Catalog

Database persistence starts

Data persistence validation

In the last article, based on docker Installation of , We use enmotech The latest image of has been installed and started . Container deployment is very convenient , Uninstallation is easier . But this feature is like a double-edged sword , Bring convenience at the same time , There will be some shortcomings . Once the container is deleted , All data and configurations in the container will be lost . Even if you re run a new container , What we get is just a new initial state database .

therefore , For data that needs persistence, such as databases , We also need to see how to prevent the loss of data caused by the deletion or damage of containers . stay openGauss In the database , This function is achieved by specifying relevant parameters .

Database persistence starts

Our environment for this persistence test is based on the previous article stay docker Deploy openGauss. Let's delete the container instance we started last time .

[[email protected] docker]# docker ps -a 
CONTAINER ID   IMAGE                      COMMAND                  CREATED      STATUS      PORTS      NAMES 
573ea1edffb8   enmotech/opengauss:3.0.0   "entrypoint.sh gauss…"   3 days ago   Up 3 days   5432/tcp   opengauss 
[[email protected] docker]# docker stop 573ea1edffb8 
573ea1edffb8 
[[email protected] docker]# docker rm 573ea1edffb8 
573ea1edffb8

The following command uses the original opengauss Mirror starts a container ：

docker run --name opengauss --privileged=true -d -e [email protected] -v /enmotech/opengauss:/var/lib/opengauss -p 15432:5432  enmotech/opengauss:3.0.0

For the explanation of other parameters, please refer to the previous installation . Here we mainly focus on -p   -v Two parameters .

• -p Parameters ：openGauss The default listening of starts in the container 5432 On port , If you want to access the database from outside the container , You need to in docker run When it's time to specify -p Parameters . For example, the above command will allow you to use 15432 The port accesses the database outside the container . After the above command starts the container database normally , It can be done through external gsql Database access .
•  -v Parameters ： Appoint Docker in openGauss All data files for , It's in the container /var/lib/opengauss Catalog , The host is /enmotech/opengauss Catalog . If the host's /enmotech/opengauss If it doesn't exist ,docker Automatically created , But it must be an absolute path .Docker Have read and write permission to it .

View the database directory inside the container . Here's the picture , Already in the container /var/lib/opengauss Created data Catalog .

[[email protected] docker]# docker ps 
CONTAINER ID   IMAGE                      COMMAND                  CREATED              STATUS              PORTS                                         NAMES 
89747134cd4d   enmotech/opengauss:3.0.0   "entrypoint.sh gauss…"   About a minute ago   Up About a minute   0.0.0.0:15432->5432/tcp, :::15432->5432/tcp   opengauss 
[[email protected] docker]# docker exec -it 89747134cd4d /bin/bash 
[email protected]:/# cd /var/lib/opengauss/data/ 
[email protected]:/var/lib/opengauss/data# ls 
asp_data       gs_gazelle.conf     pg_audit     pg_errorinfo   pg_location   pg_notify    pg_snapshots  PG_VERSION            postmaster.opts      undo 
base           gs_profile          pg_clog      pg_hba.conf    pg_log        pg_perf      pg_stat_tmp   pg_xlog               postmaster.pid 
gaussdb.state  gswlm_userinfo.cfg  pg_csnlog    pg_ident.conf  pg_logical    pg_replslot  pg_tblspc     postgresql.conf       postmaster.pid.lock 
global         mot.conf            pg_ctl.lock  pg_llog        pg_multixact  pg_serial    pg_twophase   postgresql.conf.lock  sql_monitor 

Let's check the database directory on the host . Here's the picture , Already on the host /enmotech/opengauss Created data Catalog . You can see that the data in the container has been stored in the operating system .

Data persistence validation

Now let's build a table 、 Insert data to see whether the persistent storage of data can be completed .
1. Into the container , Log in to the database .

[[email protected] docker]# docker ps 
CONTAINER ID   IMAGE                      COMMAND                  CREATED              STATUS              PORTS                                         NAMES 
89747134cd4d   enmotech/opengauss:3.0.0   "entrypoint.sh gauss…"   About a minute ago   Up About a minute   0.0.0.0:15432->5432/tcp, :::15432->5432/tcp   opengauss 
[[email protected] docker]# docker exec -it 89747134cd4d /bin/bash 
[email protected]:/var/lib/opengauss/data# su - omm 
[email protected]:~$ gsql 
omm=# 

Is a new database instance , Look at me During previous installation Test the user created wxx Are you there? . It is as expected , It just doesn't exist . Because there was no persistent startup during the previous operation .

2. Create table test1, And then insert the data .

create table test1(id int,name varchar(20)); 
INSERT INTO test1 VALUES (1, 'oligei');

3. Close the database .

[email protected]:~$ gs_ctl stop -D /var/lib/opengauss/data/ 
[2022-07-19 02:46:25.253][423][][gs_ctl]: gs_ctl stopped ,datadir is /var/lib/opengauss/data 
waiting for server to shut down....[[email protected] docker]#

4. Start database

[[email protected] docker]# docker start 89747134cd4d 
89747134cd4d 
[[email protected] docker]# docker exec -it 89747134cd4d /bin/bash 
[email protected]:/# su - omm 
[email protected]:~$ gsql

5. Verify that after the container restarts , The original data is still .

 6. Just restart , It's not surprising that the data was not lost . We pay more attention to container deletion .

[[email protected] docker]# docker stop 89747134cd4d 
89747134cd4d 
[[email protected] docker]# docker rm 89747134cd4d 
89747134cd4d 
[[email protected] docker]# docker exec -it 89747134cd4d /bin/bash 
Error: No such container: 89747134cd4d

You can see that the original container has been deleted successfully .
7. Now restart , See if persistence is successful . You still need to use the previously specified storage path .

[[email protected] docker]# docker run --name opengauss --privileged=true -d -e [email protected] -v /enmotech/opengauss:/var/lib/opengauss -p 15432:5432  enmotech/opengauss:3.0.0 
[[email protected] docker]# docker ps 
[[email protected] docker]# docker exec -it 74b94a7bda80 /bin/bash 
[email protected]:/# su - omm 
[email protected]:~$ gsql 
omm=# select * from test1;

Results previous figure .

It can also be seen from the above figure , The original table records still exist , Database persistence succeeded .

openGauss: A high performance 、 High security 、 Highly reliable enterprise level open source relational database .

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