Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated:
1
00:00:01,360 --> 00:00:03,910
In this lesson, we want
to examine the difference
2
00:00:03,910 --> 00:00:06,730
between the terms
instance and database
3
00:00:06,730 --> 00:00:09,250
as they relate to the
Oracle Database System.
4
00:00:09,250 --> 00:00:13,900
Oracle is a Relational Database
Management System, or RDBMS.
5
00:00:13,900 --> 00:00:17,650
And what makes a RDBMS
is the fact that it
6
00:00:17,650 --> 00:00:22,120
uses tables and relates the
data in the tables together
7
00:00:22,120 --> 00:00:24,070
in order to form
things like joins
8
00:00:24,070 --> 00:00:27,310
and to be able to separate
the data and yet still make
9
00:00:27,310 --> 00:00:29,790
it relatable together,
whenever you need it.
10
00:00:29,790 --> 00:00:32,500
And RDBMS is the most
common form of database
11
00:00:32,500 --> 00:00:33,760
that's out there today.
12
00:00:33,760 --> 00:00:36,130
There are many different
brands, if you will,
13
00:00:36,130 --> 00:00:42,230
of RDBMS, such as MySQL, SQL
Server from Microsoft, and DB2.
14
00:00:42,230 --> 00:00:44,620
And all of them have
some kind of difference
15
00:00:44,620 --> 00:00:46,150
in their architecture.
16
00:00:46,150 --> 00:00:49,000
The terms instance in
database mean different things
17
00:00:49,000 --> 00:00:51,040
in different RDBMSs.
18
00:00:51,040 --> 00:00:53,290
For instance, in
Microsoft SQL Server,
19
00:00:53,290 --> 00:00:58,150
the term instance refers more
to the installation itself,
20
00:00:58,150 --> 00:01:00,880
and the database refers
to a set of tables.
21
00:01:00,880 --> 00:01:04,180
This is more like a
schema would be in Oracle
22
00:01:04,180 --> 00:01:05,960
with that set of tables.
23
00:01:05,960 --> 00:01:09,220
So it's important to understand
that different RDBMSs have
24
00:01:09,220 --> 00:01:11,380
different uses of the terms.
25
00:01:11,380 --> 00:01:13,300
For our purposes,
there are three reasons
26
00:01:13,300 --> 00:01:16,290
to distinguish between an
instance and a database
27
00:01:16,290 --> 00:01:18,190
in the Oracle RDBMS.
28
00:01:18,190 --> 00:01:21,070
As we've said, in
other RDBMSs, the terms
29
00:01:21,070 --> 00:01:22,510
mean different things.
30
00:01:22,510 --> 00:01:25,330
Second of all, we can
see the relationship
31
00:01:25,330 --> 00:01:27,310
between the instance
in the database
32
00:01:27,310 --> 00:01:28,600
through their separation.
33
00:01:28,600 --> 00:01:31,670
That is to say, having
a division of labor,
34
00:01:31,670 --> 00:01:33,810
if you will, between an
instance in a database
35
00:01:33,810 --> 00:01:36,370
helps us to more
clearly identify
36
00:01:36,370 --> 00:01:38,470
what each component does.
37
00:01:38,470 --> 00:01:40,570
And the third, and
probably most important,
38
00:01:40,570 --> 00:01:43,840
is that the difference between
an instance and a database
39
00:01:43,840 --> 00:01:46,060
is underscored by
two different Oracle
40
00:01:46,060 --> 00:01:50,350
architectures-- single
instance database versus RAC.
41
00:01:50,350 --> 00:01:53,650
In a single instance database
generally the instance
42
00:01:53,650 --> 00:01:56,620
in the database are housed
together in a single system,
43
00:01:56,620 --> 00:01:59,350
and that's by far the most
common type of Oracle database
44
00:01:59,350 --> 00:02:01,270
that a DBA would find.
45
00:02:01,270 --> 00:02:03,640
However, on RAC,
there's a separation,
46
00:02:03,640 --> 00:02:06,910
a distinct separation between
an instance and a database.
47
00:02:06,910 --> 00:02:09,940
Physical machines
involved are separated.
48
00:02:09,940 --> 00:02:11,890
So let's define an instance.
49
00:02:11,890 --> 00:02:15,310
An instance is composed of the
background processes and memory
50
00:02:15,310 --> 00:02:18,470
structures in Oracle
necessary to do work.
51
00:02:18,470 --> 00:02:20,380
So background
processes are going
52
00:02:20,380 --> 00:02:25,300
to be individual processes that
are more aligned with the CPU
53
00:02:25,300 --> 00:02:28,000
as far as a resource
in the computer.
54
00:02:28,000 --> 00:02:31,450
We're going to see that each
one of these major components
55
00:02:31,450 --> 00:02:34,330
in the instance
and database maps
56
00:02:34,330 --> 00:02:36,710
to a resource in our computer.
57
00:02:36,710 --> 00:02:39,130
So every computer has
three basic resources--
58
00:02:39,130 --> 00:02:41,390
the CPU, the RAM and the disk.
59
00:02:41,390 --> 00:02:42,970
And each one of these
major components
60
00:02:42,970 --> 00:02:45,760
will map to those in
some direct fashion.
61
00:02:45,760 --> 00:02:48,250
So background
processes are processes
62
00:02:48,250 --> 00:02:51,370
that go out and do work,
they go out and do things,
63
00:02:51,370 --> 00:02:53,410
and they align with the CPU.
64
00:02:53,410 --> 00:02:55,150
The second component
of the instance
65
00:02:55,150 --> 00:02:58,370
are the memory structures--
the caches, if you will.
66
00:02:58,370 --> 00:03:00,880
And they map directly
to, of course, the RAM
67
00:03:00,880 --> 00:03:02,920
in a system, the memory itself.
68
00:03:02,920 --> 00:03:06,130
In Oracle, it's been said
that everything is a cache.
69
00:03:06,130 --> 00:03:08,440
So in Oracle, the
background processes
70
00:03:08,440 --> 00:03:12,520
tend to operate on data
within RAM or memory,
71
00:03:12,520 --> 00:03:14,620
what we would call
an Oracle cache
72
00:03:14,620 --> 00:03:18,700
rather than on the disk itself,
because RAM memory is orders
73
00:03:18,700 --> 00:03:21,700
of magnitude faster than disk.
74
00:03:21,700 --> 00:03:23,980
So those are the two
components of the instance.
75
00:03:23,980 --> 00:03:28,120
The database as we define it is
composed of one main component,
76
00:03:28,120 --> 00:03:29,620
and that are the data files.
77
00:03:29,620 --> 00:03:33,190
So these are the actual
physical data files on the disk.
78
00:03:33,190 --> 00:03:36,100
If they're in a file system,
you can go out to them
79
00:03:36,100 --> 00:03:37,180
and see them.
80
00:03:37,180 --> 00:03:39,820
If they're on Windows, you
can use your Windows Explorer
81
00:03:39,820 --> 00:03:40,900
to go out and find them.
82
00:03:40,900 --> 00:03:43,480
But they are files that
you actually see on disk,
83
00:03:43,480 --> 00:03:45,580
and each one of
the data files has
84
00:03:45,580 --> 00:03:49,400
a different job-- it stores
a different type of data.
6843
Can't find what you're looking for?
Get subtitles in any language from opensubtitles.com, and translate them here.