prestodb/presto · error · PrestoException

INVALID_FUNCTION_ARGUMENT

INVALID_FUNCTION_ARGUMENT

Error message

Key-value delimiter must appear exactly once in each entry. Bad input:

What it means

split_to_multimap (like split_to_map but producing a multimap) requires each entry to contain the key-value delimiter at least once. When indexOf(keyValueDelimiter) < 0 for a pair, the entry cannot be decomposed into key and value, so INVALID_FUNCTION_ARGUMENT is thrown with the bad pair.

Source

Thrown at presto-main-base/src/main/java/com/facebook/presto/operator/scalar/SplitToMultimapFunction.java:71

        Multimap<Slice, Slice> multimap = ArrayListMultimap.create();
        int entryStart = 0;
        while (entryStart < string.length()) {
            // Extract key-value pair based on current index
            // then add the pair if it can be split by keyValueDelimiter
            Slice keyValuePair;
            int entryEnd = string.indexOf(entryDelimiter, entryStart);
            if (entryEnd >= 0) {
                keyValuePair = string.slice(entryStart, entryEnd - entryStart);
            }
            else {
                // The rest of the string is the last possible pair.
                keyValuePair = string.slice(entryStart, string.length() - entryStart);
            }

            int keyEnd = keyValuePair.indexOf(keyValueDelimiter);
            if (keyEnd < 0) {
                throw new PrestoException(INVALID_FUNCTION_ARGUMENT, "Key-value delimiter must appear exactly once in each entry. Bad input: " + keyValuePair.toStringUtf8());
            }

            int valueStart = keyEnd + keyValueDelimiter.length();
            Slice key = keyValuePair.slice(0, keyEnd);
            Slice value = keyValuePair.slice(valueStart, keyValuePair.length() - valueStart);
            if (value.indexOf(keyValueDelimiter) >= 0) {
                throw new PrestoException(INVALID_FUNCTION_ARGUMENT, "Key-value delimiter must appear exactly once in each entry. Bad input: " + keyValuePair.toStringUtf8());
            }

            multimap.put(key, value);

            if (entryEnd < 0) {
                // No more pairs to add
                break;
            }
            // Next possible pair is placed next to the current entryDelimiter
            entryStart = entryEnd + entryDelimiter.length();
        }

View on GitHub (pinned to 55bb57d202)

Solutions

  1. Ensure every entry contains the key-value delimiter; clean input first (remove empty/bare tokens).
  2. Use the correct delimiter for the data format.
  3. Wrap the call in try() to degrade to NULL on malformed entries.
  4. Pre-split manually (split → unnest → filter entries containing '=' → rebuild) to skip bad pairs.

Example fix

-- before
SELECT split_to_multimap('a=1,b', '=', ',');
-- after
SELECT split_to_multimap('a=1,b=2', '=', ',');
Defensive patterns

Strategy: validation

Validate before calling

SELECT split_to_multimap(array_join(filter(split(s, ','), e -> contains(e, '=')), ','), '=', ',')

Try / catch

SELECT try(split_to_multimap(s, '=', ',')) AS mm;

When it happens

Trigger: split_to_multimap('a=1,b', '=', ',') — entry 'b' has no '='; empty entries produced by trailing delimiters; wrong key-value delimiter passed.

Common situations: Malformed 'k=v' lists from configs or URLs (bare tokens, trailing separators), delimiter mismatch after data format change.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/37977dd4472c5dea. Report an issue: GitHub.