View the Oracle shared memory segment --------- IPCS in Oracle 11g

A long time ago, I gave a lecture and used the command ipcs to find that the Oracle Sharing Section is small, as shown below:

Oracle @ mydb ~] $ Ipcs-

------ Shared Memory Segments --------
Key shmid owner perms bytes nattch status
0x00000000 32768 root 644 72 2
0x00000000 65537 root 644 16384 2
0x00000000 98306 root 644 280 2
0x00000000 1409028 oracle 640 4096 0
0x00000000 1441797 oracle 640 4096 0
0x079918e8 1474566 oracle 640 4096 0

------ Semaphore Arrays --------
Key semid owner perms nsems
0x87a36da4 1343489 oracle 640 154

------ Message Queues --------
Key msqid owner perms used-bytes messages

Today, I suddenly think of it. I just have time to summarize it:

The above shows that the Oracle shared memory segment is only 4096 bytes, which is too small. Oh, yes, I am Oracle11g:

Sys @ OCM> select * from v $ version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0-64bit Production
PL/SQL Release 11.2.0.3.0-Production
CORE 11.2.0.3.0 Production
TNS for Linux: Version 11.2.0.3.0-Production
NLSRTL Version 11.2.0.3.0-Production

The lifecycle 11g memory management uses two new parameters:

Sys @ OCM> show parameter memory

NAME TYPE VALUE
-----------------------------------------------------------------------------
Hi_shared_memory_address integer 0
Memory_max_target big integer 1G
Memory_target big integer 0
Shared_memory_address integer 0

Will it be that the parameter memory_max_target is playing a strange role? Shut it down and try. Here I set it to 0 and then restart the database.

Sys @ OCM> alter system set memory_max_target = 0 scope = spfile;

System altered.

Sys @ OCM> startup force;
ORACLE instance started.

Total System Global Area 943669248 bytes
Fixed Size 2234000 bytes
Variable Size 541067632 bytes
Database Buffers 394264576 bytes
Redo Buffers 6103040 bytes
Database mounted.
Database opened.

Let's look at the shared memory:

[Oracle @ mydb ~] $ Ipcs-

------ Shared Memory Segments --------
Key shmid owner perms bytes nattch status
0x00000000 32768 root 644 72 2
0x00000000 65537 root 644 16384 2
0x00000000 98306 root 644 280 2
0x00000000 1802244 oracle 640 4096 0
0x00000000 1835013 oracle 640 4096 0
0x079918e8 1867782 oracle 640 4096 0

------ Semaphore Arrays --------
Key semid owner perms nsems
0x87a36da4 1736705 oracle 640 154

------ Message Queues --------
Key msqid owner perms used-bytes messages

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