Re: What is a TABLESPACE?

The same is true of DB2 - if a tablespace is spread across multiple containers, each of these containers can be on a separate device, allowing for parallel I/O. You can also put indexes on high-speed devices and long fields on slow-speed devices.

"Daniel A. Morgan" wrote:

> continuing from what you wrote ...
>
> And in Oracle tablespaces almost always are used to break up tables and indexes
> and place them onto separate physical drives to improve performance. Beyond that
> my impression is that most DBAs (myself included) use a different tablespace for
> tables of different extent sizes to remove the problem of tablespace
> fragmentation. So, for example, I might have one tablespace for small tables
> where the extent size is 512K and another for tables of 5M and another for 500M.
>
> Daniel A. Morgan
>
> Blair Kenneth Adamache wrote:
>
> > A tablespace can hold one or more tables, and indexes and/or the long fields
> > (CLOBs, BLOBs, LONG VARCHARs) for a table. It maps the logical data
> > (tabular view) to the physical storage devices (files or containers on a
> > file system).
> >
> > By default, tables you create are created in the tablespace USERSPACE1. If
> > you want to have more control of where your data is placed, you have to
> > created additional table spaces.
> >
> > On DB2 for OS/390, some DBAs like to put each table in its own tablespace.
> > On DB2 on UNIX, OS/2 and Windows, the common practice is to put all related
> > tables (those with referential constraints against each other) in the same
> > tablespace.
> >
> > Combined with the CREATE BUFFERPOOL command, the CREATE TABLESPACE command
> > gives you a lot of control of your data, including:
> > - whether the maximum row width is 4K, 8K, 16K or 32K
> > - the maximum number of columns in a table
> > - whether the table data is stored on raw devices or on the file system
> > - the ability to restore a tablespace from a backup image rather than a full
> > database backup image
> > - the ability to give a table a better chance of being cached in memory by
> > assigning it to its own bufferpool
> >
> > Wyvette Banks wrote:
> >
> > > Hi,
> > >
> > > I am a novice in the Database world. What is a TABLESPACE, and when do I
> > > use it?
> > >
> > > I was creating a Table in DB2 and it gave me two default choices for a
> > > TABLESPACE name:
> > > 1. None
> > > 2. USERSPACE1
> > > What is happening if I choose None or if I choose USERSPACE1? I noticed
> > > this in Oracle as well, so image this is a DBMS thing.
> > >
> > > Gil
Received on Sat Mar 24 2001 - 11:12:35 CST