← Databases
Copying is the easy part; the verification afterwards decides whether a migration succeeded. Compare record counts, data types, dates and accented characters between source and target, and record that comparison. Without that evidence nobody knows whether everything came across.
Where it goes wrong
- Dates
- Platforms have different ranges and notations. A date in 1899 or 9999 is usually an empty value that was not translated properly.
- Accented characters
- Old files often sit in a DOS code page. Without conversion, accents and punctuation become unreadable.
- Numbers and rounding
- An amount transferred as a floating point value drifts cent by cent. Use an exact type.
- Empty values
- The difference between empty, zero and "not filled in" is easily lost, producing wrong totals.
How to verify it
- Count everything
- Record counts per table, in source and target. The simplest check and also the most effective.
- Compare totals
- Sum amounts and quantities per period. A difference means a conversion error.
- Sample the edges
- The oldest and newest records, the longest texts, the unusual characters. That is where the trouble hides.
- Run both
- Let old and new run side by side for a while and compare the outcomes before you switch off.
We supply that comparison as standard, so it is demonstrable that everything came across complete and correct.
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