Partition pruning behavior in PostgreSQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is partition pruning in PostgreSQL?

Partition pruning is a technique where PostgreSQL skips scanning partitions that cannot contain any matching rows for a query, improving query performance.

intermediate

When does PostgreSQL perform partition pruning?

PostgreSQL performs partition pruning during query planning and execution phases to avoid scanning irrelevant partitions based on query conditions.

intermediate

What types of partition pruning does PostgreSQL support?

PostgreSQL supports static pruning (at plan time) and dynamic pruning (at execution time) to exclude partitions based on query parameters.

advanced

How does dynamic partition pruning differ from static pruning?

Static pruning happens during query planning using constant values, while dynamic pruning happens during execution using parameter values or runtime information.

beginner

Why is partition pruning important for large partitioned tables?

Partition pruning reduces the amount of data scanned by skipping irrelevant partitions, which speeds up queries and reduces resource usage on large partitioned tables.

What does partition pruning help improve in PostgreSQL?

A Query performance by skipping irrelevant partitions

B Data insertion speed

C Backup compression

D Index creation time

Partition pruning improves query performance by avoiding scanning partitions that cannot contain matching rows.

When does static partition pruning occur?

A During query planning

B During query execution

C During data insertion

D During index creation

Static pruning happens during query planning using constant query values.

Dynamic partition pruning uses which of the following to prune partitions?

A Constant values only

B Index metadata

C Table statistics only

D Runtime parameters or execution-time info

Dynamic pruning uses runtime parameters or execution-time information to prune partitions.

Which PostgreSQL feature helps reduce scanned data on large partitioned tables?

A Replication

B Partition pruning

C Vacuuming

D Triggers

Partition pruning reduces scanned data by skipping irrelevant partitions.

Partition pruning is most effective when queries include conditions on:

A Random columns

B Non-indexed columns

C Partition key columns

D System columns

Pruning works best when queries filter on partition key columns.

Explain how partition pruning works in PostgreSQL and why it improves query performance.

Think about how skipping parts of data helps queries run faster.

Describe the difference between static and dynamic partition pruning in PostgreSQL.

Consider when the pruning decision happens and what information it uses.