About IFilters (Search Server 2008)
Applies To: Microsoft Search Server 2008
Topic Last Modified: 2009-04-07
Note
Unless otherwise noted, the information in this article applies to both Microsoft Search Server 2008 and Microsoft Search Server 2008 Express.
The content that is contained in each file that is crawled must be stripped of formatting before it can be added to the content index. The formatting of a file depends on the application that created it. For example, a document created in Microsoft Office Word is in a different format than slides that are created in Microsoft Office PowerPoint. The Search Server 2008 indexing engine uses IFilters to remove embedded formatting from the content that is extracted from crawled items.
The following table summarizes the behavior of the indexing system depending on whether an IFilter is installed on the index server and whether the file type is listed on the Manage File Types page in Search Administration.
| IFilter installed? | File type listed on the Manage File Types page? | Result |
|---|---|---|
Yes |
Yes |
The content in the file and its properties are indexed. |
No |
Yes |
The content in the file is not indexed but its properties are indexed. |
No |
No |
Neither the content in the file nor its properties are indexed. |
IFilters and file types
Each IFilter must be associated with the kind of file that it can filter. A file’s type is identified by the three- or four-letter extension of the file name. You can view a list of file types for which Search Server has an IFilter installed on the Manage File Types page in Search Administration. If there is no IFilter for a file type that you want to crawl, the content index in Search Server can only include the file’s properties, and not the file’s content. If you want to index content that does not have an IFilter installed by default, you have to install and register an IFilter for that file type.
The following table lists the default settings on the Manage File Types page. This includes file types that are supported by an IFilter, but are not enabled, by default. Also, some file types are listed on the Manage File Types page that do not have IFilter support, by default. For information about how to update the Manage File Types page, see Specify file types to crawl (Search Server 2008).
| File name extension | Default IFilter Support | Default file type inclusion |
|---|---|---|
ascx |
Yes |
Yes |
asm |
Yes |
No |
asp |
Yes |
Yes |
aspx |
Yes |
Yes |
bat |
Yes |
No |
c |
Yes |
No |
cmd |
Yes |
No |
cpp |
Yes |
No |
css |
Yes |
No |
cxx |
Yes |
No |
def |
Yes |
No |
dic |
Yes |
No |
doc |
Yes |
Yes |
docm |
Yes |
Yes |
docx |
Yes |
Yes |
dot |
Yes |
Yes |
eml |
Yes |
Yes |
exch |
No |
Yes |
h |
Yes |
No |
hhc |
Yes |
No |
hht |
Yes |
No |
hpp |
Yes |
No |
hta |
Yes |
No |
htm |
Yes |
Yes |
html |
Yes |
Yes |
htw |
Yes |
No |
htx |
Yes |
No |
jhtml |
No |
Yes |
jsp |
No |
Yes |
lnk |
Yes |
No |
mht |
Yes |
Yes |
mhtml |
Yes |
Yes |
mpx |
Yes |
No |
msg |
Yes |
Yes |
mspx |
No |
Yes |
nsf |
No |
Yes |
odc |
Yes |
Yes |
one |
No |
No |
php |
No |
Yes |
pot |
Yes |
No |
pps |
Yes |
No |
ppt |
Yes |
Yes |
pptm |
Yes |
Yes |
pptx |
Yes |
Yes |
pub |
Yes |
Yes |
stm |
Yes |
No |
tif |
Yes |
Yes |
tiff |
No |
Yes |
trf |
Yes |
No |
txt |
Yes |
Yes |
url |
No |
Yes |
vdx |
No |
Yes |
vsd |
No |
Yes |
vss |
No |
Yes |
vst |
No |
Yes |
vsx |
No |
Yes |
vtx |
No |
Yes |
xlb |
Yes |
No |
xlc |
Yes |
No |
xls |
Yes |
Yes |
xlsm |
Yes |
Yes |
xlxs |
Yes |
Yes |
xlt |
Yes |
No |
xml |
Yes |
Yes |
Note
IFilters that enable Office SharePoint Server 2007 to index Adobe Portable Document Format (PDF) are provided by Adobe. For more information about installing and configuring these IFilters, see Icons are not displayed for Adobe PDF documents that are listed in the search results when you search your portal site in SharePoint Portal Server 2003 or in SharePoint Server 2007 (https://go.microsoft.com/fwlink/?LinkID=144596&clcid=0x409).
Microsoft Filter Pack
Microsoft provides a filter pack that contains a set of IFilters that are in addition to the IFilters that install automatically with Search Server 2008. The Microsoft Filter Pack installs and registers IFilters for the following file formats: .docx, .docm, .pptx, .pptm, .xlsx, .xlsm, .xlsb, .zip, .one, .vdx, .vsd, .vss, .vst, .vdx, .vsx, and .vtx.
For more information, see Install the Microsoft Filter Pack (Search Server 2008).
Custom filters
If you have to crawl documents that are of a file type that is not supported by an IFilter provided with Search Server or included in the Microsoft Filter Pack, you must install the appropriate IFilter on the index server. Check with the company that created the application to see whether it has an IFilter for Microsoft search products. If the application was created within your own organization, the software developers who created or maintain the application can create an IFilter for it. For more information, see Microsoft Search Server 2008 Software Development Kit (SDK) (https://go.microsoft.com/fwlink/?LinkId=141179).
After you install the IFilter, you must also register the IFilter with the operating system and associate it with the kind of file that it can process. The installation and registration steps are different for each IFilter. Read the IFilter’s documentation for more information.
See Also
Concepts
Install the Microsoft Filter Pack (Search Server 2008)
About protocol handlers (Search Server 2008)