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Google Cloud Spanner into Apache Arrow with ADBC

Google Cloud Spanner (emulator + PGAdapter 0.55), read and written through adbcBridge — the ADBC driver that loads the database's ODBC driver — verified on Linux, macOS arm64 and Windows x64. Everything below is the compatibility matrix's record for this row.

Status

Driver and connection string

ODBC driver

psqlodbc 16 (PG wire)

Wire

PostgreSQL wire

adbcBridge

0.1.1 (release)

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

Driver={drv};Server=127.0.0.1;Port=15442;Database=test-database;Uid=adbc;

Python

import adbcbridge

# {drv}: the ODBC driver library (path), or its name from odbcinst.ini
conn = adbcbridge.connect(uri="Driver={drv};Server=127.0.0.1;Port=15442;Database=test-database;Uid=adbc;")
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 Google Cloud Spanner 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

two driver quirks, both keyed on a PGAdapter-only setting because version() just says PostgreSQL 14.1: psqlodbc inlines a parameter array's timestamps as '...'::timestamp, a type Spanner does not have, so a batch binding a timestamp goes row-at-a-time (no_timestamp_param_arrays); and every Spanner table needs a PRIMARY KEY, so generated ingest DDL adds a surrogate GENERATED BY DEFAULT AS IDENTITY column (ingest_key_column).

What this stack needed

• Server side: no 32-bit integer, no TIMESTAMP WITHOUT TIME ZONE (so ts reads back zone-aware), no modifier on NUMERIC, no DDL inside a transaction; also ingests into and reads back an INTERLEAVE IN PARENT child table.
• A third quirk on the same key is Spanner's ceiling of 950 parameters per statement (max_statement_params): PGAdapter prepares a multi-row INSERT that carries more without complaint and then closes the connection at SQLExecute (08S01), leaving the batching's halving search no connection to halve on -- measured exactly, 948 parameters go through and 952 drop the connection -- so it is declared rather than probed, and ingest runs at 237 four-column rows per INSERT. ingest 7.3k rows/s (7.4k with array binding), fetch 95.8k rows/s at --rows 300 --fetch-rows 2000, which is the size this entry is benchmarked at

Native ADBC driver, compared

Google Cloud Spanner speaks the PostgreSQL wire protocol, so Apache Arrow's native PostgreSQL ADBC driver (adbc-driver-postgresql 1.12.0) can be pointed at it too. On 2026-09-05 the same seven-step ADBC workload (connect, SELECT 1, DDL and inserts and a read, a 1,000-row adbc_ingest, table schema, catalog listing, read back) ran through both:

Where the native driver stops it is by design of that driver, not a defect of Google Cloud Spanner; the full table for all 28 wire-compatible databases, with each first error, is in the note.

Read next

• Where the native PostgreSQL and MySQL ADBC drivers stop on wire-compatible databases
• Where PostgreSQL-wire servers part company with PostgreSQL
• Two psqlodbc bugs that lost rows and narrowed integers, and two traps