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Chapter 9. Tuning Database Link Performance
Database link performance can be improved through changes to the Directory Server's connection and thread management.
9.1. Managing Connections to the Remote Server
Each database link maintains a pool of connections to a remote server. The connections to optimize resources can be configured for the directory.
9.1.1. Managing Connections to the Remote Server Using the Console
- Select the Configuration tab, expand the Data folder in the left pane, and select the suffix, then the database link to change.
- Click the Limits and Controls tab in the right navigation pane.
- In the Connection Management section, make changes to any of the following fields:
- Maximum TCP connection(s). The maximum number of TCP connections that the database link establishes with the remote server. The default value is
3connections. - Bind timeout. Amount of time, in seconds, before the database link's bind attempt times out. The default value is
15seconds. - Maximum binds per connection. Maximum number of outstanding bind operations per TCP connection. The default value is
10outstanding bind operations per connection. - Time out before abandon (sec). Number of seconds before the server checks to see if a timed-out connection should be abandoned. The default value is
1second. - Maximum LDAP connection(s). Maximum number of LDAP connections that the database link establishes with the remote server. The default value is
10connections. - Maximum bind retries. Number of times a database link attempts to bind to the remote server. A value of
0indicates that the database link will try to bind only once. The default value is3attempts. - Maximum operations per connection. Maximum number of outstanding operations per LDAP connection. The default value is
2operations per connection. - Connection lifetime (sec). How long a connection made between the database link and remote server remains open. Connections between the database link and the remote server can be kept open for an unspecified time or closed after a specific period of time. It is faster to keep the connections open, but it uses more resources. For slow connections, it may be desirable to limit the connection time. A value of
0indicates there is no limit. By default, the value is set to0.
9.1.2. Managing Connections to the Remote Server from the Command Line
Use
ldapmodify to add connection attributes to the database link entry.
The default connection management attributes are stored in the following entry:
cn=default instance config,cn=chaining database,cn=plugins,cn=config
The connection management attributes for a specific database link are stored in the following entry:
cn=database_link,cn=chaining database,cn=plugins,cn=config
The connection management attributes specified in this entry take precedence over the attributes specified in the
cn=default instance config entry.
Table 9.1. Database Link Connection Management Attributes
| Attribute Name | Description |
|---|---|
| nsOperationConnectionsLimit | Maximum number of LDAP connections that the database link establishes with the remote server. The default value is 20 connections per database link instance. |
| nsBindConnectionsLimit | Maximum number of TCP connections that the database link establishes with the remote server. The default value is 3 connections. |
| nsConcurrentOperationsLimit | Maximum number of outstanding operations per LDAP connection. The default value is 2 operations per connection. |
| nsConcurrentBindLimit | Maximum number of outstanding bind operations per TCP connection. The default value is 10 outstanding bind operations. |
| nsBindRetryLimit | Number of times a database link attempts to bind to the remote server. A value of zero (0) indicates that the database link will try to bind only once. The default value is 3 attempts. |
| nsConnectionLife | Connection lifetime, in seconds. Connections between the database link and the remote server can be kept open for an unspecified time or closed after a specific period of time. It is faster to keep the connections open, but it uses more resources. For example, it may be wise to limit the connection time for a slow connection. A value of 0 indicates there is no limit. By default, the value is set to 0. When the value is 0 and there is a list of failover servers in the nsFarmServerURL attribute, the first server is never contacted after failover to the alternate server. The default value is 0 seconds. |
| nsBindTimeout | Amount of time, in seconds, before the bind attempt times out. The default value is 15 seconds. |
| nsAbandonedSearchCheckInterval | Number of seconds that pass before the server checks for abandoned operations. The default value is 1 second. |
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