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Aikesheng Open Source Community

Nov 5, 2024 · Databases

Using WM_CONCAT in OceanBase 3.x: Restoring Order with NO_REWRITE Hint

This article explains how to replace Oracle's XMLAGG with OceanBase's WM_CONCAT, analyzes why the result order is lost in OceanBase 3.x, demonstrates reproduction steps, shows that adding a NO_REWRITE hint restores ordering, and provides the final SQL solution and notes for OceanBase 4.x.

HintOceanBaseSQL

0 likes · 9 min read

Using WM_CONCAT in OceanBase 3.x: Restoring Order with NO_REWRITE Hint

Aikesheng Open Source Community

Nov 27, 2020 · Databases

Analyzing MySQL 5.7 Optimizer Trace: Why a Suboptimal Execution Plan Occurs and How to Use Hints

This article examines a slow MySQL 5.7 query, uses the optimizer trace tool to reveal why the optimizer chose an inefficient plan, explains the role of fan‑out estimation on information_schema tables, and shows how hints can be applied to correct the plan.

HintINFORMATION_SCHEMAMySQL

0 likes · 5 min read

Analyzing MySQL 5.7 Optimizer Trace: Why a Suboptimal Execution Plan Occurs and How to Use Hints

Aikesheng Open Source Community

Dec 23, 2019 · Databases

Using Hints in DBLE to Control Routing and Execute Custom SQL

This article explains how DBLE's hint mechanism can be used to specify database routing, classify different hint types, and demonstrate practical operations such as invoking stored procedures and executing custom SQL statements on selected nodes.

DBLEHintSQL

0 likes · 5 min read

Using Hints in DBLE to Control Routing and Execute Custom SQL