and external wait statistics for individual query statements, batches, and remote procedure calls can be collected using this template. It can also be used to collect the query hash and query plan hash for every statement it tracks. Events are only collected from 20% of the active sessions on the server at any given time. You can change the sampling rate by modifying the filter for a specific event session. Connections Tracking: This template tracks connection activity for a server. Database Log IO Tracking: This template monitors the input/output for database log files on a server by tracking events, including asynchronous IO, database log flushes, file writes, spinlock backoffs LOGFLUSHQ and WRITELOG waits. This template collects data in two ways. Raw data is collected to a ring buffer, and spinlock backoff information is aggregated based on the input buffer sql_text. The session is filtered for a single log file per database. SQL Profile vs. Extended Events: Compare and Contrast Let's look at four ways you can apply Extended Events to specific tasks. Again, we are comparing these methods to how they were executed before using SQL Profiler. Let s review the available templates and Microsoft s own description of their capabilities in Extended Events: Count Query Locks: Used to identify the most lock intensive queries for additional investigation and tuning. Query Batch Sampling and Query Batch Tracking: Collects information that allows you to better to understand query flow. It can also be used to trace errors to those troublesome queries. When using these templates, note that the "sampling" template collects only 20% of errors, while using the "tracking" template collects all the data. Blocking and Deadlocking: Just like in SQL Profiler, Extended Events allows you to you track and capture both the XML Deadlock Graph and the Blocked Process Report. In fact, the XML Deadlock Graph event is likely already being collected on your system since it is included part of the system_health session. The Blocked Process Report is not included in the system_health session (note: it is in SQL 2014) but if you do build an Extended Event Session to include it, remember it works just like the Profiler versions and you ll need to set the blocked process threshold configuration option. Audit Traces: It has never been simple to create an auditing solution via SQL Profiler, but oftentimes it has been a necessity. In recent SQL versions, new features like CDC and SQL Audit have closed the gap so that we may not have to look to a trace-based solution to satisfy an auditing requirement. However, there are still times a trace audit might come in handy if only perhaps for Extending Your Use of Extended Events: An Introduction to Replacing SQL Profiler with Extended Page 2

6 a lightweight look at server activity to meet a short term business requirement. Since Extended Events includes all the functionality of SQL Profiler, it is not difficult to create an audit session including guaranteed zero data loss. And, similar to SQL Profiler, the collected data can be written to a file and copied off-site for archival or later analysis if required. Now you should have a fairly good idea that Extended Events is capable of handling anything and everything we use Profiler to accomplish. SQL Server 2012 SQL Profiler Extended Events Event Count As you might infer from this table, with only a few exceptions, everything in Trace is available in Extended Events. This table also highlights the fact the Extended Events has many more events available for consideration when configuring an Extended Event session to collect information or troubleshoot. Let's look briefly at how these new capabilities can add to our toolbox. Conclusion You should now have some ideas about how to work with Extended Events. This is merely a starting point to help you delve into Extended Events, but it is not comprehensive. In the event you or your staff needs more training or assistance with Extended Events, you may want to contact Datavail. We can help you design custom tools and solutions, or assist with a wide range of other tasks to help your enterprise run more effectively and efficiently. By allowing our experts to tackle these tasks, you free your staff to focus on high-priority, high-value projects. If you'd like to know more about our outsourcing services and how we can help your network operate optimally, please contact Datavail to discuss a custom solution for your enterprise. High Resource Use Trace: With SQL Profiler, a user needed to use a server-side profiler trace to collect the trace data to a file, then move that into a table. The data would eventually need to be grouped on the text column and reads, durations and or CPU values aggregated using a tool of the user's choice, such as ClearTrace, to anonymize distinct predicate values within the text field. In Extended Events, the data can be loaded into the Extended Events viewer for analysis within the SQL Server Management Studio. Here it can be grouped and aggregated on the query_hash column to identify the high-read/frequently executing statements. Aggregating Waits: When a query is submitted, SQL Server tries to execute the query and return the data as fast as possible. However, it s likely that somewhere along the path of execution the query will have to wait on some other resource perhaps disk or CPU resources to become available before it can continue. SQL Server captures these wait types and durations. This kind of data has never been available through SQL Profiler. Since SQL 2005 DBAs have mainly relied on a couple dynamic management views (DMV) to get a glimpse of the wait statistics for a SQL instance. These DMVs provide a snapshot view at the current waits stats or an aggregation of wait stats since the last service start. Extended Events include wait info as an event. So now the DBA has the ability to track the wait statistics specific to a task throughout the duration of the task. Page 3 Extending Your Use of Extended Events: An Introduction to Replacing SQL Profiler with Extended 2014 Datavail, Inc. All rights reserved.

7 BIOGRAPHY Andy McDermid Principal SQL Server DBA for Datavail Andy is a MCITP certified MS SQL DBA who delivers and manages delivery of DBA services to many diverse clients. He enjoys helping his clients by finding and deploying pragmatic and practical solutions for their database issues. Andy is always working to improve and expand his DBA skills and he likes to share the experience via writing. Sivakumar Thangavelu SQL Server DBA for Datavail Siva Thangavelu is a certified MS SQL DBA with more than 9 years of experience in SQL Server database administration and development. He has worked with clients from multiple industries and specializes in performance tuning, SSRS reports development and providing high availability and disaster recovery solutions. Siva enjoys reading and follows several SQL Server related forums and blogs. He also likes to hone his skills by attending many SQL server conferences and summits and presenting on various SQL Server related topics. ABOUT DATAVAIL Datavail Corporation is the largest pureplay provider of remote database administration (DBA) services in North America, offering database design and architecture, administration and 24x7 support. The company specializes in Oracle, Oracle E-Business Suite, Microsoft SQL Server, MySQL, MongoDB, DB2 and SharePoint, and provides flexible on-site/off-site, onshore/offshore service delivery options to meet each customer s unique business needs. CONTACT US General Inquiries: Fax Number: info@datavail.com Corporate Headquarters: Datavail Corporation Ridge Parkway Suite 125 Broomfield, CO Bangalore Office Datavail Infotech Pvt. Ltd Concept Business Park #319/9, 1st floor, Block A Hosur Main Road Bommanahalli, Bangalore Database Operations Control Center: Datavail Infotech Pvt. Ltd 3rd Floor, Unit No. B-3 Ashar IT Park, Road No. 16Z Wagale Estate Thane (West), Thane Direct Telephone Number: Extending Your Use of Extended Events: An Introduction to Replacing SQL Profiler with Extended Page 4

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