HOW TO: Find and Kill long running queries in Snowflake?

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1. Introduction

The Snowflake INFORMATION_SCHEMA consists of a set of system-defined views and table functions that provide extensive metadata information about the objects created in your account.

There is a table function that is made available under Snowflake information schema which provides historical information of queries triggered which helps in finding and killing the long running queries.

2. QUERY_HISTORY table function

The QUERY_HISTORY table function can be used to query Snowflake query history along various dimensions. The functions returns query activity within the last 7 days.

There is a family of table functions available under QUERY_HISTORY

  • QUERY_HISTORY: Returns queries within a specified time range.
  • QUERY_HISTORY_BY_SESSION:  Returns queries within a specified session and time range.
  • QUERY_HISTORY_BY_USER:  Returns queries submitted by a specified user within a specified time range.
  • QUERY_HISTORY_BY_WAREHOUSE:  Returns queries executed by a specified warehouse within a specified time range.

3. Retrieving query history using QUERY_HISTORY table function

The below query retrieves up to the last 100 queries run by the current user or run by any user on any warehouse on which the current user has the MONITOR privilege.

select *
from table(information_schema.query_history())
order by start_time;

4. Finding long queries within a time range

4.1. Without arguments in table function

The below query retrieves the long running queries which ran more than 5 minutes in last 1 hour.

select
    query_id,
    query_text,
    user_name,
    warehouse_name,
    start_time,
    end_time,
    datediff(second, start_time, end_time) as run_time_in_seconds
from table(information_schema.query_history())
where datediff(minute, start_time, end_time) > 5
and start_time > dateadd(hour, -1, current_timestamp())
order by start_time;

4.2. With arguments in table function

Alternatively the above query can also written by passing arguments (END_TIME_RANGE_START, END_TIME_RANGE_END)  to the QUERY_HISTORY table function as shown below.

select
    query_id,
    query_text,
    user_name,
    warehouse_name,
    start_time,
    end_time,
    datediff(second, start_time, end_time) as run_time_in_seconds
from table(information_schema.query_history(
    END_TIME_RANGE_START => dateadd(hour,-1,current_timestamp()),
    END_TIME_RANGE_END => current_timestamp() ))
where datediff(minute, start_time, end_time) > 5
order by start_time;

The arguments in table function are not mandatory. If END_TIME_RANGE_END is not specified, the function returns all queries, including those that are still running currently.

The below query retrieves the queries started in last 5 minutes and still running.

select
    query_id,
    query_text,
    user_name,
    warehouse_name,
    start_time,
    datediff(second, start_time, current_timestamp) as run_time_in_seconds
from table(information_schema.query_history(END_TIME_RANGE_START => dateadd(minute, -5, current_timestamp)))
where execution_status='RUNNING'
order by start_time;

5. Finding long running queries by User

The below query retrieves the queries started in last 5 minutes and still running by user named “TONY”. The user name is passed through the argument USER_NAME to the QUERY_HISTORY_BY_USER table function.

select
    query_id,
    query_text,
    user_name,
    warehouse_name,
    start_time,
    datediff(second, start_time, current_timestamp) as run_time_in_seconds
from table(information_schema.query_history_by_user(USER_NAME => 'TONY'))
where execution_status='RUNNING'
order by start_time;

Arguments used in QUERY_HISTORY table function can be used in all of its family of table functions. Refer the example below.

6. Finding long running queries by Warehouse

The below query retrieves the queries which are triggered in last 1 hour and still running on warehouse named “’COMPUTE_WH”. The warehouse name is passed through the argument WAREHOUSE_NAME to the QUERY_HISTORY_BY_ WAREHOUSE table function.

select
    query_id,
    query_text,
    user_name,
    warehouse_name,
    start_time,
    datediff(second, start_time, current_timestamp) as run_time_in_seconds
from table(information_schema.query_history_by_warehouse(
    END_TIME_RANGE_START => dateadd(hour,-1,current_timestamp()),
    END_TIME_RANGE_END => current_timestamp(),
    WAREHOUSE_NAME => 'COMPUTE_WH'))
where execution_status='RUNNING'
order by start_time;

7. Killing a long running query in Snowflake using SYSTEM$CANCEL_QUERY

SYSTEM$CANCEL_QUERY kills/cancels the specified query (or statement) if it is currently active/running. The id of the query can be extracted by using the queries shared above.

select system$cancel_query(‘<query_id>’);

A user can cancel their own running SQL queries. Cancelling queries executed by another user requires a role with one of the following privileges.

  • OWNERSHIP on the user who executed the query.
  • OPERATE or OWNERSHIP on the warehouse that is running the query.

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