-- Get the number of entries in a map
SELECT cardinality(r['map_col']) as size
FROM duckdb.query($$ SELECT MAP(['a', 'b', 'c'], [1, 2, 3]) as map_col $$) r;
-- Returns: 3

-- Empty map
SELECT cardinality(r['map_col']) as size
FROM duckdb.query($$ SELECT MAP([], []) as map_col $$) r;
-- Returns: 0

-- Get value for a specific key
SELECT element_at(r['map_col'], 'a') as value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: {1}

-- Non-existent key
SELECT element_at(r['map_col'], 'c') as value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: {}

-- Merge two maps
SELECT map_concat(r1['map1'], r2['map2']) as merged
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map1 $$) r1,
     duckdb.query($$ SELECT MAP(['b', 'c'], [3, 4]) as map2 $$) r2;
-- Returns: {a=1, b=3, c=4}

-- Note: 'b' value from map2 (3) overwrites map1's value (2)

-- Check if key exists
SELECT map_contains(r['map_col'], 'a') as has_key
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: t (true)

-- Check for non-existent key
SELECT map_contains(r['map_col'], 'c') as has_key
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: f (false)

-- Check if key-value pair exists
SELECT map_contains_entry(r['map_col'], 'a', 1) as has_entry
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: t (true)

-- Check with wrong value for existing key
SELECT map_contains_entry(r['map_col'], 'a', 2) as has_entry
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: f (false)

-- Check if value exists
SELECT map_contains_value(r['map_col'], 1) as has_value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: t (true)

-- Check for non-existent value
SELECT map_contains_value(r['map_col'], 3) as has_value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: f (false)

-- Get all key-value pairs as structs
SELECT map_entries(r['map_col']) as entries
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: {"(a,1)","(b,2)"}

-- Access individual struct fields
SELECT unnest(map_entries(r['map_col'])) as entry
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;

-- Extract value from a map
SELECT map_extract(r['map_col'], 'a') as value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: {1}

-- Extract non-existent key
SELECT map_extract(r['map_col'], 'c') as value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: {}

-- Extract single value (not as array)
SELECT map_extract_value(r['map_col'], 'a') as value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: 1

-- Non-existent key returns NULL
SELECT map_extract_value(r['map_col'], 'c') as value
FROM duckdb.query($$ SELECT MAP(['a', 'b'], [1, 2]) as map_col $$) r;
-- Returns: NULL

-- Create map from array of structs
SELECT map_from_entries(r['entries']) as new_map
FROM duckdb.query($$
    SELECT [{'k': 'a', 'v': 1}, {'k': 'b', 'v': 2}] as entries
$$) r;
-- Returns: {a=1, b=2}

-- This is the inverse operation of map_entries
SELECT map_from_entries(map_entries(r['map_col'])) as reconstructed
FROM duckdb.query($$ SELECT MAP(['x', 'y'], [10, 20]) as map_col $$) r;
-- Returns: {x=10, y=20}

-- Get all keys from a map
SELECT map_keys(r['map_col']) as keys
FROM duckdb.query($$ SELECT MAP(['a', 'b', 'c'], [1, 2, 3]) as map_col $$) r;
-- Returns: {a,b,c}

-- Empty map
SELECT map_keys(r['map_col']) as keys
FROM duckdb.query($$ SELECT MAP([], []) as map_col $$) r;
-- Returns: {}

-- Get all values from a map
SELECT map_values(r['map_col']) as values
FROM duckdb.query($$ SELECT MAP(['a', 'b', 'c'], [1, 2, 3]) as map_col $$) r;
-- Returns: {1,2,3}

-- Empty map
SELECT map_values(r['map_col']) as values
FROM duckdb.query($$ SELECT MAP([], []) as map_col $$) r;
-- Returns: {}