How to quickly find data when Oracle data volume is large

Query the Eai_salesorder table for today (20180712) data.

Method One

SELECT * from Eai_salesorder where eaicreatedate like ' 2018-07-12% '; spents 20.176 seconds

Method Two

SELECT * FROM (SELECT * to Eai_salesorder ORDER BY eaicreatedate Desc) where rownum< ' "ORDER by rownum Desc; spents 32.628 seconds

It has long been thought that Oracle queries are time-consuming, so when there is this query requirement, there is no way to query with method one. Colleague's proposal, unexpectedly 20 seconds to find out, need to further understand the query mechanism ...

How to quickly find data when Oracle data volume is large