[[faking-it]] === Faking Index per User with Aliases To keep our design simple and clean, we would((("scaling", "faking index-per-user with aliases")))((("aliases, index")))((("index aliases"))) like our application to believe that we have a dedicated index per user--or per forum in our example--even if the reality is that we are using one big <<shared-index,shared index>>. To do that, we need some way to hide the `routing` value and the filter on `forum_id`. Index aliases allow us to do just that. When you associate an alias with an index, you can also specify a filter and routing values: [source,json] ------------------------------ PUT /forums/_alias/baking { "routing": "baking", "filter": { "term": { "forum_id": "baking" } } } ------------------------------ Now, we can treat the `baking` alias as if it were its own index. Documents indexed into the `baking` alias automatically get the custom routing value applied: [source,json] ------------------------------ PUT /baking/post/1 <1> { "forum_id": "baking", <1> "title": "Easy recipe for ginger nuts", ... } ------------------------------ <1> We still need the `forum_id` field for the filter to work, but the custom routing value is now implicit. Queries run against the `baking` alias are run just on the shard associated with the custom routing value, and the results are automatically filtered by the filter we specified: [source,json] ------------------------------ GET /baking/post/_search { "query": { "match": { "title": "ginger nuts" } } } ------------------------------ Multiple aliases can be specified when searching across multiple forums: [source,json] ------------------------------ GET /baking,recipes/post/_search <1> { "query": { "match": { "title": "ginger nuts" } } } ------------------------------ <1> Both `routing` values are applied, and results can match either filter.