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cost-based optimizer

13 articles · Page 1 of 1
Programmer XiaoFu
Programmer XiaoFu
Jun 1, 2026 · Databases

Why Does an OR Between Two Indexed Columns Still Trigger a Full Table Scan?

Even though the phone and email columns each have a single‑column index, an OR condition forces MySQL's cost‑based optimizer to choose a full table scan because the estimated cost of index merge (random I/O and possible sort‑union) exceeds the cost of a sequential scan, and the article explains the underlying mechanics and practical workarounds.

OR queryQuery OptimizationSQL
0 likes · 10 min read
Why Does an OR Between Two Indexed Columns Still Trigger a Full Table Scan?
Past Memory Big Data
Past Memory Big Data
Apr 19, 2024 · Databases

How ByteHouse Achieves Hundred‑Fold OLAP Performance Gains

ByteHouse, a cloud‑native data warehouse built on ClickHouse, redesigns storage‑compute separation, introduces a new MPP architecture, rule‑based and cost‑based optimizers, exchange runtime filters, and parallelism techniques, delivering 10‑200× faster query performance on TPC‑DS, TPC‑H and SSB benchmarks and boosting point‑lookup QPS to 32,000.

ByteHouseData WarehouseOLAP
0 likes · 19 min read
How ByteHouse Achieves Hundred‑Fold OLAP Performance Gains
ITPUB
ITPUB
Aug 11, 2023 · Databases

Can PostgreSQL Replace Oracle in Enterprise Core Systems? Key Gaps and Challenges

The article examines why PostgreSQL still falls short of being a core enterprise database by analyzing eight technical gaps—such as XID64 support, LWLOCK efficiency, shared buffer performance, recovery, high availability, zero data loss, resource management, and CBO optimizer maturity—while reflecting on industry trends and Oracle's dominance.

Database PerformanceEnterprise DatabasesOracle Comparison
0 likes · 10 min read
Can PostgreSQL Replace Oracle in Enterprise Core Systems? Key Gaps and Challenges
dbaplus Community
dbaplus Community
May 10, 2022 · Databases

How Meituan Optimizes MySQL Slow Queries with Cost‑Based Index Recommendations

This article explains how Meituan tackles MySQL slow‑query problems by leveraging the database cost‑based optimizer to generate index suggestions, evaluate their quality, and operate a full‑stack governance workflow that includes data collection, statistical modeling, validation, and continuous improvement.

Database PerformanceIndex RecommendationSlow Query
0 likes · 23 min read
How Meituan Optimizes MySQL Slow Queries with Cost‑Based Index Recommendations
ITPUB
ITPUB
Mar 7, 2022 · Databases

Why Oracle’s Hidden Predicate Pushdown Alters SQL Plans – Lessons for Domestic Databases

The article examines Oracle’s unexpected predicate‑pushdown rewrite observed in trace files, shows how it alters execution plans through a virtual column index, and draws lessons for Chinese database vendors on product depth, architecture design, and after‑sales support to close the gap with global leaders.

Domestic databasesOraclePredicate Pushdown
0 likes · 8 min read
Why Oracle’s Hidden Predicate Pushdown Alters SQL Plans – Lessons for Domestic Databases
Aikesheng Open Source Community
Aikesheng Open Source Community
Sep 26, 2021 · Databases

Why MySQL Optimizer Chooses Full Table Scan Over Index Scan: Cost Analysis and Experiment

This article explains how MySQL's cost‑based optimizer decides between using an index and performing a full table scan, demonstrates the behavior with a large test table, shows optimizer trace details, and clarifies why index access can sometimes be more expensive than scanning the whole table.

Full Table ScanQuery Optimizationcost-based optimizer
0 likes · 8 min read
Why MySQL Optimizer Chooses Full Table Scan Over Index Scan: Cost Analysis and Experiment
MaGe Linux Operations
MaGe Linux Operations
Dec 1, 2019 · Databases

Unlock MySQL Performance: Deep Dive into Query Optimization & Index Design

This article explains MySQL's logical architecture, query execution steps, client‑server protocol, query cache behavior, cost‑based optimizer mechanics, and practical index design strategies—including B+Tree fundamentals, covering indexes, and common pitfalls—to help developers achieve measurable performance improvements.

Database PerformanceQuery Optimizationcost-based optimizer
0 likes · 32 min read
Unlock MySQL Performance: Deep Dive into Query Optimization & Index Design
Aikesheng Open Source Community
Aikesheng Open Source Community
Sep 3, 2019 · Databases

Cost‑Based MySQL Query Optimization: Concepts, Tools, and Practical Tips

This article summarizes a MySQL webinar covering cost‑based query optimization, monitoring and analysis tools, data‑access methods and index selection, join optimization techniques, and ways to influence the optimizer through hints and configuration, providing a concise technical reference for database practitioners.

Index SelectionOptimizer HintsPerformance Schema
0 likes · 11 min read
Cost‑Based MySQL Query Optimization: Concepts, Tools, and Practical Tips
360 Tech Engineering
360 Tech Engineering
Jan 7, 2019 · Databases

SQL Query Analysis and Access Path Strategies

This article explains how relational optimizers validate, analyze, and transform SQL statements into executable code, detailing the four-step optimization process, query‑analysis factors, cost‑based access‑path selection, table scans, index lookups, and the role of data prefetching in improving performance.

Access PathDatabase PerformanceIndex Scan
0 likes · 12 min read
SQL Query Analysis and Access Path Strategies
StarRing Big Data Open Lab
StarRing Big Data Open Lab
Jan 20, 2017 · Databases

Resolving Common CBO Issues and Optimizing Inceptor Queries

This article examines typical problems encountered when using Cost‑Based Optimizer (CBO) in Inceptor, offers step‑by‑step troubleshooting methods, and demonstrates a real‑world case where statistical information is collected with Preanalyze, CBO is enabled, and query plans are refined for large‑scale JOIN operations.

CBOInceptorPreanalyze
0 likes · 11 min read
Resolving Common CBO Issues and Optimizing Inceptor Queries
ITPUB
ITPUB
Sep 12, 2016 · Databases

Why Oracle’s Optimizer Misestimates Multi‑Column Filters and How to Fix It

This article explains how Oracle’s Cost‑Based Optimizer can produce incorrect row estimates for queries with multiple column predicates, demonstrates the problem with a test table, and shows that gathering multi‑column statistics resolves the misestimation, improving execution plans.

Execution PlanMulti-Column StatisticsOracle
0 likes · 8 min read
Why Oracle’s Optimizer Misestimates Multi‑Column Filters and How to Fix It