Football and oracle series (1): 32-way zhoudianbing, overall view of group A Brazil smon process of oracle32 process Alliance

Statement:

This is not a technical document. Since I have learned a few tricks about oracle, I cannot afford to sell it to anyone. Just after a meal, I joined several friends in the library. It is just a bit humorous and it can also be used to make fun of others.

At the same time, I have forgotten a lot of oracle knowledge points in recent months. In order to reproduce the knowledge points, I am inspired to publish them in a free form, the examples or stories listed in this article are bound to be far-fetched in terms of technical connection. It's just a note from cainiao. Don't use it as a technical article! I have read and laughed.

Welcome to shoot bricks. This will be the biggest motivation for my growth.

Clue 1: 32-way zhuhou dianbing, oracle32 process Alliance

Group A: Overview of the Brazilian SMON Process

Brazil has always been active in the world as a strong person. It is very important like the SMON process in oracle. Once an instance crashes, it must be restored by SMON. If one day the football game is lost (it should not appear, haha), it is necessary for Brazil, which has the name of the football kingdom, to turn the storm!

Look at our friends in the same group as Brazil. Croatia is like a temporary tablespace. Europe has arrived in America. Haha, you know...

Mexico is like a tablespace in a rollback segment, so that we can remember the historical performance of the North American team, just as the rollback segment can maintain read consistency.

In the end, Cameroon is left. This exciting team has to say that the turmoil in the country will have some impact on the team. At the same time, we are even more fortunate that the turmoil will not eliminate a country's love for football, however, after all, the instance is inferior to other teams. compare it to the free space between instances. We hope to use it again one day and become more powerful.

SMON process:

Brief description:

Important background processes, responsible for instance recovery at instance startup. It also clears temporary segments that are no longer in use. In a parallel server environment, this process recovers faulty instances and faulty CPUs. SMON consumes a lot of CPU. SMON will be periodically awakened and executed to deal with the following tasks. It is like Brazil, the host of the 2014 World Cup, with a strong football skill, but at the same time, it is busy planning the World Cup, O (∩) O Haha ~

Work details:

1. Clear temporary tablespace

For example, when an index is created, the extended area allocated to the index during creation is identified as temporary. If the create index session is interrupted due to exceptions for some reason, SMON is responsible for clearing the session. SMON will also process temporary extension zones created by other operations.

2. Clear rollback segments

SMON automatically contracts the rollback segment to its optimal size (provided that it has been set ).

3. Merge idle Space

For example, if you are using a data dictionary to manage tablespaces, SMON is responsible for concatenating the extent that is located in the tablespace and is close to each other into a large idle extended area (provided that the default pctincrease is set as a non-zero storage sub-statement to manage the tablespace in the dictionary ). ).

4. Restore unavailable file transactions to activities

For example, if the file may be unavailable or not loaded to the disk. SMON will restore it. This is similar to when the database is started. Files cannot be used for recovery. SMON restores the faulty transactions that are skipped during instance recovery.

5. instance recovery for RAC faulty nodes

For example, when a node instance crashes in a cluster, the other nodes in the cluster start the redo log file of the faulty instance to restore all data of the faulty instance.

6. Clear OBJ $

SMON will be responsible for deleting processes that are not in need of the row.

7. Offline rollback segments

When the rollback segment of an active transaction needs to be offline or unavailable in practical applications, the rollback segment is not actually offline and is marked as "offline ", in background processes, SMON periodically takes it offline until it is completed.

[08: 07: 05oracle @ gc1] $ ps-ef | grep 'ora _. * '; -- check which processes are running.

-- Process naming format: ora _ process name_instance name
Oracle 3075 1 0? 00:00:00 ora_pmon_PROD
Oracle 3077 1 0? 00:00:00 ora_vktm_PROD
Oracle 3081 1 0? 00:00:00 ora_gen0_PROD
Oracle 3083 1 0? 00:00:00 ora_diag_PROD
Oracle 3085 1 0? 00:00:00 ora_dbrm_PROD
Oracle 3087 1 0? 00:00:00 ora_psp0_PROD
Oracle 3089 1 0? 00:00:00 ora_dia0_PROD
Oracle 3091 1 0? 00:00:00 ora_mman_PROD
Oracle 3093 1 0? 00:00:00 ora_dbw0_PROD
Oracle 3095 1 0? 00:00:00 ora_lgwr_PROD
Oracle 3097 1 0? 00:00:00 ora_ckpt_PROD
Oracle 3099 1 0? 00:00:00 ora_smon_PROD
Oracle 3101 1 0? 00:00:00 ora_reco_PROD
Oracle 3103 1 1? 00:00:00 ora_mmon_PROD
Oracle 3105 1 0? 00:00:00 ora_mmnl_PROD
Oracle 3107 1 0? 00:00:00 ora_d000_PROD
Oracle 3109 1 0? 00:00:00 ora_d001_PROD
Oracle 3111 1 0? 00:00:00 ora_d002_PROD
Oracle 3113 1 0? 00:00:00 ora_s000_PROD
Oracle 3115 1 0? 00:00:00 ora_s001_PROD
Oracle 3117 1 0? 00:00:00 ora_s002_PROD
Oracle 3119 1 0? 00:00:00 ora_s003_PROD
Oracle 3121 1 0? 00:00:00 ora_s004_PROD
Oracle 3123 1 0? 00:00:00 ora_s005_PROD
Oracle 3125 1 0? 00:00:00 ora_s006_PROD
Oracle 3127 1 0? 00:00:00 ora_s007_PROD
Oracle 3129 1 0? 00:00:00 ora_s008_PROD
Oracle 3131 1 0? 00:00:00 ora_s009_PROD
Oracle 3139 1 0? 00:00:00 ora_qmnc_PROD
Oracle 3153 1 1? 00:00:00 ora_cjq0_PROD
Oracle 3183 1 10? 00:00:02 ora_j000_PROD
Oracle 3185 1 0? 00:00:00 ora_j001_PROD
Oracle 3189 1 2? 00:00:00 ora_j003_PROD
Oracle 3191 1 0? 00:00:00 ora_j004_PROD
Oracle 3193 1 0? 00:00:00 ora_q000_PROD
Oracle 3195 1 0? 00:00:00 ora_q001_PROD

I think that the comparison between football and oracle is first caused by my personal interests, and secondly, I think it is more appropriate, because football is the sports with the largest venue and the most participants in the competitive sports, there is a clear and vivid correspondence with oracle's complex knowledge system.

This series will not be based on the narration of time or plot, but will be randomly produced by the author, presented in a free style.