Issue Summary
We have seen queries not honoring the LIMIT 1000
Analysis
When redash attempts to apply the limit in the python backend it only add the LIMIT when the query_is_select_no_limit return true. For queries that Start with a CTE statement
example
with redshift_tables as
(select table_id, schema, name from de.tables)
select table_id, schema, name
from redshift_tables
The function below is returning false since parsed_query.tokens[0].value.upper() != "SELECT is returning True
.def query_is_select_no_limit(query):
parsed_query = sqlparse.parse(query)[0]
last_keyword_idx = find_last_keyword_idx(parsed_query)
# Either invalid query or query that is not select
if last_keyword_idx == -1 or parsed_query.tokens[0].value.upper() != "SELECT":
return False
no_limit = parsed_query.tokens[last_keyword_idx].value.upper() != "LIMIT" \
and parsed_query.tokens[last_keyword_idx].value.upper() != "OFFSET"
return no_limit
For queries that don’t start with a CTE (normal select) the LIMIT works
Workaround
I am not sure there is even if we create multiple statement the last statement is honored. Changing the function to parsed_query.tokens[0].value.upper() not in ("SELECT","WITH") fixes the issue but I have not done any rigorous testing or even run the unit tests
Technical details:
- Redash Version: 10
- Browser/OS: Chrome
- How did you install Redash: in AWS ECS (Docker image)
