apps-dba journal

A working journal for Oracle DBAs.

September 27, 2026

Oracle DBA Lesson 22 Part 1 — Startup Stages and File Dependencies

Oracle startup is a sequence of dependencies. Each completed stage tells you what Oracle has successfully established and what informat...

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September 26, 2026

Oracle DBA Lesson 21 Part 5 — Why Dates and Numbers Look Different

A date or number has a value. Displaying it requires text. Two Oracle sessions can apply different conversion rules to the same value a...

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September 26, 2026

Oracle DBA Lesson 21 Part 4 — Why Text Looks Wrong in SQL*Plus

The same database text can look different in two clients. A useful first question is whether the character bytes are being interpreted ...

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September 26, 2026

Oracle DBA Lesson 21 Part 3 — Characters, Bytes, and VARCHAR2 Column Limits

A text value can contain fewer characters than bytes. That difference matters when a column limit is measured in bytes. This lesson sho...

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September 26, 2026

Oracle DBA Lesson 21C — Characters, Bytes, and Text-Column Limits

SQL Developer is another client for the same PDB you already open with SQL*Plus. This lesson connects to LABPDB as COURSE_READER , co...

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Oracle DBA Lesson 106 Part 2 — Operate and hand off a database responsibly

A responsible database administrator connects an observed problem to evidence, chooses a change within the task's scope, verifies i...