Pattern based discovery fails with the following error:

yyyy-mm-dd hh:mm:ss: The number of rows in the table has reached the maximum limit of 20,000. To adjust this use the glide property com.glide.closure_max_rows_per_table.

Probable Cause:

This indicates that the amount of data collected in the table variable is huge and is exceeding the default number of rows per table.

Resolution:

This is a MID server property "ecc_agent_property" and not a system property "sys_property". Therefore, you will need to add it as follows:

1. Open this form to add a new property in "ecc_agent_property" table: 
   https://<instance_name>.service-now.com/ecc_agent_property.do
   name: com.glide.closure_max_rows_per_table
   value: 100000 (there isn't a definite figure for the value. You can try increasing it gradually until the error is not seen anymore)
   mid server: leave empty, if you want it to apply to all MID servers.
   
   
2. Restart the specific MID server used in the discovery.