You can use the preview feature to debug data transformation scripts. This feature supports the Quick preview mode and Advanced preview mode. This topic describes the two preview modes.
Quick preview mode
In Quick preview mode, you can check whether the syntax of a data transformation script is valid and whether data is efficiently transformed as expected. You can also use the raw logs of a Logstore or custom data as test data. You can perform the preceding operations in Quick preview mode free of charge. For more information, see Quick preview.
In Quick preview mode, Log Service cannot access the actual data that is specified by resource functions. The resource functions include res_local, res_rds_mysql, res_log_logstore_pull, and res_oss_file. If you use a resource function in a data transformation rule, you can enter test data on the Dimension Table tab to preview the data.
Advanced preview mode
In Advanced preview mode, Log Service accesses the specified Logstore and reads data from the Logstore to test the data and simulate the data transformation process. In Advanced preview mode, the specified transformation rule must be granted the required permissions to read data. The transformation speed in Advanced preview mode is slower than the transformation speed in Quick preview mode. You are charged for the traffic that is generated during the preview process. The traffic fee is included in the data transformation fee.
We recommend that you use the Quick preview mode to check whether the data is transformed as expected and the Advanced preview mode to check whether a resource function is configured as required. For more information, see Advanced preview.