SQL Server recovery and bulk recovery mode confusions

bulkrecoveryrecoverymodelsql-server

I have 2 confusions about SQL Server recovery and bulk recovery mode.

whether recovery process itself will generate transaction log (here what I mean the logs are the logs generated by recovery process — if any, and not generated by normal database DML/DDL operations)? Why?
in the bulk recovery mode, whether the understanding of A or B is correct (if neither is corect, please help to correct me, here are my 2 different understandings which causes me confused)

A. the normal DML/DLL bulk operation on product database (not the recovery operation) will generate minimal amount of logs, since logs are minimal, the recovery process which utilizes log, can not recover any point in the middle of bulk operations;
B. the normal DML/DLL bulk operation on product database will still generate normal large amount of logs (the same as non-bulk log recovery mode), but recovery process will treat bulk operation in transaction log as a unit to recover, which generates minimal logs for recovery process itself;

regards,
George

Best Solution

Please read the following two articles:

http://technet.microsoft.com/en-us/magazine/2009.02.logging.aspx

http://www.simple-talk.com/sql/backup-and-recovery/simple-talk-sql-server-backup-crib-sheet/

A Recovery Process does NOT create Logs. Logs are what are required in order to perform a point in time recovery process (along with a full database backup, and possibly differential backups).

A database with 'bulk-logged' recovery will function much like a 'full' one except that only the effect of bulk operations are recorded in the backups, rather than the transactions involved. These bulk operations include BCP, certain Data Transformation Services (DTS) operations, image and text manipulations, and SELECT INTO. By using a 'bulk-logged' recovery model, the bulk operations are unlogged and therefore much quicker. Point-in-time recovery is not possible if one of these bulk operations have taken place because if a log backup covers any bulk operations, the log backup contains both log records and the data pages that were changed by bulk operations, and this applies to all changes up to the point that the log was backed up.

Syntax:

ALTER TABLE {TABLENAME} 
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL} 
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
WITH VALUES

Example:

ALTER TABLE SomeTable
        ADD SomeCol Bit NULL --Or NOT NULL.
 CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
    DEFAULT (0)--Optional Default-Constraint.
WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.

Notes:

Optional Constraint Name:
If you leave out CONSTRAINT D_SomeTable_SomeCol then SQL Server will autogenerate
a Default-Contraint with a funny Name like: DF__SomeTa__SomeC__4FB7FEF6

Optional With-Values Statement:
The WITH VALUES is only needed when your Column is Nullable
and you want the Default Value used for Existing Records.
If your Column is NOT NULL, then it will automatically use the Default Value
for all Existing Records, whether you specify WITH VALUES or not.

How Inserts work with a Default-Constraint:
If you insert a Record into SomeTable and do not Specify SomeCol's value, then it will Default to 0.
If you insert a Record and Specify SomeCol's value as NULL (and your column allows nulls),
then the Default-Constraint will not be used and NULL will be inserted as the Value.

Notes were based on everyone's great feedback below.
Special Thanks to:
@Yatrix, @WalterStabosz, @YahooSerious, and @StackMan for their Comments.

Sql – How to return only the Date from a SQL Server DateTime datatype

SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, @your_date))

for example

SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE()))

gives me

2008-09-22 00:00:00.000

Pros:

No varchar<->datetime conversions required
No need to think about locale

Best Solution

Related Solutions

Sql – Add a column with a default value to an existing table in SQL Server

Syntax:

Example:

Notes:

Sql – How to return only the Date from a SQL Server DateTime datatype

Related Question