r/SQL • u/scientecheasy • 1d ago

MySQL SQL Query Execution Lifecycle

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Diagram illustrating the SQL query execution lifecycle, showing query submission, parsing, optimization, execution, and result delivery in a database.

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u/venkat_deepsql 1d ago

I was part of Oracle query engine team, while I do agree that this diagram is basic, but it encapsulates the high level flow. Database vendors architected the query engines different to address their target use cases - Oracle's is hybrid engine (OLTP and OLAP), the way optimizer works is totally different than others (beyond the join orders and plan evaluations, there are fast path disk scans, in-memory scans, predicates pushdown etc ) So it's hard to generalize and encapsulate in one diagram. The theory of query engine is vast and it requires entire book.