How to drop temp tables created in snowflake

问题

I am loading data through ODI into snowflake temp tables created with c$ needs to be dropped after load successful,how to drop those temp tables appreciate your suggestion

回答1:

If you still need this, I wrote a stored procedure that will take a list of SQL generated dynamically and execute the lines one at a time. You can use it to run any list of generated SQL statements resulting from a select query, including dropping all tables matching a pattern such as c$%. First, here's the stored procedure:

create or replace procedure RunBatchSQL(sqlCommand String)
returns string
language JavaScript
as
$$
/**
 * Stored procedure to execute multiple SQL statements generated from a SQL query
 * Note that this procedure will always use the column named "SQL_COMMAND"
 *
 * @param {String} sqlCommand: The SQL query to run to generate one or more SQL commands 
 * @return {String}: A string containing all the SQL commands executed, each separated by a newline. 
 */
      cmd1_dict = {sqlText: SQLCOMMAND};
      stmt = snowflake.createStatement(cmd1_dict);

      rs = stmt.execute();

      var s = '';

      while (rs.next())  {
          cmd2_dict = {sqlText: rs.getColumnValue("SQL_COMMAND")};
          stmtEx = snowflake.createStatement(cmd2_dict);
          stmtEx.execute();
          s += rs.getColumnValue(1) + "\n";
          }

      return s;

$$

You can use this stored procedure to run any dynamically generated SQL statements in batch using the following script. Run the topmost query and it will be obvious what running the stored procedure with that query test as the parameter will do:

-- This is a select query that will generate a list of SQL commands to execute in batch. 
-- This SQL will generate rows to drop all tables starting with c$. With minor edits
-- you could limit it to a specific database or schema.
select 'drop table ' || TABLE_CATALOG || '.' || TABLE_SCHEMA || '.' || "TABLE_NAME" as SQL_COMMAND
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME like 'c$%';

-- As a convenience, this grabs the last SQL run so that it's easier to insert into 
-- the parameter used to call the stored procedure. 
set query_text = (  select QUERY_TEXT
                    from table(information_schema.query_history(result_limit => 2))
                    where SESSION_ID = Current_Session() and QUERY_TYPE = 'SELECT' order by START_TIME desc);

-- Confirm that the query_text variable has the correct SQL query to generate our SQL commands (grants in this case) to run.
select $query_text;

-- Run the stored procedure. Note that to view its output better, double click on the output to see it in multi-line format,
Call RunBatchSQL($query_text);

--Check the last several queries run to make sure it worked.
select QUERY_TEXT
from table(information_schema.query_history(result_limit => 100))
where SESSION_ID = Current_Session() order by START_TIME desc;

回答2:

The C$ prefixed work tables are a product of ODI use, but they are not created as actual Snowflake temporary tables so they do not benefit from an automatic deletion at JDBC session termination.

The ODI publishers note this about their C$ and I$ work tables:

When a scenario successfully completes, it will automatically delete these tables, as they're transitory and are no longer required. However, where a scenario does not complete successfully, it is possible these tables get left behind and from time to time it maybe desirable to clean up these tables to reclaim space.

For unsuccessful scenarios in your use of ODI that is likely leading to leftover tables on Snowflake, following the link above should help you run a procedure that deletes the leftover work tables (manually or on a schedule). Copying over the relevant procedure here for convenience:

To run the procedure:

Open ODI Studio and connect to the BI Apps ODI Repository.

Navigate to the Designer tab and use the navigator to navigate to: BI Apps Project -> Components -> DW -> Oracle -> Clean Work and Flow Tables folder

In the folder find the Clean Work and Flow Tables package and in this package is the UTILITIES_CLEAN_WORK_AND_FLOW_TABLES scenario.

Right click the scenario and select the 'Execute' option. At the prompt, provide the desired number of days to go back before deleting tables

来源：https://stackoverflow.com/questions/59882865/how-to-drop-temp-tables-created-in-snowflake

标签

database

snowflake-cloud-data-platform