h3_toparent function

Returns the parent H3 cell of the input H3 cell at the specified resolution.

Since: Databricks Runtime 11.2

Syntax

h3_toparent ( h3cellIdExpr, resolutionExpr )

Arguments

  • h3CellIdExpr: A BIGINT expression, or a hexadecimal STRING expression representing an H3 cell ID.

  • resolutionExpr : An INT expression, whose value is expected to be between 0 and h3_resolution(h3CellIdExpr) inclusive, specifying the resolution of the parent H3 cell ID.

Returns

A value of the same type as the type of the h3CellIdExpr expression, corresponding to the parent H3 cell ID of the input H3 cell at the specified resolution.

The function returns NULL if any of the two input expressions is NULL. The function does partial validation regarding whether the input argument is a valid H3 cell ID. A necessary, but not sufficient condition for a valid H3 ID is that its value is between 0x08001fffffffffff and 0x08ff3b6db6db6db6. The behavior of the function is undefined if the input cell ID is not a valid cell ID. If the value of the resolutionExpr is equal to the resolution of the input H3 cell ID, the input H3 cell ID is returned.

Error conditions

  • If h3CellIdExpr is a STRING that cannot be converted to a BIGINT or corresponds to a BIGINT value that is smaller than 0x08001fffffffffff or larger than 0x08ff3b6db6db6db6, the function returns H3_INVALID_CELL_ID.

  • If resolutionExpr is smaller than 0 or larger than h3_resolution(h3CellIdExpr), the function returns H3_INVALID_RESOLUTION_VALUE.

Examples

-- Simple example taking a long as input.
> SELECT h3_toparent(599686042433355775, 0)
  577199624117288959

-- Simple example taking a valid hexadecimal string as input.
> SELECT h3_toparent('85283473fffffff', 0)
  8029fffffffffff

-- First input is an invalid H3 cell ID.
> SELECT h3_toparent(0, 0)
  [H3_INVALID_CELL_ID] 0 is not a valid H3 cell ID

-- Second input is an invalid resolution value.
> SELECT h3_toparent('85283473fffffff', -1)
  [H3_INVALID_RESOLUTION_VALUE] H3 resolution -1 must be between 0 and 5, inclusive