[DRILL-8169] Add UDFs to HTTP Plugin to Facilitate Joins

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.20.0
• Fix Version/s: 1.21.0
• Component/s: Storage - Other
• Assignee: Charles Givre
• Reporter: Charles Givre
• Created: 16/Mar/22 18:16
• Updated: 26/May/22 14:02
• Resolved: 26/May/22 14:02

Description

There are some situations where a user might want to join data with an API result and the pushdowns prevent that from happening. The main situation where this happens is when
an API has parameters which are part of the URL AND these parameters are dynamically populated via a join.

In this case, there are two functions `http_get_url` and `http_get` which you can use to faciliate these joins.

• `http_get('<storage_plugin_name>', <params>)`: This function accepts a storage plugin as input and an optional list of parameters to include in a URL.
• `http_get_url(<url>, <params>)`: This function works in the same way except that it does not pull any configuration information from existing storage plugins.

1. 1. 1. Example Queries
         Let's say that you have a storage plugin called `github` with an endpoint called `repos` which points to the url: https://github.com/orgs/\{org}/repos. It is easy enough to
         write a query like this:

```sql
SELECT *
FROM github.repos
WHERE org='apache'
```
However, if you had a file with organizations and wanted to join this with the API, the query would fail. Using the functions listed above you could get this data as follows:

```sql
SELECT http_get('github.repos', `org`)
FROM dfs.`some_data.csvh`
```
or
```sql
SELECT http_get('https://github.com/orgs/{org}/repos', `org`)
FROM dfs.`some_data.csvh`
```

• • WARNING: This functionality will execute an HTTP Request FOR EVERY ROW IN YOUR DATA. Use with caution. **