--- title: "from_base64" slug: "dev-database-reference-sql-functions-binary-hash-uuid-from-base64" updated: 2026-10-30T18:18:56Z published: 2026-10-30T18:18:56Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-binary-hash-uuid-from-base64" --- > ## 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. # from_base64 *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) › Binary data and encodings.* Reads Base64 text and returns the bytes it encodes, as a `BLOB`. It's the reverse of [to_base64](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-to-base64). Text that isn't padded standard Base64 stops the query with an error. ## Syntax ``` from_base64(s) ``` | Argument | Type | Description | | --- | --- | --- | | `s` | `VARCHAR` | Base64 text, standard alphabet, padded with `=` to a multiple of four characters. | **Returns:** `BLOB`. ## 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_from_base64`. 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 tokens: Base64 text and a note. Row 2's token is empty and row 3 has no values. The notes aren't Base64: ``` 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_from_base64"' 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}.tokens" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, b64 VARCHAR, note VARCHAR)") run(f"INSERT INTO {TABLE} VALUES " "(1, 'aGVsbG8=', 'hello'), " "(2, '', 'empty'), " "(3, NULL, NULL), " "(4, 'AP8=', 'two bytes'), " "(5, 'w6k=', 'UTF-8 text'), " "(6, 'YQ==', 'a')") ``` ``` [] [] [(6,)] ``` ## What it does `from_base64(s)` reads every four characters of `s` as three bytes, using the standard Base64 alphabet (`A`-`Z`, `a`-`z`, `0`-`9`, `+`, `/`) and `=` for padding: - `from_base64('aGVsbG8=')` is `b'hello'`, and `from_base64('aGVsbA==')` is `b'hell'`. - `from_base64('+/8=')` is `b'\xfb\xff'`. - `from_base64('')` is empty bytes. The text must be exact: its length a multiple of four, padding included, with no spaces or line breaks, and only characters from the standard alphabet. Anything else stops the query with `Could not decode string "..." as base64:` followed by the reason. One invalid value fails the whole query, not only its row. The result is bytes. If they're UTF-8 text, read them with [decode](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-decode): `decode(from_base64('w6k='))` is `'é'`. ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL` | `NULL` | | `''` (empty string) | `b''`, empty bytes | | `'aGVsbA=='` | `b'hell'` | | `'+/8='` | `b'\xfb\xff'` | | `'aGVsbG8'` (padding left out) | Error: `Could not decode string "aGVsbG8" as base64: length must be a multiple of 4` | | `'aGVs bG8='` (a space inside) | Error: `Could not decode string "aGVs bG8=" as base64: length must be a multiple of 4` | | `'YQ==='` (too much padding) | Error: `Could not decode string "YQ===" as base64: length must be a multiple of 4` | | `'-_8='` (the URL-safe alphabet) | Error: `Could not decode string "-_8=" as base64: invalid byte value '45' at position 0` | | `'===='` | Error: `Could not decode string "====" as base64: invalid byte value '61' at position 0` | | A number, `BLOB`, date, boolean or list | Error: `Binder Error: No function matches the given name and argument types`, for example `'from_base64(INTEGER_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-binary-hash-uuid-from-base64#set-up-the-examples): ``` run("SELECT from_base64(NULL), from_base64(''), from_base64('aGVsbA=='), from_base64('+/8=')") run("SELECT from_base64('aGVsbG8')") run("SELECT from_base64('aGVs bG8=')") run("SELECT from_base64('YQ===')") run("SELECT from_base64('-_8=')") run("SELECT from_base64('====')") run("SELECT from_base64(123)") ``` ``` [(None, b'', b'hell', b'\xfb\xff')] OSError: Could not decode string "aGVsbG8" as base64: length must be a multiple of 4 OSError: Could not decode string "aGVs bG8=" as base64: length must be a multiple of 4 OSError: Could not decode string "YQ===" as base64: length must be a multiple of 4 OSError: Could not decode string "-_8=" as base64: invalid byte value '45' at position 0 OSError: Could not decode string "====" as base64: invalid byte value '61' at position 0 InternalError: Binder Error: No function matches the given name and argument types 'from_base64(INTEGER_LITERAL)'. You might need to add explicit type casts. ``` ## Examples The bytes each token encodes. Row 5's bytes are the UTF-8 encoding of `é`, which `decode` turns back into text: ``` run(f"SELECT id, b64, from_base64(b64) FROM {TABLE} ORDER BY id LIMIT 10") run(f"SELECT id, decode(from_base64(b64)) FROM {TABLE} WHERE id = 5") ``` ``` [(1, 'aGVsbG8=', b'hello'), (2, '', b''), (3, None, None), (4, 'AP8=', b'\x00\xff'), (5, 'w6k=', b'\xc3\xa9'), (6, 'YQ==', b'a')] [(5, 'é')] ``` Text that isn't Base64 fails the query. `'hello'` has five characters, not a multiple of four: ``` run(f"SELECT id, from_base64(note) FROM {TABLE} WHERE id = 1") ``` ``` OSError: Could not decode string "hello" as base64: length must be a multiple of 4 ``` ## 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`). Where `from_base64` runs depends on its argument: - **`from_base64` of a column** is computed in the Query Engine for each row the scan returns. In `WHERE`, the scan sends the column for every row and a `FILTER` step tests it. - **`from_base64` of a constant** is computed once, before the scan. A comparison of a `BLOB` column with it, such as `data = from_base64('JVBERg==')`, is pushed down to VAST DataBase. The plan of a condition on `from_base64(b64)` shows the `FILTER` step above the scan: ``` plan(f"SELECT id FROM {TABLE} WHERE from_base64(b64) = '\\x61'::BLOB") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ (from_base64(b64) = 'a': │ │ :BLOB) │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ b64 │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Encode the constant instead of decoding the column.** `b64 = to_base64('\x61'::BLOB)` compares the stored text with a constant, which VAST DataBase can evaluate, and finds the same rows as `from_base64(b64) = '\x61'::BLOB` when the stored text is canonical Base64: ``` run(f"SELECT id FROM {TABLE} WHERE b64 = to_base64('\\x61'::BLOB) ORDER BY id LIMIT 10") plan(f"SELECT id FROM {TABLE} WHERE b64 = to_base64('\\x61'::BLOB)") ``` ``` [(6,)] ┌───────────────────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ Projections: id │ │ │ └───────────────────────────┘ ``` - **Store bytes as `BLOB`.** If you query the decoded bytes often, decode them once when you load the data and keep them in a `BLOB` column. A comparison of that column with a constant is pushed down. ## Limitations and errors - **Exact, padded, standard Base64 only.** Text without padding, with spaces or line breaks, or in the URL-safe alphabet (`-` and `_`) fails. Clean it up in your client before loading it, or before the query. - **No URL-safe variant.** `from_base64url` doesn't exist, and fails with `Scalar Function with name from_base64url does not exist!`. - **Invalid text fails the query.** There's no form that returns NULL instead. Leave such rows out with `WHERE`. - **`VARCHAR` only.** A `BLOB`, a number, a date or a boolean fails with `No function matches the given name and argument types`. ``` run("SELECT from_base64url('YQ')") ``` ``` InternalError: Catalog Error: Scalar Function with name from_base64url does not exist! ``` ## Similar functions | Function | Reads | Result for the bytes `\x00\xFF` | | --- | --- | --- | | `from_base64(s)` | Base64 text | from `'AP8='` | | [from_hex](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-from-hex) | hexadecimal text | from `'00FF'` | | [to_base64](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-to-base64) | the reverse | `'AP8='`; `from_base64(to_base64(b)) = b` | ``` run("SELECT from_base64('AP8='), from_hex('00FF'), to_base64('\\x00\\xFF'::BLOB), " "from_base64(to_base64('\\x00\\xFF'::BLOB)) = '\\x00\\xFF'::BLOB") ``` ``` [(b'\x00\xff', b'\x00\xff', 'AP8=', True)] ``` 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#binary-data-and-encodings): all the binary functions. - [to_base64](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-to-base64), [decode](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-decode) and [BLOB values](/develop/docs/dev-database-reference-sql-functions-binary-hash-uuid-blob-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.