How does Oracle SQL query work internally?

How does SQL query work internally?

SQL Query mainly works in three phases .11) Row filtering - Phase 1: Row filtering - phase 1 are done by FROM, WHERE , GROUP BY , HAVING clause.22) Column filtering: Columns are filtered by SELECT clause.33) Row filtering - Phase 2: Row filtering - phase 2 are done by DISTINCT , ORDER BY , LIMIT clause.how does a SQL query work? - Stack Overflow

How does Oracle SELECT query work?

Every SQL query you send to a server has to go through three (four – in case of SELECT) stages. First of all, Oracle will search for a matching SQL hash in Library Cache. If the hash is found it will just retrieve the associated explain plan and executes it.

How does an SQL query execute?

SQL's from clause selects and joins your tables and is the first executed part of a query. This means that in queries with joins, the join is the first thing to happen. It's a good practice to limit or pre-aggregate tables before potentially large joins, which can otherwise be very memory intensive.

What happens when a query is executed in Oracle?

Execute Phase - During the execute phase, Oracle executes the statement, reports any possible errors, and if everything is as it should be, forms the result set. Unless the SQL statement being executed is a query, this is the last step of the execution.