--- title: "enum_code" slug: "dev-database-reference-sql-functions-enums-enum-code" updated: 2026-10-30T18:18:56Z published: 2026-10-30T18:18:56Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-enums-enum-code" --- > ## 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. # enum_code *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) › Position of a value.* Returns the position of an `ENUM` value in its type's list of values, counting from 0. ## Syntax ``` enum_code(e) ``` | Argument | Type | Description | | --- | --- | --- | | `e` | An `ENUM` value | The value whose position you want, for example `CAST(priority AS ENUM('low', 'mid', 'high'))`. | **Returns:** an unsigned integer: `UTINYINT` for `ENUM('low', 'mid', 'high')`, `USMALLINT` for an `ENUM` of 300 values. ## 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_enums_enum_code`. 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. `ENUM` isn't a column type, so the table stores the priority of five tickets as `VARCHAR`, and the queries cast it to the `ENUM` type held in `LEVEL`. The table also stores the priority's position (`priority_code`) and a requested priority that isn't always a valid value. Ticket 4 has no values. This block connects, defines the `run()` and `plan()` helpers, and creates the table: ``` 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_enums_enum_code"' LEVEL = "ENUM('low', 'mid', 'high')" 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.sub(r"^Parse 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, ValueError) 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}.tickets" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, priority VARCHAR, priority_code BIGINT, requested VARCHAR)") run(f"INSERT INTO {TABLE} VALUES " "(1, 'low', 0, 'high'), " "(2, 'high', 2, 'HIGH'), " "(3, 'mid', 1, 'mid'), " "(4, NULL, NULL, NULL), " "(5, 'low', 0, 'none')") ``` ``` [] [] [(5,)] ``` ## What it does An `ENUM` type is a fixed list of values in a declared order, such as `ENUM('low', 'mid', 'high')`. `enum_code` returns where a value sits in that list: `'low'` is `0`, `'mid'` is `1` and `'high'` is `2`. The order is the declared one, not the alphabetical one. You make an `ENUM` value with a cast: `'mid'::ENUM('low', 'mid', 'high')`, or `CAST(priority AS ENUM('low', 'mid', 'high'))` on a column. The cast is exact: a string that isn't one of the values, even only in case or spacing, fails with `Could not convert string '...' to UINT8`. [TRY_CAST](/develop/docs/dev-database-reference-sql-functions-conditional-and-cast-try-cast) returns NULL instead. The result is unsigned, and arithmetic on it stays unsigned: `enum_code('mid'::ENUM('low', 'mid', 'high')) + 1` is `2`, but a subtraction below zero fails. Cast it to `BIGINT` for arithmetic. ## NULLs and edge cases | Input | Result | | --- | --- | | `enum_code(NULL::ENUM('low', 'mid', 'high'))` | `NULL`, a `UTINYINT` | | `enum_code('only'::ENUM('only'))` | `0` | | `enum_code('v299'::ENUM('v0', ..., 'v299'))` (300 values) | `299`, a `USMALLINT` | | `enum_code(TRY_CAST('z' AS ENUM('low', 'mid', 'high')))` | `NULL` | | `enum_code('LOW'::ENUM('low', 'mid', 'high'))`, or `' low'`, `'z'`, `''` | Error: `Could not convert string 'LOW' to UINT8` | | `enum_code(1::ENUM('low', 'mid', 'high'))` | Error: `Unimplemented type for cast (INTEGER -> ENUM(...`, followed by the type | | `enum_code(NULL)` (an untyped NULL), or a string, number, list, date or boolean | Error: `This function needs an ENUM as an 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-enums-enum-code#set-up-the-examples). `BIG` is an `ENUM` of 300 values: ``` BIG = "ENUM(" + ", ".join(f"'v{i}'" for i in range(300)) + ")" run(f"SELECT enum_code(NULL::{LEVEL}), typeof(enum_code(NULL::{LEVEL})), enum_code('only'::ENUM('only')), " f"enum_code(TRY_CAST('z' AS {LEVEL}))") run(f"SELECT enum_code('v299'::{BIG}), typeof(enum_code('v299'::{BIG}))") run(f"SELECT enum_code('LOW'::{LEVEL})") run(f"SELECT enum_code(1::{LEVEL})") run("SELECT enum_code(NULL)") run("SELECT enum_code('low')") ``` ``` [(None, 'UTINYINT', 0, None)] [(299, 'USMALLINT')] OSError: Could not convert string 'LOW' to UINT8 OSError: Unimplemented type for cast (INTEGER -> ENUM('low', 'mid', 'high')) InternalError: Binder Error: This function needs an ENUM as an argument InternalError: Binder Error: This function needs an ENUM as an argument ``` ## Examples The position of each ticket's priority; it matches the stored `priority_code`: ``` run(f"SELECT id, priority, enum_code(CAST(priority AS {LEVEL})), priority_code FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 'low', 0, 0), (2, 'high', 2, 2), (3, 'mid', 1, 1), (4, None, None, None), (5, 'low', 0, 0)] ``` Keep the tickets of priority `mid` or higher. Comparing the `ENUM` values directly gives the same rows: ``` run(f"SELECT id FROM {TABLE} WHERE enum_code(CAST(priority AS {LEVEL})) >= 1 ORDER BY id LIMIT 10") run(f"SELECT id FROM {TABLE} WHERE CAST(priority AS {LEVEL}) >= 'mid'::{LEVEL} ORDER BY id LIMIT 10") ``` ``` [(2,), (3,)] [(2,), (3,)] ``` Read the requested priority with `TRY_CAST`, so that a value that isn't in the list gives NULL. With `CAST`, such a value fails the whole query: ``` run(f"SELECT id, requested, enum_code(TRY_CAST(requested AS {LEVEL})) FROM {TABLE} ORDER BY id LIMIT 10") run(f"SELECT id, enum_code(CAST(requested AS {LEVEL})) FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 'high', 2), (2, 'HIGH', None), (3, 'mid', 1), (4, None, None), (5, 'none', None)] OSError: Could not convert string 'HIGH' to UINT8 ``` ## 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`). VAST DataBase can evaluate a comparison of a column with a constant, but not a cast or a function of a column, so the cast to `ENUM` and `enum_code()` are always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine computes the code for each row it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine computes the condition and keeps the rows that match. No rows are skipped in storage. A comparison of two `ENUM` values runs the same way. The plan of the `WHERE` example shows the `FILTER` step above the scan: ``` plan(f"SELECT id FROM {TABLE} WHERE enum_code(CAST(priority AS {LEVEL})) >= 1") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ (enum_code(CAST(priority │ │ AS ENUM('low', 'mid', │ │ 'high'))) >= 1) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ priority │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Store the code if you filter on the order.** Compute it when you write the rows and keep it in its own integer column: `priority_code >= 1` compares a column with a constant, which VAST DataBase evaluates, so rows that don't match never leave storage. The plan has no `FILTER` step: ``` plan(f"SELECT id FROM {TABLE} WHERE priority_code >= 1") ``` ``` ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` ## Limitations and errors - **`ENUM` isn't a column type.** `CREATE TABLE` with an `ENUM` column fails with `ENUM type is not supported in table definitions`, and `CREATE TYPE ... AS ENUM` isn't available. Store the value as `VARCHAR`, or its code as an integer, and cast in the query. - **The Python client can't read an `ENUM` value.** `SELECT 'mid'::ENUM('low', 'mid', 'high')` fails in the client with `Parser error: Cannot find a dictionary batch with dict id: 0`. Return `enum_code()` or cast the value to `VARCHAR`. - **Only `ENUM` values.** A string, number or untyped NULL fails with `This function needs an ENUM as an argument`; cast it first. - **Unsigned results.** `enum_code(...) - enum_code(...)` below zero fails with `Overflow in subtraction of UINT8 (0 - 1)!`. Cast to `BIGINT` first. ``` run(f"SELECT 'mid'::{LEVEL}") run(f"SELECT 'mid'::{LEVEL}::VARCHAR, enum_code('mid'::{LEVEL})") run(f"SELECT enum_code('low'::{LEVEL}) - enum_code('mid'::{LEVEL})") run(f"SELECT enum_code('low'::{LEVEL})::BIGINT - enum_code('mid'::{LEVEL})::BIGINT") ``` ``` ArrowInvalid: Parser error: Cannot find a dictionary batch with dict id: 0 [('mid', 1)] OSError: Overflow in subtraction of UINT8 (0 - 1)! [(-1,)] ``` ## Similar functions | Expression | Result for `'mid'` | Note | | --- | --- | --- | | `enum_code('mid'::ENUM('low', 'mid', 'high'))` | `1` | counts from 0 | | [list_position](/develop/docs/dev-database-reference-sql-functions-lists-list-position): `list_position(enum_range(NULL::ENUM('low', 'mid', 'high')), 'mid')` | `2` | counts from 1; subtract 1 for the code | | `CASE priority WHEN 'low' THEN 0 WHEN 'mid' THEN 1 WHEN 'high' THEN 2 END` | `1` | no cast; NULL gives NULL | | [enum_range](/develop/docs/dev-database-reference-sql-functions-enums-enum-range): `enum_range(NULL::ENUM('low', 'mid', 'high'))[code + 1]` | `'mid'` | from a code back to the value | ``` run(f"SELECT enum_code('mid'::{LEVEL}), list_position(enum_range(NULL::{LEVEL}), 'mid'), " f"enum_range(NULL::{LEVEL})[enum_code('mid'::{LEVEL}) + 1]") run(f"SELECT id, priority, CASE priority WHEN 'low' THEN 0 WHEN 'mid' THEN 1 WHEN 'high' THEN 2 END, " f"list_position(['low', 'mid', 'high'], priority) - 1, enum_code(CAST(priority AS {LEVEL})) " f"FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, 2, 'mid')] [(1, 'low', 0, 0, 0), (2, 'high', 2, 2, 2), (3, 'mid', 1, 1, 1), (4, None, None, None, None), (5, 'low', 0, 0, 0)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [enum_first](/develop/docs/dev-database-reference-sql-functions-enums-enum-first), [enum_last](/develop/docs/dev-database-reference-sql-functions-enums-enum-last), [enum_range](/develop/docs/dev-database-reference-sql-functions-enums-enum-range) and [enum_range_boundary](/develop/docs/dev-database-reference-sql-functions-enums-enum-range-boundary): the values of an `ENUM` type. - [Binary, hash and UUID functions](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid): all the enum functions. - [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.