The error occurs when a logarithm function receives zero or a negative number, which is mathematically undefined in PostgreSQL.
PostgreSQL Error 2201E – invalid_argument_for_logarithm – appears when LOG(), LN(), or related math functions receive zero or negative input. Pass a positive numeric value or wrap the call with NULLIF/CASE to guard bad data to resolve the issue.
PostgreSQL Error 2201E
PostgreSQL raises SQLSTATE 2201E when a logarithm function such as LN(), LOG(), or LOG10() receives an argument that is not strictly greater than zero. Because the natural and common logarithms are undefined for zero and negative numbers, the engine aborts the statement.
The error prevents silent mathematical mistakes that could propagate downstream calculations. Fixing it quickly protects data quality and application stability.
Zero or negative values supplied directly in a query trigger the exception immediately.
Dynamic inputs from tables, parameters, or user forms that evaluate to non-positive numbers also raise SQLSTATE 2201E during execution.
Type mismatches that coerce text to numeric can yield a default 0, inadvertently causing the logarithm to fail. Rounding issues in floating-point math may push tiny positives to exactly 0.
Validate that every input to LN(), LOG(), or LOG10() is greater than 0. Filter, transform, or substitute unsafe values before calling the function.
Use WHERE clauses, CASE expressions, or NULLIF to bypass bad rows.
When data cleansing is impractical, wrap the logarithm in CASE to return NULL or a fallback number for invalid inputs, allowing the query to finish without an exception.
Analytics queries on clickstream tables often hit the error when counts are 0.
Add WHERE count>0 or CASE WHEN count>0 THEN LN(count) END.
ETL jobs dividing two integers can create 0.000… results that round to 0; casting to numeric with higher precision preserves the small positive value and avoids the error.
Store only positive values when business rules demand logarithms later. Enforce CHECK (value>0) constraints on columns used in log math.
Add unit tests for SQL functions that compute logarithms, ensuring they handle edge cases.
Monitor application logs and dashboards for spikes in SQLSTATE 2201E to detect data anomalies early.
Division by zero (SQLSTATE 22012) arises in similar numeric edge cases; validate denominators. Numeric value out of range (SQLSTATE 22003) occurs when results overflow data types; widen types or clamp values.
Cannot take square root of a negative number (SQLSTATE 2201F) is analogous; apply ABS() or CASE to guarantee non-negative input.
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Yes. LN(NULL) returns NULL and does not raise SQLSTATE 2201E.
No. PostgreSQL enforces numeric domain rules. You must sanitize inputs.
All supported versions (9.x to 16) enforce this check for LN/LOG/LOG10.
Galaxy autocomplete warns on unsafe literals and its AI copilot suggests CASE guards, reducing the chance of invalid arguments reaching math functions.
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