SQL Server 2008 Development for Programmers

SQL Server 2008 Development for Programmers(Level 200)Springfield .NET Users GroupJune 28th, 2011Presentation by Adam Hutson

Speaker Bio – Adam HutsonDatabase Developer at Expedia and a freelance developer. 11 year career, mostly on software side, on database side for past couple years. Enjoy learning new development techniques, earning MSSQL certifications, and picking up various web & desktop development side projects. Married 8 yrs & 4 kiddos (B-6y, G-4y, G-2y, & G-5m)Blog: http://adamhutson.com/LinkedIn: http://www.linkedin.com/in/adamhutson

Presentation OverviewReview of CRUD & JOIN basicsDynamic vs. Compiled StatementsIndexes & Execution PlansPerformance IssuesScaling up your DatabasePersonal toolbox, templates, & links

CRUD basicsCreate  INSERT statementsINSERTMyTable(Col1, Col2)VALUES ('a','b')Read  SELECT statementsSELECT Col1, Col2 FROMMyTableUpdate  UPDATE statementsUPDATE MyTable SET Col1 = Col1 + Col1Delete  DELETE statementsDELETEFROMMyTableWHERE Col2 ='b'

JOIN basics[INNER] JOINLEFT [OUTER] JOINRIGHT [OUTER] JOINFULL [OUTER] JOINCROSS JOIN

[INNER] JOININNER Joins combine the matching records from 2 tables. INNER keyword is optional.

LEFT [OUTER] JOINLEFT [OUTER] JOINs combine all the records from the left table and only the matching records from right table. OUTER keyword is optional.

RIGHT [OUTER] JOINRIGHT [OUTER] JOINs combine all the records from the right table and only the matching records from left table. OUTER keyword is optional.

FULL [OUTER] JOINFULL [OUTER] JOINs combine all rows from both tables regardless of match. OUTER keyword is optional.

CROSS JOINCROSS JOINs provide a Cartesian product between two tables. A Cartesian product contains all the rows from all the tables combined.

Dynamic vs. Compiled StatementsDynamic SQL StatementsConstructed at runtime with variable dataExecution plan is determined on 1stexecutionAny adhoc query is dynamic to the optimizerCompiled SQL StatementsConstructed at design timeExecution plan is known before executionStored Procedures are compiled

Execution PlansWhat is an execution plan?Query optimizer’s attempt to calculate the most efficient way to implement a query.Calculates the cost in terms of CPU, I/O, & speed.Where are they stored?Generating an execution plan is expensive, so they are stored for reuse in memory (plan cache).Are purged from memory using an aging formula that considers it’s cost and use

IndexesWhat are indexes?Catalog of locations and order of records in tableWhy use them?Speeds up queries; tables are just heaps of data without themTypes:Clustered NonClusteredCompositeUniqueCovering

Index storageAn index is a set of pages (index nodes) that are organized in a B-tree structure.Root LevelIntermediateLevelsLeaf Level

Clustered – stores the actual data rows at the leaf level of the index; physically sorted table; only 1 per tableNonClustered – leaf nodes contain only the values from the indexed columns and row locators to the actual data rows, not the actual data rows themselves; 249 per tableComposite – contains more than one column up to 16; can be clustered or nonclustered; max of 900 bytesUnique – ensures each value in the indexed column is unique. If composite, then the uniqueness is enforced across the columns as a whole. Defining a PK or unique constraint automatically creates a Unique indexCovering – includes all the columns that are needed to process a query; an extension of nonclustered functionality; adds non-key columns to the leaf level; not included when calculating number of index key columns or index key size.

If a table’s data changes frequently, keep indexes few, simple, & narrow.For tables with a lot of data and infrequent changes, use as many indexes as needed for performance.Create nonclustered indexes on columns used frequently in predicates and join conditions.Index columns with exact match queries.Don’t index small tables, a Table scan is quickerTry to keep predicate order the same as index orderPeriodically check DMVs for usage and for unused or missing indexes (sys.dm_db_index_usage_stats & sys.dm_db_missing_index_*)

Performance IssuesPossible causesBlockingCPU Bottlenecks Memory Bottlenecks I/O Bottlenecks Tools to IdentifyPerformance Monitor (PerfMon)SQL Server Profiler DBCC commandsDMVs

BlockingBlocking is primarily waits for logical locks, which occur when a request to acquire a non-compatible lock on an already-locked resource is made.Identifying:DMVs: sys.dm_os_wait*, sys.dm_tran_locksProfiler: Deadlock graph & Blocked process report

CPU BottlenecksCan be caused by insufficient hardware, poor query tuning, or excessive query compilation.Identifying:PerfMon – “%Processor Time” > 80%, ratio of “SQL Recompilations / sec” to “Batch Requests / sec” be lowProfiler – watch SP:Recompile & SQL:StmtRecompile classesDMVs – sys.dm_exec_query_stats & sys.dm_exec_query_optimizer_info

Memory BottlenecksLow memory conditions, or memory pressureUse of AWE & VAS, actual physical memory, other applicationsIdentifying:Task ManagerPerformance Monitor – “Memory: Available”, “Process: Working Set”, “Paging File:*”DMVs – sys.dm_os_memory_*DBCC MEMORYSTATUS

I/O BottlenecksCheck memory first as it can cause I/OCheck execution plans for high I/OIdentifying:PerfMon – Avg Disk Queue, Avg Disk Sec/Read, Avg Disk Sec/Write, %Disk Time, Avg Disc Reads/Sec, Avg Disk Writes/SecDMVs – sys.dm_io_* & sys.dm_os_wait_stats where wait_type like 'PAGEIOLATCH%'

Scaling it all upSingle database design isn’t appropriate hereDesigns have to incorporate multiple databases over multiple servers with different characteristicsTransactional & Analytical needs are differentIndexing strategies are differentExecution plans should be scrutinizedPartitioning becomes pertinent as current and archive data coexist

Personal toolbox, templates, & linksWatch my website and blog, I’ll post my toolbox of scripts, templates I use for object maintenance, and all the links I keep handy for referencing SQL topics.http://adamhutson.com

SQL Server 2008 Development for Programmers

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SQL Server 2008 Development for Programmers