Database Reference
In-Depth Information
Oracle also has a set of files that the database processes or threads read and write (and Oracle processes are the
only ones allowed to read or write these files). In a single-tenant architecture, these files hold all of our table data,
indexes, temporary space, redo logs, PL/SQL code, and so on. In a multitenant architecture, the container database
will hold all of the Oracle-related metadata, data, and code; our application data will be separately contained in
a pluggable database, which we have yet to create. The database we created earlier is a single-tenant database by
default; it does not have pluggable databases enabled. The self-contained set of files includes data files that contain
both the Oracle data, as well as the application data.
If you were to start up Oracle on a UNIX/Linux-based system and execute a ps command, you'd see that many
physical processes are running, with various names. You saw an example of that earlier when you observed the pmon ,
smon , and other processes. I cover these processes in Chapter 5, so just be aware for now that they are commonly
referred to as the Oracle background processes . They are persistent processes that make up the instance, and you'll see
them from the time you start the instance until you shut it down.
It is interesting to note that these are processes, not individual programs. There is only one Oracle binary
executable on UNIX/Linux; it has many “personalities,” depending on what it was told to do when it starts up. The same
binary executable that was run to start ora_pmon_ora12c was also used to start the process ora_ckpt_ora12c . There is
only one binary executable program, named simply oracle . It is just executed many times with different names.
On Windows, using the pstat tool (part of the Windows XP Resource Kit; search for “pstat download” using
your favorite search engine if you don't have it), we'll find only one process, oracle.exe . Again, on Windows there
is only one binary executable ( oracle.exe ). Within this process, we'll find many threads representing the Oracle
background processes.
Using pstat (or any of a number of tools, such as tasklist , which comes with many Windows versions), we can
see these processes:
C:\WINDOWS> pstat
Pstat version 0.3: memory: 523760 kb uptime: 0 1:37:54.375
PageFile: \??\C:\pagefile.sys
Current Size: 678912 kb Total Used: 228316 kb Peak Used 605488 kb
Memory: 523760K Avail: 224492K TotalWs: 276932K InRam Kernel: 872K P:20540K
Commit: 418468K/ 372204K Limit:1169048K Peak:1187396K Pool N:10620K P:24588K
User Time Kernel Time Ws Faults Commit Pri Hnd Thd Pid Name
56860 2348193 File Cache
0:00:00.000 1:02:23.109 28 0 0 0 0 1 0 Idle Process
0:00:00.000 0:01:50.812 32 4385 28 8 694 52 4 System
0:00:00.015 0:00:00.109 60 224 172 11 19 3 332 smss.exe
0:00:33.234 0:00:32.046 2144 33467 1980 13 396 14 556 csrss.exe
0:00:00.343 0:00:01.750 3684 6811 7792 13 578 20 580 winlogon.exe
0:00:00.078 0:00:01.734 1948 3022 1680 9 275 16 624 services.exe
0:00:00.218 0:00:03.515 1896 5958 3932 9 363 25 636 lsass.exe
0:00:00.015 0:00:00.078 80 804 592 8 25 1 812 vmacthlp.exe
0:00:00.093 0:00:00.359 1416 2765 3016 8 195 17 828 svchost.exe
0:00:00.062 0:00:00.453 1340 3566 1764 8 244 10 896 svchost.exe
0:00:00.828 0:01:16.593 9632 36387 11708 8 1206 59 1024 svchost.exe
0:00:00.046 0:00:00.640 1020 2315 1300 8 81 6 1100 svchost.exe
0:00:00.015 0:00:00.234 736 2330 1492 8 165 11 1272 svchost.exe
0:00:00.015 0:00:00.218 128 1959 3788 8 117 10 1440 spoolsv.exe
0:00:01.312 0:00:19.828 13636 35525 14732 8 575 19 1952 explorer.exe
0:00:00.250 0:00:00.937 956 1705 856 8 29 1 228 VMwareTray.exe
0:00:00.812 0:00:04.562 1044 4619 3800 8 165 4 240 VMwareUser.exe
 
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