Setting Up a Full-Text Index (part 1) - Using T-SQL Commands to Build Full-Text Indexes and Catalogs

• Using T-SQL commands

• Using the Full-Text Wizard

Using T-SQL Commands to Build Full-Text Indexes and Catalogs

In SQL 2008 full-text catalogs are “virtual.” They are just containers for full-text catalog properties like accent sensitivity or catalog rebuild or population statements. They live inside the database in SQL 2008, unlike SQL 2000 and 2005, where the catalogs and full-text indexes resided in the filesystem.

To build your full-text catalogs and indexes, you need to use the CREATE FULLTEXT commands.

There are three commands for full-text index creation and maintenance:

• CREATE FULLTEXT CATALOG

• CREATE FULLTEXT INDEX

• ALTER FULLTEXT INDEX

Let’s look at how they work.

CREATE FULLTEXT CATALOG

To create a full-text catalog in its simplest form, you enter this command:

USE AdventureWorks;
Create fulltext catalog  MyCatalog

In this command, MyCatalog is the name of the catalog. The CREATE FULLTEXT CATALOG statement has several switches:

• ON FILEGROUP

• IN PATH

• WITH ACCENT_SENSITIVITY

• AS DEFAULT

• AUTHORIZATION

We next cover each of these parameters.

ON FILEGROUP

The ON FILEGROUP command is for backward compatibility only.

IN PATH

The IN PATH command is for backwards compatibility only.

WITH ACCENT_SENSITIVITY

The WITH ACCENT_SENSITIVITY option allows you to create a catalog that is sensitive (Accent_Sensitivity ON) to accents (the default) or insensitive to accents. With Accent_Sensitivity OFF, a search on café would match with café and cafe. Likewise, a search on cafe would match with cafe and café. With Accent_Sensitivity ON, a search on café would match only with café and not cafe. Likewise, a search on cafe would match only with cafe and not café.

The following is the typical syntax for using the option:

USE AdventureWorks;
CREATE FULLTEXT CATALOG MyCatalog ON FILEGROUP MyFileGroup
    WITH ACCENT_SENSITIVITY = OFF

AS DEFAULT

The AS DEFAULT option allows you to create a default full-text catalog for every full-text index in a database. This option is convenient because you don’t have to specify the full-text catalog for your full-text indexes. Ideally, each large table will have its own full-text catalog, so although it saves some time typing the commands, this option is not the best one to use all the time. For example, when you create a full-text index, at a minimum, you need to use the following:

Use AdventureWorks;
CREATE FULLTEXT INDEX ON person.Contact(Firstname)
     KEY INDEX pk_Contact_ContactID ON MyCatalog

With a default catalog for your database, all you have to type is this:

Use AdventureWorks;
CREATE FULLTEXT INDEX ON person.Contact(Firstname) KEY INDEX pk_Contact_ContactID


					  

Msg 9967, Level 16, State 1, Line 2
A default full-text catalog does not exist in database 'AdventureWorks'
 or user does not have permission to perform this action.

Here is the syntax to create a default catalog: Create FullText Catalog AdventureWorksFT as Default

AUTHORIZATION

The AUTHORIZATION option allows a user or a role to own and consequently manage a full-text catalog. The following is the typical syntax for using this option:

Use AdventureWorks;
CREATE FULLTEXT CATALOG MyCatalog WITH ACCENT_SENSITIVITY =OFF Authorization [dbo]


					  

CREATE FULLTEXT INDEX

You use the CREATE FULLTEXT INDEX command to create full-text indexes. Your searches query full-text indexes to return results.

The CREATE FULLTEXT INDEX command has several parameters:

• COLUMN NAME

• TYPE COLUMN

• LANGUAGE

• ON FULL-TEXT CATALOG

• KEY INDEX

• POPULATION TYPE

We next cover each of these parameters.

COLUMN NAME

The COLUMN NAME parameter is the char, varchar, nchar, nvarchar, text, or xml column that you are full-text indexing. A minimal CREATE FULLTEXT INDEX statement would look like this:

Use AdventureWorks;
CREATE FULLTEXT INDEX ON Person.Contact(Firstname) KEY INDEX pk_Contact_ContactID


					  

A default full-text catalog does not exist in database 'AdventureWorks'
    or user does not have permission to perform this action.

You specify a full-text catalog by using the following command:

Use AdventureWorks;
CREATE FULLTEXT INDEX ON Person.Contact(Firstname, Lastname)
     KEY INDEX pk_Contact_ContactID ON MyCatalog

In this command, MyCatalog is the name of the full-text catalog. Note that the second example creates a full-text index on two columns.

TYPE COLUMN

You can index columns of the char, varchar, nchar, nvarchar, text, ntext, and xml data types. You can also index columns of the image and varbinary(max) data types if you have an ancillary column, which tells what the content is in that column. The reason for this is the Indexer needs to interpret the binary data in the image and varbinary(max) columns and will need to load an IFilter, which corresponds to the binary data stored in these columns. The Indexer will load the IFilter, which corresponds to the extension stored in this ancillary column. For example, if you store a PDF in the image or varbinary(max) column, the ancillary column would have to have the value PDF or .PDF (not case sensitive) so the PDF IFilter would be launched.

There is a relevant example in the AdventureWorks database. Consider the Production.Document table. If you want to search Word documents stored in this table, a LIKE clause search would not work because the Word documents are in binary format. Full-text indexing on the Document column similarly wouldn’t work because the IFilter would not be able to interpret the binary stream. So you need to add a column that contains the extension the document in this row would have if it were stored in the filesystem; in this case, it’s a Word document, so the extension would be .doc. This column is called a document type column. In the Production.Document table, this column is the FileExtension column. When you index binary large objects (BLOBs), there are special considerations, as discussed in the next section.