This article analyzes JD's self‑developed database kernel DongSQL, describing its architecture, the challenges of overload, flash‑sale write spikes, cache consistency, execution‑plan drift, and thread congestion, and explains how hint‑based limiting, RETURNING syntax, statement outlines, and a built‑in thread pool address each issue.
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.
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.
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.
