Microsoft full text indexing

For files with text, their contents are indexed to allow you to search for words within the files. Apps you install may also add their own information to the index to speed up searching. For example, Outlook adds all emails synced to your machine to the index by default and uses the index for searching within the app. Many of the built-in apps on your PC use the index in some way. File Explorer, Photos, and Groove all use it to access and track changes to your files.

Microsoft Edge uses it to provide browser history results in the address bar. Outlook uses it to search your email. Cortana uses it to provide faster search results from across your PC.

Many apps in the Microsoft Store also depend on the index to provide up-to-date search results for your files and other content. Disabling indexing will result in these apps either running slower or not working at all, depending on how heavily they rely on it. Your Windows 10 PC is constantly tracking changes to files and updating the index with the latest information. To do this, it opens recently changed files, looks at the changes, and stores the new information in the index.

All data gathered from indexing is stored locally on your PC. None of it is sent to any other computer or to Microsoft. However, apps you install on your PC may be able to read the data in the index, so be careful with what you install and make sure you trust the source.

A rule of thumb is that the index will be less than 10 percent of the size of the indexed files. For example, if you have MB of text files, the index for those files will be less than 10 MB. In both cases, the index size will increase dramatically in proportion to the size of the files.

Stoplist objects. Stoplist objects contain a list of common words that are not useful for the search. SQL Server query processor. The query processor compiles and executes SQL queries. If a SQL query includes a full-text search query, the query is sent to the Full-Text Engine, both during compilation and during execution.

The query result is matched against the full-text index. Full-Text Engine. The Full-Text Engine compiles and executes full-text queries. As part of query execution, the Full-Text Engine might receive input from the thesaurus and stoplist. Integrating the Full-Text Engine into the Database Engine improved full-text manageability, optimization of mixed query, and overall performance.

Index writer indexer. The index writer builds the structure that is used to store the indexed tokens. Filter daemon manager. The filter daemon manager is responsible for monitoring the status of the Full-Text Engine filter daemon host.

The filter daemon host is a process that is started by the Full-Text Engine. It runs the following full-text search components, which are responsible for accessing, filtering, and word breaking data from tables, as well as for word breaking and stemming the query input. Protocol handler. This component pulls the data from memory for further processing and accesses data from a user table in a specified database.

One of its responsibilities is to gather data from the columns being full-text indexed and pass it to the filter daemon host, which will apply filtering and word breaker as required.

Some data types require filtering before the data in a document can be full-text indexed, including data in varbinary , varbinary max , image , or xml columns. The filter used for a given document depends on its document type. For example, different filters are used for Microsoft Word.

Then the filter extracts chunks of text from the document, removing embedded formatting and retaining the text and, potentially, information about the position of the text. The result is a stream of textual information. For more information, see Configure and Manage Filters for Search. Word breakers and stemmers. A word breaker is a language-specific component that finds word boundaries based on the lexical rules of a given language word breaking.

Each word breaker is associated with a language-specific stemmer component that conjugates verbs and performs inflectional expansions. At indexing time, the filter daemon host uses a word breaker and stemmer to perform linguistic analysis on the textual data from a given table column.

The language that is associated with a table column in the full-text index determines which word breaker and stemmer are used for indexing the column. SQL Server However you can switch to the previous version of these components if you want to retain the previous behavior.

Full-text search is powered by the Full-Text Engine. The Full-Text Engine has two roles: indexing support and querying support. When a full-text population also known as a crawl is initiated, the Full-Text Engine pushes large batches of data into memory and notifies the filter daemon host. The host filters and word breaks the data and converts the converted data into inverted word lists.

The full-text search then pulls the converted data from the word lists, processes the data to remove stopwords, and persists the word lists for a batch into one or more inverted indexes. When indexing data stored in a varbinary max or image column, the filter, which implements the IFilter interface, extracts text based on the specified file format for that data for example, Microsoft Word.

In some cases, the filter components require the varbinary max , or image data to be written out to the filterdata folder, instead of being pushed into memory.

As part of processing, the gathered text data is passed through a word breaker to separate the text into individual tokens, or keywords. The language used for tokenization is specified at the column level, or can be identified within varbinary max , image , or xml data by the filter component. Additional processing may be performed to remove stopwords, and to normalize tokens before they are stored in the full-text index or an index fragment.

When a population has completed, a final merge process is triggered that merges the index fragments together into one master full-text index. This results in improved query performance since only the master index needs to be queried rather than a number of index fragments, and better scoring statistics may be used for relevance ranking. The query processor passes the full-text portions of a query to the Full-Text Engine for processing.

The Full-Text Engine performs word breaking and, optionally, thesaurus expansions, stemming, and stopword noise-word processing. Then the full-text portions of the query are represented in the form of SQL operators, primarily as streaming table-valued functions STVFs. During query execution, these STVFs access the inverted index to retrieve the correct results. The results are either returned to the client at this point, or they are further processed before being returned to the client.

The information in full-text indexes is used by the Full-Text Engine to compile full-text queries that can quickly search a table for particular words or combinations of words. A full-text index stores information about significant words and their location within one or more columns of a database table.

A full-text index is a special type of token-based functional index that is built and maintained by the Full-Text Engine for SQL Server. Select this radio button to kick off a full population at the successful completion of this wizard.

This will consist of creating the full-text index structure in the catalog and populating it with full-text indexed data. Select a catalog: Select a full-text catalog from the list. The default catalog for the database will be the selected item by default in the list. If no catalogs are available, the list will be disabled, and the Create a new catalog checkbox will be checked and disabled. Set as default catalog Select to make the catalog the default for this database. Accent sensitivity Specify whether the new catalog will be accent-sensitive or accent-insensitive.

If the database is accent-sensitive, Sensitive is selected by default. Select index filegroup Specify the filegroup on which to create the full-text index. Select full-text stoplist Specify a stoplist to use for the full-text index, or disable stoplist use. Stopwords are managed in databases using objects called stoplists.

A stoplist is a list of stopwords that, when associated with a full-text index, is applied to full-text queries on that index. Optionally, SQL Server only, define the population schedule. Indexing operations will begin immediately unless they have been scheduled for future execution. Schedules will be created immediately, although they will not run until their scheduled time. Stop Interrupts the current operation and prevents subsequent full-text operations from being performed by the wizard during this session.

Report When all of the operations have finished executing, click this button to access a report on the operations performed. You can view the report, print it to a file, copy it to the clipboard, or e-mail the report.

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