Which data types are appropriate for storing lat/lon in the database, and why?

Which data types are appropriate for storing lat/lon in the database, and why?

• A. DECIMAL(9,6) or DECIMAL(10,7) for precision; FLOAT/DOUBLE may cause rounding errors
• B. VARCHAR(20)
• C. TEXT
• D. INTEGER

Answer: (A)

Storing latitudes and longitudes with fixed-point decimals gives you exact, predictable values for numeric operations and indexing. DECIMAL lets you specify both precision and scale, so coordinates remain exact as entered instead of being approximated by binary representations. For geographic coordinates you want enough fractional digits to represent places accurately, but not so many that you waste space. DECIMAL(9,6) and DECIMAL(10,7) provide ample room: three digits before the decimal and six or seven after, which covers the ranges of latitude (-90 to 90) and longitude (-180 to 180). The precision of 1e-6 degree (or even 1e-7 with the larger scale) yields practical sub-meter accuracy in many cases. Floating-point types like FLOAT or DOUBLE store numbers in binary, which can introduce tiny rounding differences. Those small discrepancies can cause tricky issues in equality checks, bounding box queries, or joins. Textual types such as VARCHAR or TEXT store data as characters, making numeric calculations and indexing inefficient and error-prone. An INTEGER would discard the fractional part, losing essential precision needed for coordinates. So, using precise fixed-point decimals, such as DECIMAL(9,6) or DECIMAL(10,7), is the best approach among the options for storing lat/lon.

Storing latitudes and longitudes with fixed-point decimals gives you exact, predictable values for numeric operations and indexing. DECIMAL lets you specify both precision and scale, so coordinates remain exact as entered instead of being approximated by binary representations. For geographic coordinates you want enough fractional digits to represent places accurately, but not so many that you waste space. DECIMAL(9,6) and DECIMAL(10,7) provide ample room: three digits before the decimal and six or seven after, which covers the ranges of latitude (-90 to 90) and longitude (-180 to 180). The precision of 1e-6 degree (or even 1e-7 with the larger scale) yields practical sub-meter accuracy in many cases.

Floating-point types like FLOAT or DOUBLE store numbers in binary, which can introduce tiny rounding differences. Those small discrepancies can cause tricky issues in equality checks, bounding box queries, or joins. Textual types such as VARCHAR or TEXT store data as characters, making numeric calculations and indexing inefficient and error-prone. An INTEGER would discard the fractional part, losing essential precision needed for coordinates.

So, using precise fixed-point decimals, such as DECIMAL(9,6) or DECIMAL(10,7), is the best approach among the options for storing lat/lon.