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⚡ AI Lessons
Dev.to · JoongHyuk Shin
⚡ AI Lesson
1mo ago
Closing Chapter 1: From Query to Data
We opened Chapter 1 with a single line, SELECT * FROM users WHERE id = 1. For that line to leave the...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
1mo ago
1.5 Executor: How Results Come Back
By the time 1.4 ends, the planner has produced one PlannedStmt. Inside it is an execution tree built...
Dev.to · JoongHyuk Shin
🔧 Backend Engineering
⚡ AI Lesson
1mo ago
1.4.10 Planner Hook: When It Fires, How to Use It
Everything from 1.4.1 through 1.4.9 happened inside a single function, standard_planner(). Building...
Dev.to · JoongHyuk Shin
📐 ML Fundamentals
⚡ AI Lesson
1mo ago
1.4.9 Planner Preprocessing: Subquery Pull-up, Predicate Pushdown, Equivalence Classes
So far we have seen the planner build candidate paths and rank them by cost, choose join methods and...
Dev.to · JoongHyuk Shin
📊 Data Analytics & Business Intelligence
⚡ AI Lesson
1mo ago
1.4.6 Aggregate Cost: Choosing HashAgg vs GroupAgg
A query like SELECT region, COUNT(*) FROM sales GROUP BY region folds many rows together, collapsing...
Dev.to · JoongHyuk Shin
📊 Data Analytics & Business Intelligence
⚡ AI Lesson
1mo ago
1.4.4 Join Strategies: Nested Loop, Hash, Merge
The costs in 1.4.2 and 1.4.3 were about how to read a single table. A join combines two tables, and...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.3.4 RETURNING Mapping and View-Target DML Transformation
The previous section (1.3.3) looked at the work the rewriter does to fill empty slots with values and...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.3.3 INSERT/UPDATE/DELETE Targetlist Normalization (Default Expansion)
The two rewriter tasks we have seen so far, view expansion and RLS policy injection, were unpacked...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.3.2 How RLS Rewrites Queries (Mechanism)
Once you put row-level security (RLS) on a table, queries that read from that table don't run the way...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.3.1 Rule system and view expansion
This section is about how PostgreSQL makes a view reference disappear. When a user writes SELECT *...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.3 Rewriter: How a Query is Rewritten
By the time the analysis stage from 1.2 finishes, the SQL has become a Query tree. Catalog...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.2.3 Query tree node types: Query, RangeTblEntry, TargetEntry
After the Analyze stage from 1.2.2, the raw parse tree has become a Query tree. This section is about...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.2 Parser and Analyzer: How SQL Gets Its Meaning
A line like SELECT name FROM users WHERE id = 1 is just text when the client sends it. The first...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.1.3 Optimizable vs Utility
Inside the five-stage pipeline from 1.1.1, there is another fork right after the parser. PostgreSQL...
Dev.to · JoongHyuk Shin
⚡ AI Lesson
2mo ago
1.1.2 Simple vs Extended
The fork visible in 1.1.1 — simple query protocol on one side, extended on the other — is the subject...
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