Understanding catalog in DB2 Databases

Guidance:InDB2 databaseWe often encounterCatalogMany people are not very familiar with this word, and catalog is difficult to understand. Specifically, cataloguing includes cataloguing nodes and cataloguing databases. If you want to understand the cataloguing, let me briefly introduce the architecture of the DB2 database. The biggest concept in the DB2 database is the system (node), that is, the host. Below is an instance, below the instance is the database, then the tablespace, and then the database object. Now suppose you have a database server on p570, and you have a client on windows, linux, or any platform. Now you want to establish a client-to-server connection, what are the specific steps?

Step 2:

You must identify the remote server on the client machine. How can this problem be solved? The catalog Method Used in DB2 is to write a remote server in a local client file by cataloguing:

Db2 catalog tcpip node p570 remote 172.10.10.10 server 50000

In the preceding command, the p570 is a node name (which must be unique on a machine), the remote server is followed by the server IP address, and the server is the port number corresponding to the instance on the remote server. DB2 records the remote server information in the local SQLNODIR file in this way. Therefore, the cataloguing node maps the remote server to the local server, the records in SQLNODIR can be used to locate the remote server and instance, similar to the address pointer pointing to the remote server and instance.

Step 2:

After the remote server IP address and instance are catalogued, the database under the instance should be catalogued locally in step 2.

Db2 catalog db REMOTEDB at node p570

In this command, REMOTEDB is the database under the remote instance, and p570 is the name of the target node in step 1.

After this command is executed, the remote database information is recorded in the local SQLDBDIR file, which can be understood as ing the database under the remote server instance to a local alias.

The preceding example shows that the client and server are not on the same machine, and the database is catalogued through the cataloguing node to connect the client to the database on the server. If the client is connected to the same machine, at this time, do not display the cataloguing nodes. However, when we create an instance on the server, there is an implicit process of cataloging the instance locally, assume that an instance named db2inst1 is created on p570, there is an implicit

Db2 catalog local node db2inst1 instance db2inst1 system p570 ostype aix steps,

Similarly, when you create a database MYDB under db2inst1, there is an implicit catalog Database step:

Steps for db2 catalog db mydb at node db2inst1

Now you can understand the catalog, which is the purpose of establishing a database connection from the client to the server locally or remotely.

This article introduces the catalog knowledge in the DB2 database, which may not be comprehensive. I hope you will continue to pay attention to our website to provide more detailed knowledge points in the future.