AUTOLOAD (JANUS DEFINE parameter): Difference between revisions
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<span class="pageSubtitle">Automatically reload table definitions on an SDS port</span> | |||
<span class="pageSubtitle" | |||
<var>AUTOLOAD</var> is a parameter on <var>[[JANUS DEFINE]]</var>, which defines and sets characteristics of a Janus port. | <var>AUTOLOAD</var> is a parameter on <var>[[JANUS DEFINE]]</var>, which defines and sets characteristics of a Janus port. | ||
This parameter | This parameter indicates that the incore copy of Janus tables are to be reloaded at the first request subsequent to a table redefinition. This eliminates the need to issue JANUS RELOAD commands to reload table definitions after changes have been made. | ||
<var>AUTOLOAD</var> does have a few disadvantages, however. First, if several table definitions are being changed while SQL requests are being processed on a port, Janus might end up performing the reload process several times where issuing a JANUS RELOAD command at the end of all the changes would result in a single reload. Doing multiple reloads could be a significant expense if the number of <var>[[JANCAT (JANUS DEFINE parameter)|JANCAT]]</var> table definitions is large. The other disadvantage of <var>AUTOLOAD</var> is that the reload doesn't happen until a request arrives on the port. This means that the user issuing the request could encounter a significant delay as the Janus port is reloaded. A JANUS RELOAD command before the request comes in would ensure that the table definitions would already be loaded so no extra delay would be encountered. | <var>AUTOLOAD</var> does have a few disadvantages, however. First, if several table definitions are being changed while SQL requests are being processed on a port, Janus might end up performing the reload process several times where issuing a <code>JANUS RELOAD</code> command at the end of all the changes would result in a single reload. Doing multiple reloads could be a significant expense if the number of <var>[[JANCAT (JANUS DEFINE parameter)|JANCAT]]</var> table definitions is large. The other disadvantage of <var>AUTOLOAD</var> is that the reload doesn't happen until a request arrives on the port. This means that the user issuing the request could encounter a significant delay as the Janus port is reloaded. A <code>JANUS RELOAD</code> command before the request comes in would ensure that the table definitions would already be loaded so no extra delay would be encountered. | ||
Note that it is perfectly valid to issue a JANUS RELOAD command on an <var>AUTOLOAD</var> port. | Note that it is perfectly valid to issue a JANUS RELOAD command on an <var>AUTOLOAD</var> port. | ||
Valid only for <var>[[JANUS DEFINE#type|SDS]]</var> (also known as <var> | Valid only for <var>[[JANUS DEFINE#type|SDS]]</var> (also known as <var>OMNI</var> or <var>OAS</var>) ports. | ||
==See also== | ==See also== | ||
Latest revision as of 18:17, 8 June 2016
Automatically reload table definitions on an SDS port
AUTOLOAD is a parameter on JANUS DEFINE, which defines and sets characteristics of a Janus port.
This parameter indicates that the incore copy of Janus tables are to be reloaded at the first request subsequent to a table redefinition. This eliminates the need to issue JANUS RELOAD commands to reload table definitions after changes have been made.
AUTOLOAD does have a few disadvantages, however. First, if several table definitions are being changed while SQL requests are being processed on a port, Janus might end up performing the reload process several times where issuing a JANUS RELOAD command at the end of all the changes would result in a single reload. Doing multiple reloads could be a significant expense if the number of JANCAT table definitions is large. The other disadvantage of AUTOLOAD is that the reload doesn't happen until a request arrives on the port. This means that the user issuing the request could encounter a significant delay as the Janus port is reloaded. A JANUS RELOAD command before the request comes in would ensure that the table definitions would already be loaded so no extra delay would be encountered.
Note that it is perfectly valid to issue a JANUS RELOAD command on an AUTOLOAD port.
Valid only for SDS (also known as OMNI or OAS) ports.