Definition of Rollback and Roll forward?

Rollback: The Rollback transaction is a transaction which rolls back the transaction to the beginning of the transaction. The transaction can be rolled back completely by specifying the transaction name in the Rollback statement or to cancel any changes to a database during current transaction. It is permissible to use before Commit transaction.

Roll forward: Recovering a database by applying different transactions that recorded in the database log files. It is nothing but re-doing the changes made by a transaction i.e. after the committed transaction and to over write the changed value again to ensure consistency.

Comparison of relational database management systems

General information:

DB	Maintainer	First public release date	Latest Stable version	Latest release date	Software license
DB2	IBM	1983	10.1	2012-04-30	Proprietary
Microsoft SQL Server	Microsoft	1989	2012 (v11)		Proprietary
MySQL	Sun Microsystems (now Oracle Corporation)	1995-11	5.5.17	2011-10-21	GPL or Proprietary
Oracle	Oracle Corporation	1979-11	11g Release 2	2009-09	Proprietary

 
Operating system support:

DB	Windows	Mac OS X	Linux	BSD	UNIX	Amiga OS	Symbian	z/OS1	iOS	Android
DB2	Yes	Yes (Express C)	Yes	No	Yes	No	No	Yes	Yes	No
Microsoft SQL Server	Yes	No	No	No	No	No	No	No	No	No
MySQL	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	?	No
Oracle	Yes	Yes	Yes	No	Yes	No	No	Yes	No	No

 Fundamental features:

DB	ACID	Referential integrity	Transactions	Unicode	Interface
DB2	Yes	Yes	Yes	Yes	GUI & SQL
Microsoft SQL Server	Yes	Yes	Yes	Yes	GUI & SQL
MySQL	Yes	Partial	Yes except for DDL	Yes	SQL
Oracle	Yes	Yes	Yes except for DDL	Yes	API & GUI & SQL

Limits:

DB	Max DB  size	Max table size	Max row size	Max columns per row	Max Blob/Clob size	Max CHAR size	Max NUMBER size	Min DATE value	Max DATE value	Max column name size
DB2	512 TiB	512 TB	32 677 B	1012	2 GB	32 KiB	64 bits	0001	9999	128
Microsoft SQL Server	524,272 TB (32 767 files * 16 TB max file size)	524,272 TB	8060 bytes (Unlimited)	30000	2 GB	2 GB	126 bits	0001	9999	128
MySQL	Unlimited	MyISAM storage limits: 256 TB; Innodb storage limits: 64 TB	64 kB	4096	4 GB (longtext, longblob)	64 kB (text)	64 bits	1000	9999	64
Oracle	Unlimited (4 GB * block size per tablespace)	4 GB * block size (with BIGFILE tablespace)	8 kB	1000	Unlimited	4000 B	126 bits	-4712	9999	30

 Tables and views:
Information about what tables and views (other than basic ones) are supported natively.  

DB	Temporary table	Materialized view
DB2	Yes	Yes
Microsoft SQL Server	Yes	Yes
MySQL	Yes	No
Oracle	Yes	Yes

Indexes:
Information about what indexes (other than basic B-/B+ tree indexes) are supported natively.

DB	R-/R+ tree	Hash	Expression	Partial	Reverse	Bitmap	GiST	GIN	Full-text	Spatial	FOT
DB2	No	?	Yes	No	Yes	Yes	No	No	Yes	?
Microsoft SQL Server	?	Non/Cluster & fill factor	Yes	Yes	No	No	No	No	Yes	Yes
MySQL	MyISAM tables only	MEMORY, Cluster (NDB), InnoDB, tables only	No	No	No	No	No	No	MyISAM tables only	MyISAM tables only	?
Oracle	Yes	Cluster Tables	Yes	Yes	Yes	Yes	No	No	Yes	Yes

  Database capabilities:

DB	Union	Intersect	Except	Inner joins	Outer joins	Inner selects	Merge joins	Blobs and Clobs	Common Table Expressions	Windowing Functions	Parallel Query
DB2	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Microsoft SQL Server	Yes	Yes (2005 and beyond)	Yes (2005 and beyond)	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
MySQL	Yes	No	No	Yes	Yes	Yes	No	Yes	No	No	No
Oracle	Yes	Yes	Yes, via MINUS	Yes	Yes	Yes	Yes	Yes	Yes 1	Yes	Yes

Data types:

DB	Type system	Integer	Floating point	Decimal	String	Binary	Date/Time	Boolean	Other
DB2
Microsoft SQL Server	Static	TINYINT, SMALLINT, INT, BIGINT	FLOAT, REAL	NUMERIC, DECIMAL, SMALLMONEY, MONEY	CHAR, VARCHAR, TEXT, NCHAR, NVARCHAR, NTEXT	BINARY, VARBINARY, IMAGE, FILESTREAM	DATE, DATETIMEOFFSET, DATETIME2, SMALLDATETIME, DATETIME, TIME	BIT	CURSOR, TIMESTAMP, HIERARCHYID, UNIQUEIDENTIFIER, SQL_VARIANT, XML, TABLE
MySQL	Static	TINYINT (8-bit), SMALLINT (16-bit), MEDIUMINT (24-bit), INT (32-bit), BIGINT (64-bit)	FLOAT (32-bit), DOUBLE (aka REAL) (64-bit)	DECIMAL	CHAR, BINARY, VARCHAR, VARBINARY, TEXT, TINYTEXT, MEDIUMTEXT, LONGTEXT	TINYBLOB, BLOB, MEDIUMBLOB, LONGBLOB	DATETIME, DATE, TIMESTAMP, YEAR	BOOLEAN (aka BOOL) = synonym for TINYINT	ENUM, SET, GIS data types (Geometry, Point, Curve, LineString, Surface, Polygon, GeometryCollection, MultiPoint, MultiCurve, MultiLineString, MultiSurface, MultiPolygon)
Oracle	Static + Dynamic (through ANYDATA)	NUMBER	BINARY_FLOAT, BINARY_DOUBLE	NUMBER	CHAR, VARCHAR2, CLOB, NCLOB, NVARCHAR2, NCHAR	BLOB, RAW, LONGRAW, BFILE	DATE, TIMESTAMP (with/without TIMEZONE), INTERVAL	N/A	SPATIAL, IMAGE, AUDIO, VIDEO, DICOM, XMLType

 Other objects:
Information about what other objects are supported natively.

DB	Data Domain	Cursor	Trigger	Function	Procedure	External routine
DB2	Yes via CHECK CONSTRAINT	Yes	Yes	Yes	Yes	Yes
Microsoft SQL Server	Yes (2000 and beyond)	Yes	Yes	Yes	Yes	Yes
MySQL	No	Yes	Yes	Yes	Yes	Yes
Oracle	Yes	Yes	Yes	Yes	Yes	Yes

Partitioning:
Information about what partitioning methods are supported natively.

DB	Range	Hash	Composite (Range+Hash)	List	Expression
DB2	Yes	Yes	Yes	Yes
Microsoft SQL Server	Yes	No	No	No
MySQL	Yes	Yes	Yes	Yes
Oracle	Yes	Yes	Yes	Yes

Access control:
Information about access control functionalities (work in progress).

DB	Native network encryption	Brute-force protection	Enterprise directory compatibility	Password complexity rules	Patch access	Run unprivileged	Audit	Resource limit	Separation of duties (RBAC)	Security Certification
DB2	Yes	?	Yes (LDAP, Kerberos…)	Yes	?	Yes	Yes	Yes	Yes	Yes (EAL4+)
Microsoft SQL Server	Yes	?	Yes (Microsoft Active Directory)	Yes	Yes	Yes	Yes (From 2008)	Yes	Yes	Yes (EAL1+)
MySQL	Yes (SSL with 4.0)	No	Yes (with 5.5, but only in commercial edition)	No	Partial (no security page)	Yes	?	?	?	No
Oracle	Yes	Yes	Yes	Yes	?	Yes	Yes	Yes	Yes	Yes (EAL4+)