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Introduction to Full-Text Searching in SQL Server 2012 Adolfo J. Socorro, Ph.D. IT Impact, Inc. [email protected] Outline What can we do with FTS? How to install FTS FTS components Creating FTS indexes How to query with FTS FILESTREAM and FileTable FTS Basics FTS allows searching against character-based data char ntext varchar image nchar xml nvarchar varbinary text varbinary(max) Search Functionality Specific words or phrases • “hotel” => “hotel” Prefixes • “fan” => “fantastic”, “fantasy” • “local store” => “locally stored” Inflectional forms • “minimized” => “minimizing”, “minimise” Search Functionality Proximity • “search,query” => “query to perform search” Synonyms • “folder” => “directory” Weighted Values A First Look Let’s run some simple examples to get a feel for FTS! LIKE vs FTS LIKE works on character patterns only Cannot use the LIKE predicate to query formatted binary data FTS is much faster against large amounts of unstructured text data Supported SQL Server Editions Enterprise Business Intelligence Standard Web Express with Advanced Services Available since at least SQL Server 2000 FTS Components Word Breaker Thesaurus Stemmer Stoplists Filters Property Lists Language Support 50+ languages Language-specific components Word breakers and stemmers Stoplists Thesaurus files How to Install Default FTS Language FTS Indexes One index per table or indexed view Must have a unique, single-column, nonnullable index on the table Grouped within the same database into one or more full-text catalogs (“containers”) Full-Text Catalogs A logical construct A way to manage FT indexes together Index Population Population: indexes the addition of data to full-text Automatic Manual • On Request • Scheduled Steps to Setup an Index on a Table Create Full-Text Catalog For Each Column to Index • Indicate language • Indicate document type * Choose Change-Tracking Mechanism Full-Text Index Wizard Example: Create Catalog and Index CONTAINS Precise or prefix matches to single words and phrases Proximity matches Logical operations between conditions: AND, OR, AND NOT Optional use of inflectional forms and thesaurus FREETEXT Matching the meaning, but not the exact wording, of specified words or phrases Always uses inflectional forms and thesaurus CONTAINSTABLE AND FREETEXTTABLE Return a relevance ranking value (RANK) and full-text key (KEY) for each row The actual RANK values are unimportant and typically differ each time the query is run ISABOUT/WEIGHT influence the ranking in CONTAINSTABLE Example: Queries Stoplists A mechanism to discard commonly occurring strings that do not help the search a is the by and … Thesaurus Nicknames: Robert/Bob Common misspellings: calendar/calender Homophones: Geoff/Jeff Technical terms: proc/procedure Very powerful if you log searches and learn what users are commonly searching for Thesaurus One file per language Expansions Replacements “bike” in addition to “bicycle” “calendar” instead of “calender” Filters Extract textual information from the document (removing the formatting) Send the text to the word-breaker component for the language associated with the column Need to manually install Office 2010 and PDF filters Example: FTS Components Where to Store Large Objects? Database File System Why Store in the Database? Integrating unstructured data into the relational database provides significant benefits: Integrated storage and data management capabilities (e.g., backup) Ease of administration and policy management Full-text search FILESTREAM A database/file system hybrid FILESTREAM is an attribute that can be assigned to a varbinary(max) column Allows Not storing BLOB data in the file system restricted to the 2 GB limit SQL Server imposes on BLOBs FILESTREAM SQL Server buffer pool is not used Isolation semantics are governed by Database Engine transaction isolation levels Steps to FILESTREAM Enable at OS level Configure at instance level Create a filegroup Add a file to the filegroup • Indicate root folder OS-level Configuration of FILESTREAM Instance-level Configuration of FILESTREAM Example: FILESTREAM FILESTREAM All data access must be transactional Must Do use specific APIs for file I/O not edit the files directly! When to Use FILESTREAM Objects that are being stored are, on average, larger than 1 MB Store smaller objects in the database Fast You read access is important are using a middle tier for application logic FileTables A special, fixed-schema kind of table Builds on top of existing FILESTREAM capabilities Store files and documents in in the database, but access them from Windows applications as if they were stored in the file system (WIN32 API) FileTables Hierarchical Includes namespace file system properties as columns Preserves full file names Non-transactional access through the FS FileTables Calls to create or change a file or directory through the Windows share are intercepted by a SQL Server component and reflected in the corresponding relational data in the FileTable Example: FTS over FileTables FileTables vs FILESTREAM File and directory hierarchy maintained in the database Windows application compatibility Relational Both access to file attributes are available in all editions Wrap Up Advanced searching on character-based data, including documents FTS setup, components, and queries FILESTREAM FileTables Other Topics Document-property Semantic search search Optimizations Query plans and execution traces References Posts http://www.sqlskills.com/blogs/bobb/ Blog: SQL Server FTS Team Blog http://blogs.msdn.com/b/sqlfts SQL and presentations by Bob Beauchemin Server 2012 Books Online http://msdn.microsoft.com/enus/library/cc645577(SQL.110).aspx Filter Packs Adobe http://www.adobe.com/support/downloads/thankyo u.jsp?ftpID=4025&fileID=3941 Office PDF Filter 2010 Filters http://www.microsoft.com/enus/download/details.aspx?id=17062