Analyzing why a table did not appear in the execution plan of a LEFT JOIN query. The root cause is that the optimizer removed the outer table through JOIN elimination optimization when none of its columns were needed in the output.
An in-depth analysis of replica identity's impact on old/new values in PostgreSQL logical replication, detailing data differences for UPDATE/DELETE under default and full modes.
A systematic deep dive into PostgreSQL localization mechanisms, covering locale, collation rules, character set principles, and their impact on query behavior.
Analysis of DELETE throwing 'attempted to delete invisible tuple' while SELECT works fine, tracing through source code to identify VM file corruption as the root cause of the visibility check anomaly
An essay about visiting elderly grandparents in their hometown — observations on daily life in a mining community, elderly dependence on medication, the technology gap, and reflections on intergenerational bonds
Analyzing the counterintuitive phenomenon where a smaller ORDER BY LIMIT value runs slower, caused by the optimizer underestimating the cost of a backward index scan and choosing the wrong index
2023 Year-End Summary: A year of comprehensive PostgreSQL learning, including extracurricular reading rankings, reflections on writing and WeChat official account operations, and thoughts on active learning methodology
Analyzing why an UPDATE became slower after adding partition key filter conditions. The root cause was that partition permission checks caused the optimizer to select the wrong index for all partitions instead of a more selective index.