--- title: "list_sum" slug: "dev-database-reference-sql-functions-lists-list-sum" updated: 2026-10-30T18:19:11Z published: 2026-10-30T18:19:11Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-lists-list-sum" --- > ## 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_sum *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [List, struct and map functions](/develop/docs/dev-database-reference-sql-functions-lists-and-structs) › Aggregate a list.* Returns the sum of the elements of a list, one value per row. NULL elements are skipped. It's the same as `list_aggregate(l, 'sum')`. ## Syntax ``` list_sum(l) ``` | Argument | Type | Description | | --- | --- | --- | | `l` | a list of numbers or booleans | The list to add up. | **Returns:** `HUGEINT` for a list of integers or booleans (ADBC returns it as `DECIMAL(38, 0)`, which Python prints as `Decimal`); `DECIMAL(38, s)` for a list of decimals; `DOUBLE` for a list of `DOUBLE`. ## 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_lists_list_sum`. 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 five rows of lists of numbers and measurements. Row 3 has empty lists, row 4 has no values, and row 5 has measurements close to the largest `DOUBLE`: ``` 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_lists_list_sum"' 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}.samples" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, nums BIGINT[], vals DOUBLE[])") run(f"INSERT INTO {TABLE} VALUES " "(1, [1, 2, 3], [0.5, 2.5, -1.0]), " "(2, [3, NULL, 3], [2.0, NULL]), " "(3, [], []), " "(4, NULL, NULL), " "(5, [-5, 0, -5, 10], [1e308, 1e308, -1e-308])") ``` ``` [] [] [(5,)] ``` ## What it does `list_sum(l)` adds up the elements of `l` that aren't NULL. `list_sum([1, 2, 3])` returns `6`, and `list_sum([1, NULL, 2])` returns `3`. - **Integer sums don't overflow.** The sum of a list of integers is a `HUGEINT`, whatever the element type (`TINYINT`, `INTEGER`, `BIGINT`), so `list_sum([9223372036854775807, 1])` returns `9223372036854775808`, one more than the largest `BIGINT`. - **Decimals stay exact.** `list_sum([0.1, 0.2])` returns `Decimal('0.3')`, a `DECIMAL(38, 1)`. The same values as `DOUBLE` give `0.30000000000000004`. - **`DOUBLE` sums follow floating point.** A sum too large for `DOUBLE` returns `inf`, not an error; `inf` plus `-inf` returns `nan`, and a `NaN` element makes the sum `nan`. - **Booleans count as 1 and 0.** `list_sum([true, true, false])` returns `2`. ## NULLs and edge cases | Input | Result | | --- | --- | | `list_sum(NULL)` | `NULL` | | `list_sum(NULL::BIGINT[])` | `NULL` | | `list_sum([]::BIGINT[])` | `NULL`, not `0` | | `list_sum([NULL]::BIGINT[])` | `NULL` | | `list_sum([1, NULL, 2])` | `3` | | `list_sum([9223372036854775807, 1])` | `9223372036854775808` | | `list_sum([-9223372036854775808, -1])` | `-9223372036854775809` | | `list_sum([1.25, 2.50])` | `3.75` (`DECIMAL`) | | `list_sum([0.1::DOUBLE, 0.2::DOUBLE])` | `0.30000000000000004` | | `list_sum([1e308, 1e308])` | `inf` | | `list_sum(['inf'::DOUBLE, -'inf'::DOUBLE])` | `nan` | | `list_sum([true, true, false])` | `2` | | `list_sum(['a'])`, a list of intervals or of lists | Error: `Binder Error: No matching aggregate function` | | A number, string, date or other non-list | Error: `Binder Error: No function matches the given name and argument types`, for example `'list_aggr(INTEGER_LITERAL, STRING_LITERAL)'` | The same cases, as the cluster returns them. They use the table and helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-lists-list-sum#set-up-the-examples): ``` run("SELECT list_sum(NULL), list_sum(NULL::BIGINT[]), list_sum([]::BIGINT[]), list_sum([NULL]::BIGINT[]), list_sum([1, NULL, 2])") run("SELECT list_sum([9223372036854775807, 1]), list_sum([-9223372036854775808, -1]), list_sum([1.25, 2.50])") run("SELECT list_sum([0.1::DOUBLE, 0.2::DOUBLE]), list_sum([1e308, 1e308]), " "list_sum(['inf'::DOUBLE, -'inf'::DOUBLE]), list_sum([true, true, false])") run("SELECT list_sum(['a'])") run(f"SELECT list_sum(123) FROM {TABLE} LIMIT 1") ``` ``` [(None, None, None, None, Decimal('3'))] [(Decimal('9223372036854775808'), Decimal('-9223372036854775809'), Decimal('3.75'))] [(0.30000000000000004, inf, nan, Decimal('2'))] 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 sum of each row's numbers and measurements. Row 5's measurements are too large to add up as `DOUBLE`: ``` run(f"SELECT id, list_sum(nums), list_sum(vals) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, Decimal('6'), 2.0), (2, Decimal('6'), 2.0), (3, None, None), (4, None, None), (5, Decimal('0'), inf)] ``` The result types, for integers, decimals and doubles: ``` run("SELECT typeof(list_sum([1, 2])), typeof(list_sum([1.5, 2.5])), typeof(list_sum([1.5::DOUBLE]))") ``` ``` [('HUGEINT', 'DECIMAL(38,1)', 'DOUBLE')] ``` The rows whose numbers add up to more than 3: ``` run(f"SELECT id FROM {TABLE} WHERE list_sum(nums) > 3 ORDER BY id LIMIT 10") ``` ``` [(1,), (2,)] ``` ## 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_sum()` always runs in the Query Engine. It adds up within each row's list, so it's a scalar function: it returns one value per row and needs no `GROUP BY`. - **In the `SELECT` list,** a projection step computes the sum of each row's list after the scan. The plan has no `FILTER` step. - **In `WHERE`,** the scan sends the list for every row, and a `FILTER` step computes the sum and keeps the rows that match. No rows are skipped in storage. The plan of the `WHERE` example shows the `FILTER` step above the scan: ``` plan(f"SELECT id FROM {TABLE} WHERE list_sum(nums) > 3") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ (list_aggr(nums, 'sum') > │ │ 3) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ nums │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **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_sum()` 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 │ │ │ └───────────────────────────┘ ``` - **Store the sum if you filter on it often.** Compute it when you write the rows and keep it in its own column: `total > 3` is pushed down, `list_sum(nums) > 3` isn't. ## Limitations and errors - **Numbers and booleans only.** A list of text, intervals or lists fails with `No matching aggregate function`. A value that isn't a list fails with an error that names `list_aggr`, the function `list_sum` is built on. - **An empty list returns NULL.** Use `coalesce(list_sum(l), 0)` where you need `0`. - **Not across rows.** `list_sum` adds up within one row's list. The query below, which totals values over the rows of a table in subqueries, fails with `The operator 'UNGROUPED_AGGREGATE' type=8 is currently not supported for this usage`. - **`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 (SELECT sum(v) FROM (SELECT unnest(nums) AS v FROM {TABLE})) AS total, " f"(SELECT sum(list_sum(nums)) FROM {TABLE}) AS total2") ``` ``` InternalError: The operator 'UNGROUPED_AGGREGATE' type=8 is currently not supported for this usage. ``` ## Similar functions | Function | What it does | Result for `[3, 1, NULL, 3, 10]` | | --- | --- | --- | | `list_sum(l)` | sum of the elements | `17` | | [list_aggregate](/develop/docs/dev-database-reference-sql-functions-lists-list-aggregate)`(l, 'sum')` | the same, by name | `17` | | [list_reduce](/develop/docs/dev-database-reference-sql-functions-lists-list-reduce) with `(a, x) -> a + x` | the same with a lambda; NULL elements must be removed first | `17` | | [list_product](/develop/docs/dev-database-reference-sql-functions-lists-list-product)`(l)` | product of the elements | `90.0` | | [list_avg](/develop/docs/dev-database-reference-sql-functions-lists-list-avg)`(l)` | mean of the elements | `4.25` | | [sum](/develop/docs/dev-database-reference-sql-functions-aggregate-sum) | sum over the rows of a table | | ``` run("SELECT list_sum(l), list_aggregate(l, 'sum'), list_reduce(list_filter(l, x -> x IS NOT NULL), (a, x) -> a + x), " "list_product(l), list_avg(l) FROM (SELECT [3, 1, NULL, 3, 10] AS l)") ``` ``` [(Decimal('17'), Decimal('17'), 17, 90.0, 4.25)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [List, struct and map functions](/develop/docs/dev-database-reference-sql-functions-lists-and-structs#aggregate-a-list): all the list aggregates. - [sum](/develop/docs/dev-database-reference-sql-functions-aggregate-sum): the aggregate over rows. - [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.