Change all table priority for unload in short time.

create procedure update_unload_priority() LANGUAGE SQLSCRIPT AS
CURSOR C_TABLE
FOR SELECT 'ALTER TABLE "' || TABLE_NAME || '" UNLOAD PRIORITY 9;' AS SQLTEXT
FROM SYS.TABLES
WHERE SCHEMA_NAME = 'MYSCHEMA' AND TABLE_TYPE = 'COLUMN' and temporary_table_type = 'NONE' AND unload_priority <> 9;
BEGIN
OPEN C_TABLE;
FOR cur_row AS C_TABLE DO
EXEC cur_row.SQLTEXT;
END FOR;
END;

You can convert all row table to column table with below procedure:

create procedure convert_column() LANGUAGE SQLSCRIPT AS
CURSOR C_TABLE
FOR SELECT 'ALTER TABLE "' || TABLE_NAME || '" COLUMN;' AS SQLTEXT
FROM SYS.TABLES
WHERE SCHEMA_NAME = 'SAPABAP1' AND TABLE_TYPE = 'ROW' and temporary_table_type = 'NONE';
BEGIN
OPEN C_TABLE;
FOR cur_row AS C_TABLE DO
EXEC cur_row.SQLTEXT;
END FOR;
END;

You can execute below procedure like this:

CALL convert_column;

You can use below procedure for unloading all column tables in Hana.

create procedure unload_all() LANGUAGE SQLSCRIPT AS
CURSOR C_TABLE
FOR SELECT 'UNLOAD “' || TABLE_NAME || '”;' AS SQLTEXT
FROM SYS.TABLES
WHERE SCHEMA_NAME = 'MYSCHEMA' AND TABLE_TYPE = 'COLUMN' and temporary_table_type = 'NONE';
BEGIN
OPEN C_TABLE;
FOR cur_row AS C_TABLE DO
EXEC cur_row.SQLTEXT;
END FOR;
END;

You call this procedure like below:

CALL unload_all;