Table scans occur when a query scans an entire table instead of using an index. Except for small tables, table scans can lead to very slow queries and poor database performance.
Adding any missing indexes for the query that's causing table scans should improve query times.
If table scans are detected for tables with more than 10,000 rows, a recommendation will be created for that table. Investigate the slowest queries and slowest IO queries for the affected table to understand which indexes are missing.
EXPLAIN plans may also be useful in understanding which indexes are missing.
Add any missing indexes or ignore the recommendation to remove it from your recommendation dashboard.