从文本字段中提取值以支持 Redshift 表中 SQL 中的 GROUP BY

Question

I have a Redshift table that essentially contains survey results that I'm trying to do some statistical analysis on (example data at end of question). For the purposes of this question we can assume the table has three columns: response , date_submitted and meta_data

The response column contains a simple 1 or 0 . The timestamp is the datetime when the survey was submitted. And the meta_data field is essentially a CSV text field with a list of key, value pairs.

Example row below

f1=v1, f2=v2, templateId=<someTemplateId>, ...

Most of this data I don't care about but the templateId is the value I want to pull out of meta_data . I would like to use templateId to GROUP BY all my rows so I can get summary statistics for each templateId . Long term this value should be extracted into its own column but given time constraints I am unable to update our data generating process for this and need to perform the analysis before that work can be done

Ultimatley the query I'd like to be able to do is

SELECT sum(response) FROM my_table GROUP BY <template_id>

Example Data

   reponse                    meta_data                  timestamp
0        0  f1=v1, f2=v2, templateId=77 2021-04-07 09:51:55.655793
1        0  f1=v1, f2=v2, templateId=55 2021-04-07 08:51:55.655793
2        1  f1=v1, f2=v2, templateId=77 2021-04-07 07:51:55.655793
3        1  f1=v1, f2=v2, templateId=77 2021-04-07 06:51:55.655793
4        1  f1=v1, f2=v2, templateId=66 2021-04-07 05:51:55.655793

To clarify the above... f1=v1, f2=v2, templateId=77 is the entry for meta_data in the first row

Answer 1

You should be able to use regexp_substr() :

select t.*,
       regexp_substr(meta_data, 'template_id=([^ ]+) ', 1, 1, 'e') as template_id
from t;