http://www.kennygorman.com/wordpress/?p=1270

몽고DB 프로파일링 하는 설명과, 구문 튜닝 등등 튜닝 기법 소개 

Parallel Query Execution.pdf

http://blogs.msdn.com/b/psssql/archive/2012/12/21/uneven-query-executions-with-parallelism.aspx

※ 2013.02.18

주디아줌마) 병렬로 풀리더라도 아래와 같은 몇가지 이슈가 나오면 시리얼 플랜으로 풀린다.

Forcing a Parallel Query Execution Plan

http://sqlblog.com/blogs/paul_white/archive/2011/12/23/forcing-a-parallel-query-execution-plan.aspx

기존 SQL을 mongoDB Query로 변환해주는 툴이 있네요^^

http://www.querymongo.com/

원본 링크 : http://searchsqlserver.techtarget.com/feature/Trace-flags

Skip Startup Stored Procedures (4022) : 시작 프로시져를 스킵

This is a handy trace flag for troubleshooting. It forces SQL Server to skip startup stored procedures. This is especially useful if a stored procedure has been altered and causes harm to your system. After you set this trace flag, you can then debug the stored procedure and set it back to its original state.

Ignore All Index Hints (8602) 모든 인덱스 힌트를 무시 

Trace flag 8602 is a commonly used trace flag to ignore index hints that are specified in a query or stored procedure. This is a fantastic option when you're trying to determine if an index hint is hurting more than helping. Rather than rewriting the query, you can disable the hint using this trace flag and rerun the query to determine if SQL Server is handling the index selection better than the index hint.

Disable Locking Hints (8755) 락 힌트를 비활성화

Trace flag 8755 will disable any locking hints like READONLY. By setting this, you allow SQL Server to dynamically select the best locking hint for the query. If you feel the query's locking hint may be hurting performance, you can disable it and rerun the query.

Disable All Other Hints (8722) 모든 힌트를 비활성화

Lastly, the 8722 trace flag will disable all other types of hints. This includes the OPTION clause.

원본 링크  : http://www.sqlservergeeks.com/blogs/AmitBansal/sql-server-bi/663/sql-server-did-you-know-about-trace-flag-4136

So what about Trace Flag 4136 ? 

(Microsoft SQL Server 2008 R2 Cumulative Update 2, SQL Server 2008 Service Pack 1 (SP1) Cumulative Update 7 and Microsoft SQL Server 2005 Service Pack 3 (SP3) Cumulative Update 9 introduce trace flag 4136)

While OPTIMIZE FOR UNKNOWN disables parameter sniffing at query level, trace flag 4136 disables parameter sniffing at instance level. Which means, no parameter sniffing for that instance – all queries/workloads for all databases get affected with this.

trace 8649
http://connect.microsoft.com/SQLServer/feedback/details/714968/provide-a-hint-to-force-generation-of-a-parallel-plan

Identifying Hot and Cold Data in Main-Memory Databases

파일 링크 http://research.microsoft.com/pubs/176690/ColdDataClassification-icde2013-cr.pdf

Main memories are becoming sufficiently large that most OLTP databases can be stored entirely in main memory, but this may not be the best solution. OLTP workloads typically exhibit skewed access patterns where some records are hot (frequently accessed) but many records are cold (infrequently or never accessed). It is more economical to store the coldest records on secondary storage such as flash. As a first step towards managing cold data in databases optimized for main memory we investigate how to efficiently identify hot and cold data. We propose to log record accesses – possibly only a sample to reduce overhead – and perform offline analysis to estimate record access frequencies. We present four estimation algorithms based on exponential smoothing and experimentally evaluate their efficiency and accuracy. We find that exponential smoothing produces very accurate estimates, leading to higher hit rates than the best caching techniques. Our most efficient algorithm is able to analyze a log of 1B accesses in sub-second time on a workstation-class machine.

정말 참석해보고 싶었던 TechPlanet이었습니다. 다행이도 동영상으로 공유되어서 정말 행복합니다.

• New SQL trends- how MariaDB/SkySQL make it happen : Colin Charles/Chief Evangelist, Monty program Ab
• MongoDB, Redis, MySQL과 함께하는 모바일 앱 로그 수집 및 통계 시스템 : 박현우/CTO, 스마트스터디