2201E

At a glance

Logarithm functions reject zero and negative inputs at their defined-domain guards. Fixed float paths report cannot take logarithm of zero or cannot take logarithm of a negative number; numeric ln and base-log paths apply the same SQLSTATE while handling NaN and infinities separately.

Meaning

2201E is a logarithm domain error, not a generic numeric overflow. In float.c, ln() and log() reject an argument equal to zero and then one less than zero. Numeric ln rejects negative infinity but returns numeric NaN or positive infinity unchanged; numeric base-log rejects a negative or zero base/argument and has defined NaN/infinity results for some positive special-value combinations.

Diagnosis

Read the function signature and the actual numeric type before changing the value. Match the primary message: zero and negative inputs are different guards. For float inputs, NaN does not satisfy either comparison and therefore is not this particular guard; later float overflow or underflow reports are separate conditions. Preserve the input and business rule while checking whether the logarithm domain is really intended.

Response

Supply a value in the domain required by the named logarithm function, or change the business rule explicitly. If an ERROR occurred inside an explicit transaction, roll back or roll back to the existing savepoint before retrying; an autocommit client can retry the corrected statement. Casting blindly can move the value without making the operation defined.

Versions

The locked catalogue records this condition from 8.0.0; the fixed source paths here are PostgreSQL 18.6. No natural runtime observation is claimed for this page.

Related

22003, 22012

Sources

Fixed paths include src/backend/utils/adt/float.c#L1687-1747 and src/backend/utils/adt/numeric.c#L3935-4020 plus #L11156-11168, which bind the zero/negative guards and special-value branches. The structured evidence record retains the exact message roles and scope boundary; no natural runtime was run.

Source evidence

Evidence belongs to the frozen source and runtime versions listed here. It is not a runtime verification of the selected manual version.

• src/backend/utils/errcodes.txt · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• src/backend/utils/adt/float.c · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• src/backend/utils/adt/numeric.c · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• src/backend/utils/adt/numeric.c · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7

Message templates

cannot take logarithm of zero

cannot take logarithm of a negative number

Reproduction & repair cases

No reproduction case is attached to this condition.

Recorded runtime evidence

No runtime observation is attached to this entry.