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Simon Griffiths

Thoughts about Technology and Architecture

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Principles

The load-bearing arguments. Slow to change, occasionally rewritten wholesale.

These are the claims the rest of the guide rests on. If one of them is wrong, a lot of what follows is wrong with it.

Copying the data is the easy part The thesis: on a large reporting platform, moving the data is rarely what overruns. Complexity, not volume, decides the method Volume determines how long movement takes; complexity determines whether the approach works at all. Nothing survives twelve hours Long-running migration units fail on first attempt. Design for cheap interruption, not reliable runs. Performance problems are the rule, not the exception We move because the platforms differ, then expect identical behaviour. Results usually match. Performance never does. The numbers will not match, and being right will not save you The better the migration, the more the old and new platforms disagree — and the burden of proof is entirely yours.

Reviewed 25 August 2026

These are my own views, written from years of building and moving large Oracle data platforms. They are not Oracle’s official guidance and this is not Oracle documentation. Volatile product claims are quarantined in Product facts that will date.

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