--- title: "count_if" slug: "dev-database-reference-sql-functions-aggregate-count-if" updated: 2026-10-30T18:18:46Z published: 2026-10-30T18:18:46Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-aggregate-count-if" --- > ## 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. # count_if *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Aggregate and analytic functions](/develop/docs/dev-database-reference-sql-functions-aggregate) › Counting.* Counts the rows where a condition is true. `countif` is the same function. ## Syntax ``` count_if(condition) countif(condition) ``` | Argument | Type | Description | | --- | --- | --- | | `condition` | `BOOLEAN` | A condition or a `BOOLEAN` column. Rows where it's true are counted. | **Returns:** `HUGEINT`, a 128-bit integer. ADBC returns it as `DECIMAL(38, 0)`, which Python prints as `Decimal`. **Aliases:** `countif`. ## 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_aggregate_count_if`. 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 sensor readings. Reading 4 has no `ok` flag, and reading 5 has no values: ``` 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_aggregate_count_if"' 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}.readings" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, sensor VARCHAR, temperature DOUBLE, ok BOOLEAN)") run(f"INSERT INTO {TABLE} VALUES " "(1, 's1', 18.5, true), " "(2, 's1', 21.0, true), " "(3, 's2', 19.5, false), " "(4, 's2', 24.0, NULL), " "(5, NULL, NULL, NULL)") ``` ``` [] [] [(5,)] ``` ## What it does `count_if(condition)` is an aggregate: it evaluates the condition on each row and counts the rows where it's true. Rows where it's false or NULL aren't counted. The condition must be a `BOOLEAN`: a comparison (`temperature > 20`), a test (`sensor IS NULL`, `sensor LIKE 's%'`), a `BOOLEAN` column, or `NOT` of one. A number isn't taken as true or false: `count_if(1)` is an error. **On no rows, `count_if` returns NULL, not 0.** It also returns NULL when the condition is NULL on every row. Wrap it in [coalesce](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast-coalesce) to get 0, or use `count(*) FILTER (WHERE condition)`, which returns 0 (see [Similar functions](/develop/docs/dev-database-reference-sql-functions-aggregate-count-if#similar-functions)). ## NULLs and edge cases | Input | Result | | --- | --- | | Condition NULL on a row | That row isn't counted | | Condition false on every row | `0` | | Condition NULL on every row, or `count_if(NULL)` | NULL | | No rows (an empty table, or a `WHERE` that matches nothing) | NULL | | `coalesce(count_if(c), 0)` on no rows | `0` | | `count_if(x IS NULL)` | The rows where `x` is NULL | | `count_if(true)` with no `FROM` | `1` | | A number: `count_if(1)`, `count_if(id)` | Error: `No function matches the given name and argument types`, for example `'count_if(INTEGER)'` | | A string: `count_if('true')` | Error: `No function matches the given name and argument types 'count_if(VARCHAR)'` | | `count_if(DISTINCT c)` | Error: `The operator 'UNGROUPED_AGGREGATE' type=8 is currently not supported for this usage.` | 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-aggregate-count-if#set-up-the-examples): ``` run(f"SELECT count_if(ok), count_if(NOT ok), count_if(ok IS NULL), count_if(false) FROM {TABLE}") run(f"SELECT count_if(ok) FROM {TABLE} WHERE id = 5") run(f"SELECT count_if(ok), coalesce(count_if(ok), 0) FROM {TABLE} WHERE id > 100") run("SELECT count_if(true), count_if(NULL)") run(f"SELECT count_if(1) FROM {TABLE}") run(f"SELECT count_if('true') FROM {TABLE}") run(f"SELECT count_if(DISTINCT ok) FROM {TABLE}") ``` ``` [(Decimal('2'), Decimal('1'), Decimal('2'), Decimal('0'))] [(None,)] [(None, Decimal('0'))] [(Decimal('1'), None)] InternalError: Binder Error: No function matches the given name and argument types 'count_if(INTEGER)'. You might need to add explicit type casts. InternalError: Binder Error: No function matches the given name and argument types 'count_if(VARCHAR)'. You might need to add explicit type casts. InternalError: The operator 'UNGROUPED_AGGREGATE' type=8 is currently not supported for this usage. ``` ## Examples Several counts over the same rows in one query: readings above 20 degrees, readings flagged as not OK, and readings with no sensor name. `countif` gives the same result as `count_if`: ``` run(f"SELECT count_if(temperature > 20), countif(temperature > 20), count_if(NOT ok), " f"count_if(sensor IS NULL) FROM {TABLE}") ``` ``` [(Decimal('2'), Decimal('2'), Decimal('1'), Decimal('1'))] ``` The share of readings above 20 degrees. `/` returns a `DOUBLE`, so the result is a fraction: ``` run(f"SELECT count_if(temperature > 20) / count(*) FROM {TABLE}") ``` ``` [(0.4,)] ``` ## How it runs in VAST The Query Engine runs on the cluster's CNodes. A `count_if` query has two steps, which [EXPLAIN](/develop/docs/dev-database-reference-sql-explain) shows: 1. **A scan in VAST DataBase** (`VAST_SCAN`), which reads the columns the condition uses and evaluates the `WHERE` conditions it can [push down](/develop/docs/dev-database-reference-pushdowns). 2. **One aggregate step** (`UNGROUPED_AGGREGATE`) in the Query Engine. It evaluates the condition of `count_if` on every row the scan sends, and counts the rows where it's true. The condition inside `count_if` isn't pushed down: the scan sends every row, and the plan shows the condition inside the aggregate step, with no `FILTER` step: ``` plan(f"SELECT count_if(temperature > 20) FROM {TABLE}") ``` ``` ┌───────────────────────────┐ │ UNGROUPED_AGGREGATE │ │ ──────────────────── │ │ Aggregates: │ │ count_if((temperature > 20│ │ .0)) │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ temperature │ │ │ └───────────────────────────┘ ``` ## Make it faster - **For one count, put the condition in `WHERE`.** `SELECT count(*) FROM t WHERE temperature > 20` gives the same count (as a `BIGINT`, and 0 on no rows), and its condition is evaluated in VAST DataBase, so the rows that don't match never leave storage. The plan has no condition at all: ``` plan(f"SELECT count(*) FROM {TABLE} WHERE temperature > 20") ``` ``` ┌───────────────────────────┐ │ UNGROUPED_AGGREGATE │ │ ──────────────────── │ │ Aggregates: │ │ count_star() │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ └───────────────────────────┘ ``` - **For several counts, use one query.** Several `count_if` calls share one scan and one aggregate step; separate queries scan the table again each time. - **Combine it with a pushed-down condition.** In `SELECT count_if(ok) FROM t WHERE id > 100`, `id > 100` is still evaluated in VAST DataBase, so `count_if` sees only the rows that pass it. ## Limitations and errors - **`BOOLEAN` only.** A number, a string, a date or a list fails with `No function matches the given name and argument types`; the error lists the one form that exists, `count_if(BOOLEAN) -> HUGEINT`. Write a comparison: `count_if(n <> 0)`. - **NULL on no rows.** See [What it does](/develop/docs/dev-database-reference-sql-functions-aggregate-count-if#what-it-does). - **No `GROUP BY` or `DISTINCT`.** A count per group fails with `The operator 'HASH_GROUP_BY' type=9 is currently not supported.`; `count_if(DISTINCT ...)` fails with `The operator 'UNGROUPED_AGGREGATE' type=8 is currently not supported for this usage.` - **Window forms.** `count_if(c) OVER (ROWS UNBOUNDED PRECEDING)` runs, as a running count in the order the scan returns the rows. `OVER ()`, `OVER (ORDER BY ...)` and `OVER (PARTITION BY ...)` fail with `The operator 'WINDOW' type=6 is currently not supported.` See [window functions](/develop/docs/dev-database-reference-sql-functions-aggregate-window-functions). ``` run(f"SELECT count_if(id) FROM {TABLE}") run(f"SELECT count_if(id <> 0) FROM {TABLE}") run(f"SELECT sensor, count_if(ok) FROM {TABLE} GROUP BY sensor") ``` ``` InternalError: Binder Error: No function matches the given name and argument types 'count_if(BIGINT)'. You might need to add explicit type casts. [(Decimal('5'),)] InternalError: The operator 'HASH_GROUP_BY' type=9 is currently not supported. ``` ## Similar functions | Function | Counts | Returns | On no rows | | --- | --- | --- | --- | | `count_if(condition)` | rows where the condition is true | `HUGEINT` | NULL | | `count(*) FILTER (WHERE condition)` ([FILTER](/develop/docs/dev-database-reference-sql-functions-aggregate-filter-clause)) | rows where the condition is true | `BIGINT` | `0` | | `sum(CASE WHEN condition THEN 1 ELSE 0 END)` ([sum](/develop/docs/dev-database-reference-sql-functions-aggregate-sum)) | rows where the condition is true | `HUGEINT` | NULL | | `count(*) ... WHERE condition` ([count](/develop/docs/dev-database-reference-sql-functions-aggregate-count)) | rows where the condition is true; the condition can be pushed down | `BIGINT` | `0` | | [count](/develop/docs/dev-database-reference-sql-functions-aggregate-count) `(condition)` | rows where the condition isn't NULL: false is counted too | `BIGINT` | `0` | The same count four ways, then on no rows. The last column shows that `count(condition)` counts the false rows too: ``` run(f"SELECT count_if(temperature > 20), count(*) FILTER (WHERE temperature > 20), " f"sum(CASE WHEN temperature > 20 THEN 1 ELSE 0 END), count(temperature > 20) FROM {TABLE}") run(f"SELECT count(*) FROM {TABLE} WHERE temperature > 20") run(f"SELECT count_if(temperature > 20), count(*) FILTER (WHERE temperature > 20), " f"sum(CASE WHEN temperature > 20 THEN 1 ELSE 0 END), count(temperature > 20) FROM {TABLE} WHERE id > 100") ``` ``` [(Decimal('2'), 2, Decimal('2'), 4)] [(2,)] [(None, 0, None, 0)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Aggregate and analytic functions](/develop/docs/dev-database-reference-sql-functions-aggregate): all the aggregates, and the ones that aren't available. - [count](/develop/docs/dev-database-reference-sql-functions-aggregate-count), [FILTER](/develop/docs/dev-database-reference-sql-functions-aggregate-filter-clause) and [coalesce](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast-coalesce). - [Pushdowns](/develop/docs/dev-database-reference-pushdowns) and [EXPLAIN](/develop/docs/dev-database-reference-sql-explain).