getredash/redash

Query with table with CLOB or BLOB fields is not running in Redash.

Open

#5,546 opened on Jul 26, 2021

View on GitHub
 (1 comment) (0 reactions) (0 assignees)Python (24,845 stars) (4,236 forks)batch import
Query Runner: Oracleenhancementhelp wanted

Description

Issue Summary

Query with table with CLOB or BLOB fields is not running in Redash.

Steps to Reproduce

  1. Query any table with a Clob or Blob column: Select * from Table;
  2. See error: Error running query < cx_Oracle.LOB obect at 0x7f3deb5080> is not json serializable.

Technical details:

  • Redash Version: redash:8.0.2.b37747
  • Browser/OS:
  • How did you install Redash:

Contributor guide

Tech stack
pythonsql
Domain
backenddatabase
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic Python knowledgeFamiliarity with Oracle DB and cx Oracle
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
The error 'cx Oracle.LOB object is not JSON serializable' indicates that when Redash fetches query results from Oracle, it does not handle CLOB and BLOB fields. Investigate the Oracle data source connector in Redash, likely in files under 'redash/query runner/' or similar. Look for how other data types like strings or numbers are serialized to JSON, and add a handler for cx Oracle.LOB objects, possibly by using the .read() method to extract the content. Check if there are existing tests for Oracle query results.