The search optimization service in Snowflake is designed to improve the performance of selective point lookup queries on large tables, which is ideal for scenarios where a query returns a small amount of data from a very large base table1. References: [COF-C02] SnowPro Core Certification Exam Study Guide

In Snowflake, reader accounts are special types of accounts that allow data sharing with external consumers without them having their own Snowflake account. The creation and management of reader accounts can be performed by users with the ACCOUNTADMIN role or the ORGADMIN role. The ACCOUNTADMIN role has comprehensive administrative privileges within a Snowflake account, including managing other accounts and roles. The ORGADMIN role, which is higher in hierarchy, oversees multiple accounts within an organization and can manage reader accounts across those accounts.
Snowflake Documentation: Creating and Managing Reader Accounts