What is skip scanning?

Skip scanning is a technique used in database query optimization that involves skipping index entries that do not satisfy certain conditions specified in the query. This can help reduce the number of reads and improve query performance by avoiding unnecessary index lookups.

In skip scanning, the query optimizer leverages multiple indexes on a table to efficiently retrieve the required data. It identifies the most selective index to use first, and then skips over index entries that do not meet the specified conditions, thus reducing the number of index lookups needed to retrieve the data.

Skip scanning can be particularly useful when queries have multiple criteria, each of which is best satisfied by a different index. By skipping unnecessary index entries, skip scanning can significantly reduce the time and resources required to execute the query.

Overall, skip scanning is a useful optimization technique for improving query performance in databases with multiple indexes and complex queries.