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Firebird into Apache Arrow with ADBC

Firebird 5, read and written through adbcBridge — the ADBC driver that loads the database's ODBC driver — verified on Linux and Windows x64. Everything below is the compatibility matrix's record for this row.

Status

Driver and connection string

ODBC driver

Firebird ODBC 3.5.0-rc1

Wire

native ODBC

adbcBridge

0.1.1 (release)

The connection string the matrix used, as the connection strings reference records it (Databases with their own native protocol and ODBC driver); {drv} is the driver library or its name from odbcinst.ini, and the host, port and credentials are the test server's.

Driver={drv};DBNAME=inet://127.0.0.1:13050//var/lib/firebird/data/adbc.fdb;UID=adbc;PWD=adbc;CHARSET=UTF8;

Python

import adbcbridge

# {drv}: the ODBC driver library (path), or its name from odbcinst.ini
conn = adbcbridge.connect(uri="Driver={drv};DBNAME=inet://127.0.0.1:13050//var/lib/firebird/data/adbc.fdb;UID=adbc;PWD=adbc;CHARSET=UTF8;")
with conn.cursor() as cur:
    cur.execute("SELECT * FROM my_table")
    table = cur.fetch_arrow_table()      # pyarrow.Table

Polars and pandas

import polars as pl, pandas as pd

df = pl.read_database("SELECT * FROM my_table", connection=conn)   # Polars, Arrow-native
pdf = pd.read_sql("SELECT * FROM my_table", conn)                   # pandas 2.2+, ADBC connection

pip install adbcbridge brings the driver library; the Firebird ODBC driver is installed the way its vendor documents, then named in Driver=. Rust, Go, C# and Java use the same connection string through their ADBC driver managers — see the docs.

What the matrix recorded

SQL_C_WCHAR sized in 4-byte wchar_t; parameter arrays are off (no_param_arrays): with column-wise binding OdbcFb steps fixed-length C types at the BufferLength stride, so every row receives row 1's values with SQL_SUCCESS throughout (firebird-odbc-driver#299, reproduced in plain ODBC on 3.0.1 and 3.5.0-rc1).

What this stack needed

• Firebird's dialect has neither multi-row VALUES (-104 Token unknown at the second row-group's comma) nor Oracle's INSERT ALL, so bulk ingest batches through the third form it does take: INSERT INTO t (cols) SELECT CAST(? AS <type>), ... FROM RDB$DATABASE UNION ALL SELECT ... (multirow_union_from, probed like every other form and only after the standard one is refused).
• The CAST is not a guess and cannot lose anything -- it names the type ingest itself would create for that Arrow type, so a value too wide for the target column raises string right truncation on the INSERT's own assignment exactly as a one-row INSERT would; a column with no such exact type gets no batching.
• Firebird's 256-context limit caps it at ~250 row-groups.
• Also handled here: once a NULL has been bound to a SQL_BIGINT parameter with SQL_C_DEFAULT (whose ODBC default C type is SQL_C_CHAR), OdbcFb writes NULL for every later SQL_C_SBIGINT rebind of that parameter (#300) -- NULLs are bound SQL_C_SBIGINT (NullParamCType).
• SQL_ATTR_ROWS_FETCHED_PTR set before SQLPrepare is discarded (#301); the bridge sets it after execute and was not affected.
• Generated ingest DDL used to spell an Arrow string as BLOB SUB_TYPE TEXT -- what SQLGetTypeInfo(SQL_LONGVARCHAR) names.
• One run read a 100,000-row table with such a column at 8,256 rows/s against 1,004,277 without it; that slowdown could not be reproduced afterwards (2026-08-28: BLOB and VARCHAR columns both read at 300k+ rows/s, plain ODBC and through the bridge, driver 3.0.1 and 3.5.0-rc1), so it is not recorded as a driver property.
• Strings go in as VARCHAR(8191), legal in any character set (ddl_string_type_name), because the column can then be filtered and indexed and reads through ordinary bound columns; the same table ingested at 40,670 rows/s instead of 5,705 in that run.
• Values over 8,191 characters are refused on insert, as Db2's VARCHAR(32672) refuses its last 28 bytes.

Read next

• Which older engine releases pass the matrix entry unchanged
• Three ways Firebird's ODBC driver loses your parameters without saying so
• Five Windows-only ODBC failures are one thing wearing different clothes