Does the Full-Text Filter Daemon Launcher service need to be running for Full-Text-Search queries to run successfully?

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Does the Full-Text Filter Daemon Launcher service need to be running for Full-Text-Search queries to run successfully?

Marios Philippopoulos

SSC Guru

Points: 57190
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April 8, 2011 at 2:51 pm

#235480

I don't understand the role of this service in SQL 2008 full-text search: Full-Text Filter Daemon Launcher.
Does this service need to be running for full-text-search queries to be running successfully?
A query like the one below runs fine even when the service is down:
SELECT * from Document
WHERE CONTAINS(DocCol, 'price');
What type of queries would break when the Daemon Launcher service is down?
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SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
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Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

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Craig Purnell SSCrazy Points: 2720 More actions · Answer 1

The Filter Daemon launches filter processes. Starting in SQL 2008, the Full Text engine is entirely within the SQL engine. See MSDN for more info:

http://msdn.microsoft.com/en-us/library/ms142541.aspx

Marios Philippopoulos SSC Guru Points: 57190 More actions · Answer 2

Craig Purnell (4/9/2011)
The Filter Daemon launches filter processes. Starting in SQL 2008, the Full Text engine is entirely within the SQL engine. See MSDN for more info:
http://msdn.microsoft.com/en-us/library/ms142541.aspx

Thank you, so if I understand correctly, this service needs to be running only in this case:

when processing data contained in a varbinary, varbinary(max), image, or xml data type column

(http://msdn.microsoft.com/en-us/library/ms142499.aspx)

So, if my full-text-search application does not deal with these types of columns, the filter-daemon service is not needed and can be stopped.

__________________________________________________________________________________
SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
Persisting SQL Server Index-Usage Statistics with MERGE[/url]
Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

Marios Philippopoulos SSC Guru Points: 57190 More actions · Answer 3

Marios Philippopoulos (4/9/2011)
Craig Purnell (4/9/2011)
The Filter Daemon launches filter processes. Starting in SQL 2008, the Full Text engine is entirely within the SQL engine. See MSDN for more info:
http://msdn.microsoft.com/en-us/library/ms142541.aspx
Thank you, so if I understand correctly, this service needs to be running only in this case:
when processing data contained in a varbinary, varbinary(max), image, or xml data type column
(http://msdn.microsoft.com/en-us/library/ms142499.aspx)
So, if my full-text-search application does not deal with these types of columns, the filter-daemon service is not needed and can be stopped.

Can someone please confirm if my assumption above is valid?

(ie. that the filter-daemon service is not needed if FTS is used only on VARCHAR-type columns.)

__________________________________________________________________________________
SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
Persisting SQL Server Index-Usage Statistics with MERGE[/url]
Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

Craig Purnell SSCrazy Points: 2720 More actions · Answer 4

Craig Purnell

SSCrazy

Points: 2720

April 11, 2011 at 12:02 pm

#1310005

I think that's right.

Marios Philippopoulos SSC Guru Points: 57190 More actions · Answer 5

Craig Purnell (4/11/2011)
I think that's right.

Thank you, we are developing some new FTS functionality and will test with the service down to see what happens.

__________________________________________________________________________________
SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
Persisting SQL Server Index-Usage Statistics with MERGE[/url]
Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

Marios Philippopoulos SSC Guru Points: 57190 More actions · Answer 6

Marios Philippopoulos (4/11/2011)
Craig Purnell (4/11/2011)
I think that's right.
Thank you, we are developing some new FTS functionality and will test with the service down to see what happens.

The query below actually fails, when the filter daemon service is down; now I'm confused:

select col2 from tbl1

where freetext(col1, 'abcd')

Msg 30046, Level 16, State 1, Procedure sp_fulltext_service, Line 163

SQL Server encountered error 0x80070422 while communicating with full-text filter daemon host (FDHost) process. Make sure that the FDHost process is running. To re-start the FDHost process, run the sp_fulltext_service 'restart_all_fdhosts' command or restart the SQL Server instance.

__________________________________________________________________________________
SQL Server 2016 Columnstore Index Enhancements - System Views for Disk-Based Tables[/url]
Persisting SQL Server Index-Usage Statistics with MERGE[/url]
Turbocharge Your Database Maintenance With Service Broker: Part 2[/url]

freewaresucks SSC Enthusiast Points: 197 More actions · Answer 7

Maybe this link might help it says the full text can be utilized into applications and can be used that way and the such. http://www.sql-server-performance.com/2010/full-text-search-2008/

C. Westra SSC Enthusiast Points: 156 More actions · Answer 8

The description of Full-text Search for Sql Server 2008 R2 says about the Filter Daemon Host Process:

"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."

http://technet.microsoft.com/en-us/library/ms142541(v=sql.105).aspx

It is the same for Sql Server 2008 and 2012.