How to create sitecore custom index ?

With Sitecore, If there are lots of data on the instance where search needed, then Sitecore default index will not be good because it will be time and memory consuming.

In that case - creating custom index will be better approach which contains only searched items.

Let's start with creating solr custom index

Go to your solr installed location by copying sitecore_web_index and rename with sitecore_custom_index [<instancename>_web_index - so don't confused with sitecore]

once copied, then open core.properties and update name property under this directory as below screenshot

after above changes, restart solr service.

Now go to path \App_Config\Sitecore\ContentSearch and copy Sitecore.ContentSearch.Solr.Index.Web.config and rename with Sitecore.ContentSearch.Solr.Index.Custom.onfig as below

once file created open update settings for 

indexname, rootpath, which items wanted to include and exclude in index. as below

Let me know if feel any issue or feedback.