INDEX_UNIQUE()

All functions > ARRAY OF ROWS > INDEX_UNIQUE()

Returns an index unique computed from the given array and key.

Signatures

Returns: Map from key values to array positions (1-based)

INDEX_UNIQUE(base: ARRAY<ROW<T>>, key: FIELD) → INDEX

Notes

• Creates a unique index mapping key values to array positions
• Each key maps to at most one position (the last occurrence if duplicates exist)
• Returns 1-based array indices
• NULL keys are excluded from the index
• Useful for efficient lookups with ELEMENT_AT_KEY
• If duplicate keys exist, keeps the last occurrence
• Use INDEX_MULTI for keys with multiple values

Examples

SELECT
    f1 := INDEX_UNIQUE(ARRAY[ROW(1 AS k, 'a' AS v), ROW(2 AS k, 'b' AS v)] BY k) -- Map each key to a single 1-based row index (equiv skipped: MAP has no FeatureQL literal)
;