This is a challenge when dealing with JSON. You can either force the data type in the CTAS statement (likely better option) or deal with the data type change in parquet table(s) by using CAST, etc. In the case of zip codes you need to consider if it will be 5 digits or the extended 5-4 digits to decide if the data type should be INT or VARCHAR.
Also look into the TYPEOF function, which you can use with CASE to deal with these types of issues. I prefer to deal with data issues as soon as possible in the pipeline, so the tables you create are consistent and clean. --Andries On 2/23/18, 12:04 PM, "Lee, David" <david....@blackrock.com> wrote: Using Drill's CTAS statements I've run into a schema inconsistency issue and I'm not sure how to solve it.. CREATE TABLE name [ (column list) ] AS query; If I have a directory called Cities which have JSON files which look like: a.json: { "city":"San Francisco", "zip":"94105"} { "city":"San Jose", "zip":"94088"} b.json: { "city":"Toronto ", "zip": null} { "city":"Montreal", "zip" null} If I create a parquet file out of the Cities directory I will end up with files called: 1_0_0.parquet through 1_5_1.parquet Now I got a problem: Most of the parquet files have a column type of char for zip. Some of the parquet files have a column type of int for zip because the zip value for a group of records was NULL.. This produces schema change errors later when trying to query the parquet directory. Is it possible for Drill to do a better job learning schemas across all json files in a directory before creating parquet? This message may contain information that is confidential or privileged. If you are not the intended recipient, please advise the sender immediately and delete this message. See https://urldefense.proofpoint.com/v2/url?u=http-3A__www.blackrock.com_corporate_en-2Dus_compliance_email-2Ddisclaimers&d=DwIFaQ&c=cskdkSMqhcnjZxdQVpwTXg&r=Q3Oz5l4W5TvDHNLpOqMYE2AgtKWFE937v89GEHyOVDU&m=xX9pt8fqAgZu6-OzbVwvpCjEh4kJpnqajJvMlRkLkZQ&s=hpMAe2P_obD6f_4QKWUE_yeIbxM6me3oniVH3btG2Eg&e= for further information. Please refer to https://urldefense.proofpoint.com/v2/url?u=http-3A__www.blackrock.com_corporate_en-2Dus_compliance_privacy-2Dpolicy&d=DwIFaQ&c=cskdkSMqhcnjZxdQVpwTXg&r=Q3Oz5l4W5TvDHNLpOqMYE2AgtKWFE937v89GEHyOVDU&m=xX9pt8fqAgZu6-OzbVwvpCjEh4kJpnqajJvMlRkLkZQ&s=TCbMg__Jd7CA-8aVdb8xaCCPLXmqWwRNk1mHMB5d7uo&e= for more information about BlackRock’s Privacy Policy. For a list of BlackRock's office addresses worldwide, see https://urldefense.proofpoint.com/v2/url?u=http-3A__www.blackrock.com_corporate_en-2Dus_about-2Dus_contacts-2Dlocations&d=DwIFaQ&c=cskdkSMqhcnjZxdQVpwTXg&r=Q3Oz5l4W5TvDHNLpOqMYE2AgtKWFE937v89GEHyOVDU&m=xX9pt8fqAgZu6-OzbVwvpCjEh4kJpnqajJvMlRkLkZQ&s=99fuo3ra5r022Cja5zizkZcv2vzuxNneLGJjKbwv6Kw&e=. © 2018 BlackRock, Inc. All rights reserved.