[GitHub] cgivre commented on issue #1539: DRILL-6847: Add Query Metadata to RESTful Interface

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cgivre commented on issue #1539: DRILL-6847: Add Query Metadata to RESTful Interface
URL: https://github.com/apache/drill/pull/1539#issuecomment-439064781
 
 
   HI @kkhatua 
   A few things.  First re: breaking backward compatibility.  Since the RESTful interface returns JSON KV pairs, and since all this is doing is introducing an additional key (metadata) which contains the column types, I don't think it will break anything since it isn't doing anything to the existing keys.  No real way to know unless a lot of people complain, but the tools which I use that use the RESTful interface are not affected.
   
   Secondly, regarding star queries, I did try a few on my local machine and you get a dump of all the column types. IE if your data contains 4 columns and you do a `SELECT *` you get:
   
   ```
     "metadata": [
       "INT",
       "VARCHAR",
       "VARCHAR",
       "VARCHAR"
     ],
   ```
   Since this code gets called when results are returned, I don't think schema inconsistencies matter.  IE if the query fails due to schema inconsistencies, you won't get metadata, and if it succeeds you get the results. 
   
   @arina-ielchiieva Would you like to see additional arrays with precision and scale with null values if it is not needed.  IE 
   ```
   "scale": [
   4,
   null,
   null,
   null
   ]
   ```

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