1. What is the Oracle NUMBER data type?

The NUMBER data type is used to store fixed and floating-point numbers. It allows both precision and scale to be defined and supports very large or very small numbers.

 

2. What is the syntax of the NUMBER data type?

NUMBER(p, s)

·        p (precision): total number of digits (1 to 38).

·        s (scale): number of digits to the right of the decimal point (–84 to 127).

Examples:

·        NUMBER(5,2) can store numbers like 123.45.

·        NUMBER(3) can store integers up to 999.

 

3. What happens if you omit precision and scale in NUMBER?

If you define a column as just NUMBER, Oracle allows any number of digits up to the max (38 digits of precision) and the decimal point can be anywhere.

salary NUMBER; -- Max flexibility, but can impact performance

 

4. What is the maximum and minimum value a NUMBER can store?

·        Maximum: 9.999...E125 (38 9s)

·        Minimum (non-zero): 1.0E-130

·        Based on NUMBER(p,s), limits vary with the defined p and s.

 

5. What is the difference between NUMBER, NUMBER(p), and NUMBER(p,s)?

·        NUMBER – Unlimited digits and scale (up to limits).

·        NUMBER(p) – Fixed precision; whole numbers only.

·        NUMBER(p,s) – Fixed precision and scale; used for exact numeric values like currency.

 

6. Does NUMBER affect performance in real-time systems?

Yes. Using unbounded NUMBER (i.e., without precision/scale) can cause slower performance due to internal conversions. Always define precision and scale when possible to optimize storage and performance.

 

7. Is NUMBER a fixed-precision or floating-point type?

It can act as both:

·        Fixed-point when precision and scale are defined.

·        Floating-point when used without limits.

 

8. What happens if a value exceeds the defined precision?

Oracle will raise a ORA-01438: value larger than specified precision allowed error during an INSERT or UPDATE.

 

9. How does Oracle internally store NUMBER?

Oracle stores numbers in a variable-length binary format, not ASCII or raw decimal. This allows efficient use of storage but requires internal conversion.

 

10. What are common use cases for different NUMBER types?

·        NUMBER(5,2) – Currency (e.g., 999.99)

·        NUMBER(10,0) – Account IDs, whole numbers

·        NUMBER – Temporary or dynamic numeric values

 

11. Can you use NUMBER for identity columns (auto-increment)?

Yes, in Oracle 12c+:

id NUMBER GENERATED BY DEFAULT AS IDENTITY

 

12. How does NUMBER compare to FLOAT or BINARY_FLOAT?

·        NUMBER – Exact arithmetic, slower for scientific calculations.

·        BINARY_FLOAT/DOUBLE – Faster for approximate values, but may lose precision.

Use NUMBER when accuracy is critical (e.g., money), and BINARY_FLOAT when speed matters more (e.g., real-time telemetry).

 

13. How does Oracle handle rounding and truncation with NUMBER?

If a value has more decimal places than allowed by scale:

·        It is rounded unless explicitly truncated.

ROUND(123.456, 2) → 123.46

TRUNC(123.456, 2) → 123.45

 

14. What happens in real-time inserts if a value violates the NUMBER constraints?

·        Oracle throws an error, and the entire DML operation is rolled back.

·        In high-volume inserts, these errors can severely affect throughput.

 

15. How can I avoid precision issues in real-time ETL jobs?

·        Use NUMBER(p,s) explicitly.

·        Validate input ranges before inserting.

·        Use staging tables to catch bad data before loading into production tables.

 

16. How do NUMBER fields affect indexing performance?

Indexing on NUMBER(p,0) is efficient. Indexing floating or undefined precision NUMBER columns can increase index size and reduce performance.

 

17. Can a NUMBER column be used in partitioning or hashing?

Yes. Especially NUMBER(10,0) is common in:

PARTITION BY HASH(account_id)

Avoid high-precision floating-point numbers for partition keys.

 

18. Is NUMBER suitable for time-series or telemetry data?

Partially. For telemetry (high-frequency data), prefer BINARY_FLOAT or BINARY_DOUBLE for performance, unless exact values are critical.

 

19. How does Oracle handle arithmetic between different NUMBER precisions?

Oracle promotes numbers to the higher precision and scale during operations, which can cause overflow or truncation errors if not handled properly.

 

20. What are best practices for using NUMBER in real-time applications?

·        Always define precision and scale.

·        Avoid NUMBER without precision in OLTP systems.

·        Use numeric constraints (CHECK) to enforce valid ranges.

·        Use bind variables to reduce parsing and improve performance.

·        Use appropriate data types: don’t use NUMBER when INTEGER or BINARY_FLOAT is better suited.

 

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