On the newsgropes recently I have encountered some posters who are perplexed by the results of their full-text searches.

The first poster was puzzled as to why searches on f.b.i. would not find F.B.I. in his content.  SQL FTS and Microsoft Search products index uppercased tokens with periods in them differently than other lower or upper cased tokens. During indexing most language word breakers will index upper cased tokens with periods in them as the token, and then the token with all the periods stripped out. So F.B.I. is indexed as F.B.I. and FBI. All tokens are stored upper cased in the index with the exception of path names (for cosmetic reasons - e.g. in Indexing services a path like c:\TeMp is stored as c:\temp as lowercase was considered to look better than uppercase).

There is no length cut off as far as I am aware. For example, C.R.E.E.P. (Committee to Re-Elect the President - the unfortunately and what we can only hope was unintentional acronym for President Richard Nixon's second election campaign) is indexed as CREEP and C.R.E.E.P. I've tried up to 10 letter combinations.

Here is an example:

Create table testAcronymTable(pk int not null identity constraint testAcronymTablePK primary key, charcol char(20))

GO

insert into  testAcronymTable(charcol) values('F.B.I.')

insert into  testAcronymTable(charcol) values('f.b.i.')

insert into  testAcronymTable(charcol) values('fbi')

insert into  testAcronymTable(charcol) values('FBI') 

insert into  testAcronymTable(charcol) values('F B I') 

insert into  testAcronymTable(charcol) values('f b i') 

GO

create fulltext catalog testacronymcatalog

GO
--indexing using the neutral word breaker
create fulltext index on testAcronymTable(charcol language 0) key index testAcronymTablePK on testAcronymCatalog
GO
--returns f.b.i., F.B.I., F B I and f b i  - expected, SQL FTS
--throws away the .'s
--you get the same results if f, b, and i are removed from the noise list
drop fulltext index on testAcronymTable
GO
--indexing using the American English Word breaker word breaker
create fulltext index on testAcronymTable(charcol language 1033) key index testAcronymTablePK on testAcronymCatalog
GO
select * from  testAcronymTable where contains(*,'fbi')
GO
--returns fbi F.B.I, and FBI - fbi, and FBI are expected, unexpected is
--F.B.I, F.B.I is indexed as F.B.I. and FBI.
select * from  testAcronymTable where contains(*,'FBI')
GO
--returns fbi F.B.I, and FBI - fbi, and FBI are expected, unexpected is
--F.B.I, F.B.I is indexed as F.B.I. and FBI.
select * from  testAcronymTable where contains(*,'F.B.I.')
GO
--returns fbi F.B.I, and FBI - F.B.I is expected, unexpected is
--FBI and fbi, F.B.I is indexed as F.B.I. and FBI.
select * from  testAcronymTable where contains(*,'f.b.i.')
GO
--returns f.b.i., F B I, and f b i -if your noise word list does not contain
--f, b, and i
--returns nothing -if your noise word list does contain
--f, b, and i

Note that this works for most languages but does NOT work for the neutral, Chinese (both types),  Japanese, and Thai word breakers. They will index F.B.I. as F, B, and I - in other words as three separate letters. Korean will index F.B.I. as F.B.I

The next post covers some of the unusual behaviors while searching on C#, C+, C++, and F#, etc

 

There seems to be some confusion out there in the internet about how to implement transaction marks. Or perhaps I was merely very confused about how to implement them.

 

Transaction marks allow you to restore two or more database to a consistent point in time. For example if you have two database and your app writes to both databases, how do you restore them to a consistent point in time without kicking all your users off the databases? This is complicated by many things, for example backup speed.

I googled looking for a working example but could not find one, so here is a script I wrote to demonstrate it.

 

create database MarkedTransaction
GO
create database MarkedTransaction1
GO
use MarkedTransaction
go
create table test1(pk int)
GO
use MarkedTransaction1
GO
create table test1(pk int)
GO
backup database MarkedTransaction to disk='c:\MarkedTransaction.bak' with init
GO
backup database MarkedTransaction1 to disk='c:\MarkedTransaction1.bak'with init
GO
begin transaction
insert into MarkedTransaction.dbo.test1(pk) values(1)
insert into MarkedTransaction1.dbo.test1(pk) values(1)
commit tran
GO
begin transaction mark6 with mark 'marked transaction'
insert into MarkedTransaction.dbo.test1(pk) values(2)
insert into MarkedTransaction1.dbo.test1(pk) values(2)
commit transaction mark6
GO
begin transaction mark7 with mark 'marked transaction - 1'
insert into MarkedTransaction.dbo.test1(pk) values(3)
insert into MarkedTransaction1.dbo.test1(pk) values(3)
commit tran mark7
GO
backup log MarkedTransaction to disk='c:\MarkedTransactionlog.bak' with init
backup log MarkedTransaction1 to disk='c:\MarkedTransactionlog1.bak' with init
GO

use master
GO
--backing up the tail
backup log MarkedTransaction to disk='c:\MarkedTransactionlogTail.bak' with init, norecovery
backup log MarkedTransaction1 to disk='c:\MarkedTransactionlog1Tail.bak' with init, norecovery
GO
--restoring the database
restore database markedtransaction from disk='c:\markedtransaction.bak' with norecovery
restore database markedtransaction1 from disk='c:\markedtransaction1.bak' with norecovery
GO
--restoring the log
RESTORE LOG MarkedTransaction FROM 
DISK = 'c:\MarkedTransactionlog.bak'
WITH  STOPATMARK = 'mark6', recovery
GO

RESTORE LOG MarkedTransaction1 FROM 
DISK = 'c:\MarkedTransactionlog1.bak'
WITH  STOPATMARK = 'mark6', recovery
GO

select * from MarkedTransaction.dbo.test1
select * from MarkedTransaction1.dbo.test1
--both 1, 2 are there, 3 is not
--repeating,  but this time we will stop before
backup database MarkedTransaction to disk='c:\MarkedTransaction.bak' with init
GO
backup database MarkedTransaction1 to disk='c:\MarkedTransaction1.bak'with init
GO
begin transaction
insert into MarkedTransaction.dbo.test1(pk) values(6)
insert into MarkedTransaction1.dbo.test1(pk) values(6)
commit transaction
GO
begin transaction mark8 with mark 'marked transaction -2'
insert into MarkedTransaction.dbo.test1(pk) values(7)
insert into MarkedTransaction1.dbo.test1(pk) values(7)
commit transaction mark8
GO
begin transaction
insert into MarkedTransaction.dbo.test1(pk) values(8)
insert into MarkedTransaction1.dbo.test1(pk) values(8)
commit transaction
GO
backup log MarkedTransaction to disk='c:\MarkedTransactionlog.bak' with init
backup log MarkedTransaction1 to disk='c:\MarkedTransactionlog1.bak' with init
GO

use master
GO
backup log MarkedTransaction to disk='c:\MarkedTransactionlogTail.bak' with init, norecovery
backup log MarkedTransaction1 to disk='c:\MarkedTransactionlog1Tail.bak' with init, norecovery
GO
RESTORE Database MarkedTransaction  from disk='c:\markedtransaction.bak' with norecovery
RESTORE Database MarkedTransaction1  from disk='c:\markedtransaction1.bak' with norecovery
GO
RESTORE LOG MarkedTransaction FROM 
DISK = N'c:\MarkedTransactionlog.bak'
WITH  STOPBEFOREMARK = N'mark8' , recovery
GO
RESTORE LOG MarkedTransaction1 FROM 
DISK = N'c:\MarkedTransactionlog1.bak'
WITH  STOPBEFOREMARK = N'mark8' , recovery
GO
select * from MarkedTransaction.dbo.test1
select * from MarkedTransaction1.dbo.test1
--both 1, 2, and 6 are there, 7 is not