Explain Patterns
Browse our collection of common query execution plans to understand how databases process your SQL.
postgresql
PostgreSQL Sequential Scan
Understand how a Sequential Scan works in PostgreSQL and when to optimize it.#postgresql#seq scan#sequential scan
postgresql
PostgreSQL Index Scan
Visualize a standard Index Scan in PostgreSQL execution plans.#postgresql#index scan#btree
mysql
MySQL Simple Select
A basic MySQL execution plan showing a simple table lookup.#mysql#explain#simple
mysql
MySQL Filesort
Understanding the "Using filesort" operation in MySQL queries.#mysql#filesort#sorting
sqlite
SQLite Scan Table
Full table scan in SQLite.#sqlite#scan#table scan
sqlite
SQLite Search Index
Index lookup in SQLite.#sqlite#search#index
postgresql
PostgreSQL Hash Join
Learn how PostgreSQL performs Hash Joins between two tables.#postgresql#hash join#join
postgresql
PostgreSQL CTE (With)
Visualizing Common Table Expressions (WITH clauses) in query plans.#postgresql#cte#with clause
postgresql
PostgreSQL Aggregation
Understanding HashAggregate and GroupAggregate operations.#postgresql#aggregate#group by
postgresql
PostgreSQL Window Function
Execution plan for a query using window functions (OVER clause).#postgresql#window function#rank
postgresql
PostgreSQL Parallel Scan
Parallel sequential scan leveraging multiple CPU cores.#postgresql#parallel#gather
postgresql
PostgreSQL Bitmap Scan
Bitmap Heap Scan combining multiple index results.#postgresql#bitmap scan#index
postgresql
PostgreSQL Merge Join
Merge Join operation on two sorted inputs.#postgresql#merge join#join
postgresql
PostgreSQL Subquery Scan
Scanning a subquery that could not be flattened.#postgresql#subquery#limit
mysql
MySQL Join with Index
An optimized MySQL join using index lookups (ref).#mysql#join#ref
mysql
MySQL UNION
Handling UNION operations with temporary tables.#mysql#union#temporary table
mysql
MySQL Subquery
Correlated subquery execution.#mysql#subquery#performance
mysql
MySQL Covering Index
Query satisfied entirely by the index (Using index).#mysql#covering index#index
mysql
MySQL Derived Table
Querying a subquery in the FROM clause.#mysql#derived table#subquery
mysql
MySQL Full Join (Simulated)
MySQL does not support FULL OUTER JOIN natively.#mysql#full join#union
sqlite
SQLite Covering Index
Covering index scan in SQLite.#sqlite#covering index#performance
sqlite
SQLite Temp B-Tree
Sorting using a temporary B-Tree.#sqlite#sort#temp b-tree
sqlite
SQLite Compound Subquery
Subquery optimization in SQLite.#sqlite#subquery#compound