--- title: "list_bit_xor" slug: "dev-database-reference-sql-functions-binary-hash-uuid-list-bit-xor" updated: 2026-10-30T18:18:51Z published: 2026-10-30T18:18:51Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-binary-hash-uuid-list-bit-xor" --- > ## Documentation Index > Fetch the complete documentation index at: https://docs.vastdata.com/llms.txt > Use this file to discover all available pages before exploring further. # list_bit_xor *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Binary, hash and UUID functions](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid) › Bitwise list aggregates.* Combines the elements of a list with bitwise exclusive OR: a bit is set in the result if it's set in an odd number of the non-NULL elements. It works on lists of integers and of `BIT` values, and returns one value per row. ## Syntax ``` list_bit_xor(l) ``` | Argument | Type | Description | | --- | --- | --- | | `l` | a list of integers (`TINYINT[]` to `HUGEINT[]`, signed or unsigned) or of `BIT` values | The list to combine. | **Returns:** the element type of the list: `list_bit_xor` of a `BIGINT[]` is a `BIGINT`, of a `TINYINT[]` a `TINYINT`, of a `BIT[]` a `BIT`. ## Set up the examples The examples connect with the ADBC driver, as in [VAST Query Engine (ADBC)](/develop/docs/dev-database-integrations-adbc), and work in a schema called `docs_sql_fn_binary_hash_uuid_list_bit_xor`. Set `QE_ENDPOINT`, `AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY` and `VASTDB_BUCKET` ([SQL reference](/develop/docs/dev-database-reference-sql-index#example-connect-and-use-a-transaction)), and run the blocks in order in one Python session. Below each block is the output you should see. This block connects, defines the `run()` and `plan()` helpers, and creates a table of six rows, each with a list of bit masks. Row 2 has an empty list, row 3 has no list, and row 5 has a NULL element: ``` import os import re import adbc_driver_manager import adbc_driver_manager.dbapi as dbapi import adbc_driver_vastdb BUCKET = os.environ["VASTDB_BUCKET"] SCHEMA = f'"{BUCKET}/docs_sql_fn_binary_hash_uuid_list_bit_xor"' conn = dbapi.connect( driver=adbc_driver_vastdb.get_driver_path(), db_kwargs={ "vast.db.endpoint": os.environ["QE_ENDPOINT"], "vast.db.access_key": os.environ["AWS_ACCESS_KEY_ID"], "vast.db.secret_key": os.environ["AWS_SECRET_ACCESS_KEY"], }, autocommit=True, ) def server_message(e): """The server's message in a driver error, without the request ID or the echoed statement.""" text = re.sub(r"\[req=0x[0-9a-f]+\]: ", "", str(e)) found = (re.search(r'message: "(.*?)", request_id', text, re.S) or re.search(r"description: (.*)\)", text, re.S)) message = found.group(1) if found else text.strip().splitlines()[-1] message = re.sub(r"^Plan query: '.*?' failed with: ", "", message, flags=re.S) message = re.split(r"\\n|\n", message)[0].replace('\\"', '"') return message.replace(BUCKET, "") def run(sql): """Run one statement. Print the rows it returns, or the error.""" try: with conn.cursor() as cur: cur.execute(sql) rows = cur.fetchall() if cur.description else [] except (adbc_driver_manager.Error, OSError) as e: print(f"{type(e).__name__}: {server_message(e)}") else: print(rows) def plan(sql): """Print the plan without its ~N Rows lines: the table's row count, which can still be 0 just after an insert.""" with conn.cursor() as cur: cur.execute("EXPLAIN " + sql) steps = cur.fetchall()[0][1] print("\n".join(line for line in steps.splitlines() if "Rows" not in line)) TABLE = f"{SCHEMA}.masks" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, masks BIGINT[])") run(f"INSERT INTO {TABLE} VALUES " "(1, [1, 2, 3]), (2, []), (3, NULL), (4, [-1, 0]), (5, [7, NULL, 1]), (6, [255, 15, 240])") ``` ``` [] [] [(6,)] ``` ## What it does `list_bit_xor(l)` applies exclusive OR across the elements of `l`, skipping NULL elements: - `list_bit_xor([12, 10])` is `6`: `1100` XOR `1010` is `0110`. `list_bit_xor([12, 10, 6])` is `0`. - A list of one element returns that element: `list_bit_xor([5])` is `5`. - NULL elements are skipped: `list_bit_xor([12, NULL, 10])` is `6`. - A list with no non-NULL elements, empty or all NULL, returns NULL. - Negative integers take part in two's complement: `list_bit_xor([-1, 1])` is `-2`. - For a list of `BIT` values, every element must have the same number of bits. Cast the result to `VARCHAR` to read it, as for any `BIT` value ([BIT values](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-bit-values)). ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL` or `NULL::INTEGER[]` | `NULL` | | `[]::INTEGER[]` (empty list) | `NULL` | | `[NULL, NULL]::INTEGER[]` | `NULL` | | `[12, NULL, 10]` | `6`: NULL elements are skipped | | `[-1, 1]` | `-2` | | `[9223372036854775807, -9223372036854775808]` | `-1` | | `[255::UTINYINT, 15::UTINYINT]` | `240`, a `UTINYINT` | | `['1100'::BIT, '1010'::BIT]`, cast to `VARCHAR` | `'0110'` | | `['1100'::BIT, '10'::BIT]` | Error: `Cannot XOR bit strings of different sizes` | | `[true, false]`, `[1.5, 2.5]`, `['a', 'b']` or a list of lists | Error: `Binder Error: No matching aggregate function`; the next line of the message names the element type, such as `bit_xor(BOOLEAN)` | | A number, string or other non-list | Error: `Binder Error: No function matches the given name and argument types 'list_aggr(INTEGER_LITERAL, STRING_LITERAL)'. You might need to add explicit type casts.` (the types named are those of the argument) | The same cases, as the cluster returns them. They use the helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-list-bit-xor#set-up-the-examples): ``` run("SELECT list_bit_xor(NULL), list_bit_xor(NULL::INTEGER[]), list_bit_xor([]::INTEGER[]), " "list_bit_xor([NULL, NULL]::INTEGER[]), list_bit_xor([12, NULL, 10]), list_bit_xor([-1, 1])") run("SELECT list_bit_xor([9223372036854775807, -9223372036854775808]), list_bit_xor([255::UTINYINT, 15::UTINYINT]), " "typeof(list_bit_xor([255::UTINYINT, 15::UTINYINT]))") run("SELECT CAST(list_bit_xor(['1100'::BIT, '1010'::BIT]) AS VARCHAR)") run("SELECT list_bit_xor(['1100'::BIT, '10'::BIT])") run("SELECT list_bit_xor([true, false])") run(f"SELECT list_bit_xor(123) FROM {TABLE} LIMIT 1") ``` ``` [(None, None, None, None, 6, -2)] [(-1, 240, 'UTINYINT')] [('0110',)] OSError: Cannot XOR bit strings of different sizes InternalError: Binder Error: No matching aggregate function InternalError: Binder Error: No function matches the given name and argument types 'list_aggr(INTEGER_LITERAL, STRING_LITERAL)'. You might need to add explicit type casts. ``` ## Examples The parity of each bit across the masks in a row. Row 5's NULL element is skipped, and rows 2 and 3 have nothing to combine: ``` run(f"SELECT id, masks, list_bit_xor(masks) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, [1, 2, 3], 0), (2, [], None), (3, None, None), (4, [-1, 0], -1), (5, [7, None, 1], 6), (6, [255, 15, 240], 0)] ``` Keep the rows where the lowest bit is set in an odd number of masks: ``` run(f"SELECT id, masks FROM {TABLE} WHERE list_bit_xor(masks) & 1 = 1 ORDER BY id LIMIT 10") ``` ``` [(4, [-1, 0])] ``` ## How it runs in VAST The Query Engine runs on the cluster's CNodes, and a query on a table starts with a scan in VAST DataBase (`VAST_SCAN`). The scan reads a list column whole, and `list_bit_xor()` always runs in the Query Engine: - **In the `SELECT` list,** a projection step computes the result for each row after the scan. - **In `WHERE`,** the scan sends the list for every row, and a `FILTER` step above the scan computes the condition. The plan of the `WHERE` example shows the `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE list_bit_xor(masks) & 1 = 1") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ((list_aggr(masks, │ │ 'bit_xor') & 1) = 1) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ masks │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Store the combined mask if you filter on it often.** Compute it when you write the rows and keep it in its own column: a comparison of that column with a constant is evaluated in VAST DataBase, and the function of the list isn't. - **Add a condition on a plain column.** A comparison of a column with a constant, such as `id > 1`, is evaluated in VAST DataBase, so `list_bit_xor` runs only on the rows that pass it. The plan for `id > 1` alone has no `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE id > 1") ``` ``` ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` ## Limitations and errors - **Integers and `BIT` values only.** `BOOLEAN`, `DECIMAL`, `VARCHAR` and `DATE` lists, and lists of lists, fail with `Binder Error: No matching aggregate function`. - **The argument must be a list.** Anything else fails with `Binder Error: No function matches the given name and argument types 'list_aggr(...)'`; the message names `list_aggr` because the function is a form of [list_aggregate](/develop/docs/dev-database-reference-sql-functions-lists-list-aggregate). - **`BIT` elements must have the same size.** Otherwise the query fails with `Cannot XOR bit strings of different sizes`. - **The `bit_xor` aggregate isn't available.** `SELECT bit_xor(x) FROM t` fails with `The operator 'UNGROUPED_AGGREGATE' type=8 is currently not supported for this usage`. To combine values within a row, put them in a list and use `list_bit_xor`; to combine them across rows, do it in your client. - **`ORDER BY` needs a `LIMIT`.** Without one, the query fails with `The operator 'ORDER_BY' type=1 is currently not supported for this usage`. ``` run(f"SELECT bit_xor(id) FROM {TABLE}") ``` ``` InternalError: The operator 'UNGROUPED_AGGREGATE' type=8 is currently not supported for this usage. ``` ## Similar functions | Function | Result for `[12, 10]` | | --- | --- | | `list_bit_xor(l)` | `6`: the bits set in an odd number of elements | | [list_bit_and](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-list-bit-and) | `8`: the bits set in every element | | [list_bit_or](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-list-bit-or) | `14`: the bits set in any element | | [list_aggregate](/develop/docs/dev-database-reference-sql-functions-lists-list-aggregate)`(l, 'bit_xor')` | the same as `list_bit_xor` | | [xor](/develop/docs/dev-database-reference-sql-functions-numeric-xor) | `xor(12, 10)` is `6`: two values, not a list | ``` run("SELECT list_bit_xor(l), list_bit_and(l), list_bit_or(l), list_aggregate(l, 'bit_xor'), xor(12, 10) " "FROM (SELECT [12, 10] AS l)") ``` ``` [(6, 8, 14, 6, 6)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Binary, hash and UUID functions](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid): all the bit and binary functions. - [Bitwise operators on BIT values](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-bitwise-operators-on-bit) and [BIT values](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-bit-values). - [Where filters run](/develop/docs/dev-database-reference-sql-select#where-filters-run) and [pushdowns](/develop/docs/dev-database-reference-pushdowns). - [EXPLAIN](/develop/docs/dev-database-reference-sql-explain): how to read a plan.