This article explains how MySQL executes ORDER BY queries, the role of sort_buffer, the difference between full-field and rowid sorting, how parameters like sort_buffer_size and max_length_for_sort_data affect performance, and how proper indexing can eliminate the need for sorting altogether.
This article explains how MySQL executes ORDER BY queries, compares the default sorting algorithm with the rowid method, and provides practical optimization steps such as indexing, adjusting sort_buffer settings, and choosing the appropriate algorithm based on data size and memory.
This article explains the internal execution process of MySQL's ORDER BY, compares full‑field and rowid sorting, shows how indexes, sort_buffer size and max_length_for_sort_data affect performance, and provides practical optimization techniques such as composite and covering indexes.
This article details a real‑world migration from Oracle 11g on IBM AIX to Oracle 19c, focusing on exporting a 2 TB LOB‑heavy table by adjusting undo retention, then using ROWID‑based modulo queries with Data Pump to achieve balanced, error‑free parallel exports.
This article explores MySQL's hidden rowid concept, demonstrates how to observe its existence, explains its relationship with primary keys, highlights the risks of primary‑key misuse, and provides a step‑by‑step test that reveals rowid's potential overflow bottleneck.
This article explains how Oracle's logical structures—blocks, segments, tablespaces, and rowids—affect SQL performance, presents detailed experiments on block capacity, row migration, segment handling, tablespace behavior, and provides practical optimization guidelines based on observed logical read reductions.
This guide explains how to locate rows with identical values across one or several columns using self‑joins, GROUP BY, DISTINCT, and rowid, and provides step‑by‑step SQL statements to safely delete the extra duplicate entries from a table.
