JoongHyuk Shin

Database engine developer. Writing about PostgreSQL internals, from source code to what it means for your application.

Seoul, Korea Joined on May 4, 2026 sjh910805@gmail.com

JoongHyuk Shin

Jun 21

Closing Chapter 1: From Query to Data

#postgres #database #internals #query

2 min read

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JoongHyuk Shin

Jun 21

1.5.5 Parallel Query: How Worker Processes Cooperate

#postgres #database #internals #executor

8 min read

JoongHyuk Shin

Jun 21

1.5.4 Aggregation: HashAgg, GroupAgg, Sort-Based

#postgres #database #internals #executor

7 min read

JoongHyuk Shin

Jun 21

1.5.3 Join Nodes: NestLoop, HashJoin, MergeJoin

#postgres #database #internals #executor

9 min read

JoongHyuk Shin

Jun 21

1.5.2 Scan Nodes: SeqScan, IndexScan, BitmapScan

#postgres #database #internals #executor

8 min read

JoongHyuk Shin

Jun 21

1.5.1 The Volcano Iterator Model

#postgres #database #internals #executor

8 min read

JoongHyuk Shin

Jun 21

1.5 Executor: How Results Come Back

#postgres #database #internals #executor

4 min read

JoongHyuk Shin

Jun 21

1.4.10 Planner Hook: When It Fires, How to Use It

#postgres #database #internals #planner

9 min read

JoongHyuk Shin

Jun 21

1.4.9 Planner Preprocessing: Subquery Pull-up, Predicate Pushdown, Equivalence Classes

#postgres #database #internals #planner

12 min read

JoongHyuk Shin

Jun 21

1.4.8 Statistics: pg_statistic and Selectivity

#postgres #database #internals #planner

12 min read

JoongHyuk Shin

Jun 21

1.4.7 Parallel Cost: When to Go Parallel and How Many Workers

#postgres #database #internals #planner

8 min read

JoongHyuk Shin

Jun 21

1.4.6 Aggregate Cost: Choosing HashAgg vs GroupAgg

#postgres #database #internals #planner

9 min read

JoongHyuk Shin

Jun 21

1.4.5 Join Order: Dynamic Programming vs GEQO

#postgres #database #internals #planner

12 min read

JoongHyuk Shin

Jun 21

1.4.4 Join Strategies: Nested Loop, Hash, Merge

#postgres #database #internals #planner

12 min read

JoongHyuk Shin

Jun 4

1.4.3 Cost Model: The Index Scan Formula

#postgres #database #internals #planner

13 min read

JoongHyuk Shin

Jun 3

1.4.2 Cost Model: Sequential Scan Formula

#postgres #database #internals #planner

10 min read

JoongHyuk Shin

Jun 2

1.4.1 Path Tree vs Plan Tree: What's the Difference

#postgres #database #internals #planner

11 min read

JoongHyuk Shin

May 29

1.4 Planner: Which Path to Take

#postgres #database #internals #planner

4 min read

JoongHyuk Shin

May 25

1.3.4 RETURNING Mapping and View-Target DML Transformation

#postgres #database #internals #query

9 min read

JoongHyuk Shin

May 22

1.3.3 INSERT/UPDATE/DELETE Targetlist Normalization (Default Expansion)

#postgres #database #internals #query

11 min read

JoongHyuk Shin

May 17

1.3.2 How RLS Rewrites Queries (Mechanism)

#postgres #database #internals #query

10 min read

JoongHyuk Shin

May 14

1.3.1 Rule System and View Expansion

#postgres #database #internals #query

10 min read

JoongHyuk Shin

May 14

1.3 Rewriter: How a Query Is Rewritten

#postgres #database #internals #query

2 min read

JoongHyuk Shin

May 10

1.2.3 Query Tree Node Types: Query, RangeTblEntry, TargetEntry

#postgres #database #internals #query

7 min read

JoongHyuk Shin

May 7

1.2.2 Semantic Analysis: Name Resolution, Type Checking, Catalog Lookup

#postgres #database #internals #query

9 min read

JoongHyuk Shin

May 6

1.2.1 From SQL Text to Raw Parse Tree

#postgres #database #internals #query

10 min read

JoongHyuk Shin

May 6

1.2 Parser and Analyzer: How SQL Gets Its Meaning

#postgres #database #internals #query

2 min read

JoongHyuk Shin

May 5

1.1.3 The optimizable vs utility fork

#postgres #database #internals #query

6 min read

JoongHyuk Shin

May 5

1.1.2 Simple vs Extended

#postgres #database #internals #query

7 min read

JoongHyuk Shin

May 4

1.1.1 Life of a Query

#postgres #database #internals #query

5 min read

JoongHyuk Shin

May 4

1.1 Where Does a Query Go?

#postgres #database #internals #query

1 min read