Function decode_binary_array

tests/python/test_array_binary_debug.py:11–78

Decode PostgreSQL binary array format and show detailed structure.

(data: bytes)

from typing import Optional, List

def decode_binary_array(data: bytes) -> dict:
    """Decode PostgreSQL binary array format and show detailed structure."""

    if len(data) < 12:
        return {"error": f"Data too short: {len(data)} bytes"}

    offset = 0
    result = {}

    # Read header
    ndim = struct.unpack('>I', data[offset:offset+4])[0]
    offset += 4
    result['ndim'] = ndim

    dataoffset = struct.unpack('>I', data[offset:offset+4])[0]
    offset += 4
    result['dataoffset'] = dataoffset

    elemtype = struct.unpack('>I', data[offset:offset+4])[0]
    offset += 4
    result['elemtype'] = elemtype

    # Read dimensions
    dimensions = []
    for i in range(ndim):
        dim_size = struct.unpack('>I', data[offset:offset+4])[0]
        offset += 4
        lower_bound = struct.unpack('>I', data[offset:offset+4])[0]
        offset += 4
        dimensions.append({'size': dim_size, 'lower_bound': lower_bound})
    result['dimensions'] = dimensions

    # Read NULL bitmap if present
    if dataoffset > 0:
        bitmap_start = 20  # After header and 1 dimension
        bitmap_bytes = dataoffset - bitmap_start
        bitmap = data[bitmap_start:bitmap_start+bitmap_bytes]
        result['null_bitmap'] = bitmap.hex()
        result['null_bitmap_binary'] = ' '.join(f'{b:08b}' for b in bitmap)
        offset = dataoffset

    # Read elements
    elements = []
    total_elements = dimensions[0]['size'] if dimensions else 0

    for i in range(total_elements):
        elem_len = struct.unpack('>i', data[offset:offset+4])[0]
        offset += 4

        if elem_len == -1:
            elements.append({'index': i, 'length': -1, 'value': None, 'is_null': True})
        else:
            value_bytes = data[offset:offset+elem_len]
            offset += elem_len

            # For INT4, decode the value
            if elemtype == 23:  # INT4 OID
                value = struct.unpack('>i', value_bytes)[0]