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BigQuery Feature Comparison

Production BigQuery vs Go Emulator (goccy/bigquery-emulator) vs Python Rewrite (SQLGlot + DuckDB)

Date: 2026-04-20

Legend: Y = Supported | P = Partial | N = Not Supported | — = Not Applicable

Platform & Runtime

Feature	Production BQ	Go Emulator	Python Rewrite
ARM64 / Apple Silicon (native)	—	N (go-zetasql is x86-64 only, requires QEMU)	Y (DuckDB native ARM64)
Single binary / container	—	Y (Go static binary)	Y (Docker w/ Python)
In-process testing (same process)	—	Y (Go httptest)	Y (Python fixture)
Persistent storage	Y	Y (SQLite file)	Y (DuckDB file)
In-memory mode	Y	Y	Y

DDL Statements

Feature	Production BQ	Go Emulator	Python Rewrite
CREATE TABLE	Y	Y	Y
CREATE TABLE IF NOT EXISTS	Y	Y	Y
CREATE OR REPLACE TABLE	Y	Y	Y
CREATE TEMP TABLE	Y	Y	Y
CREATE TABLE LIKE / COPY / CLONE	Y	N	N (planned P2)
CREATE TABLE with PARTITION BY	Y	N (issue #152)	P (DDL accepted, metadata stored; no physical partitioning)
CREATE TABLE with CLUSTER BY	Y	N (issue #373, bug)	P (DDL accepted, metadata stored)
CREATE TABLE with OPTIONS	Y	P	P (SQLGlot drops OPTIONS silently; must intercept pre-transpile)
CREATE VIEW	Y	Y	Y
CREATE MATERIALIZED VIEW	Y	N	N (planned P2)
CREATE EXTERNAL TABLE	Y	N	N (planned P3)
CREATE SCHEMA	Y	N	Y
CREATE FUNCTION (SQL UDF)	Y	Y	Y (via DuckDB CREATE MACRO)
CREATE TABLE FUNCTION	Y	N	N
CREATE PROCEDURE	Y	N	N (planned P1, requires scripting interpreter)
CREATE SNAPSHOT TABLE	Y	N	N (planned P3)
CREATE ROW ACCESS POLICY	Y	N	N (stub)
CREATE SEARCH INDEX	Y	N	N (stub)
ALTER TABLE ADD COLUMN	Y	N (issue #412)	Y
ALTER TABLE DROP COLUMN	Y	N	Y
ALTER TABLE RENAME	Y	N	Y
ALTER TABLE SET OPTIONS	Y	N	P (SQLGlot truncates OPTIONS)
DROP TABLE / VIEW / FUNCTION / SCHEMA	Y	P (TABLE, VIEW, FUNCTION only)	Y

DML Statements

Feature	Production BQ	Go Emulator	Python Rewrite
INSERT	Y	Y	Y
UPDATE	Y	P (no UPDATE…FROM with joins, issue #310)	Y
DELETE	Y	Y	Y
TRUNCATE TABLE	Y	Y	Y
MERGE	Y	P (parser accepts, execution buggy: issues #128, #163, #299)	Y (SQLGlot transpiles correctly)
EXPORT DATA	Y	N (issue #418)	N (planned P3)
LOAD DATA	Y	N	N (SQLGlot ParseError)

Query Language

Feature	Production BQ	Go Emulator	Python Rewrite
SELECT * / EXCEPT / REPLACE	Y	Y	Y
SELECT AS STRUCT / VALUE	Y	Y	Y
INNER / LEFT / RIGHT / FULL / CROSS JOIN	Y	Y	Y
Correlated subqueries	Y	N	Y
Sequential JOINs	Y	N	Y
Non-recursive CTEs (WITH)	Y	Y	Y
Recursive CTEs (WITH RECURSIVE)	Y	N (issue #216)	Y (DuckDB native)
UNION / INTERSECT / EXCEPT [ALL]	Y	Y	Y
QUALIFY	Y	Y	Y (DuckDB native)
PIVOT / UNPIVOT	Y	Y	Y (DuckDB native)
TABLESAMPLE	Y	N	P (syntax differs; BERNOULLI→RESERVOIR semantic mismatch)
ORDER BY NULLS FIRST/LAST	Y	N	Y (DuckDB native)
UNNEST with WITH OFFSET	Y	Y	Y (→ WITH ORDINALITY)
Implicit UNNEST	Y	N	N
Pipe syntax (`\|>`)	Y	N	P (WHERE/SELECT/AGGREGATE/JOIN work; RENAME/CALL/SET/DROP/LIMIT crash)
Wildcard tables / `_TABLE_SUFFIX`	Y	Y	N (SQLGlot quotes `*` as identifier; planned P1)
Named parameters (`@param`)	Y	Y	Y (→ `$param`)
Table decorators (`@timestamp`)	Y (Legacy SQL)	N	N

Window Functions

Feature	Production BQ	Go Emulator	Python Rewrite
ROW_NUMBER / RANK / DENSE_RANK	Y	Y	Y
LEAD / LAG	Y	Y	Y
FIRST_VALUE / LAST_VALUE / NTH_VALUE	Y	Y	Y
NTH_VALUE(x, n FROM LAST)	Y	N	N (SQLGlot ParseError)
NTILE / CUME_DIST / PERCENT_RANK	Y	Y	Y
PERCENTILE_CONT / PERCENTILE_DISC	Y	P (issue #205, inconsistent results)	Y
Window over NULL partitions	Y	N (panic, issue #351)	Y

Scripting / Procedural Language

Feature	Production BQ	Go Emulator	Python Rewrite
DECLARE / SET	Y	N (issue #344)	P (single statements transpile; blocks truncated by SQLGlot — requires custom interpreter)
BEGIN…END	Y	Y	P (SQLGlot truncates after first statement)
IF / ELSEIF / ELSE / END IF	Y	Y (basic)	P (SQLGlot truncates block)
LOOP / WHILE / REPEAT / FOR…IN	Y	N	N (requires custom interpreter)
BREAK / CONTINUE	Y	N	N
RETURN	Y	N	N (SQLGlot ParseError)
RAISE	Y	N	N (SQLGlot ParseError)
CALL procedure	Y	N	N
EXECUTE IMMEDIATE	Y	N	N
BEGIN TRANSACTION / COMMIT	Y	Y	Y
ROLLBACK	Y	N	Y
BEGIN…EXCEPTION…END	Y	N	N

Data Types

Type	Production BQ	Go Emulator	Python Rewrite
INT64 / FLOAT64 / BOOL	Y	Y	Y
STRING	Y	Y	Y
BYTES	Y	Y	Y (→ BLOB)
NUMERIC / DECIMAL	Y	Y	Y
BIGNUMERIC (76 digits)	Y	Y	P (DuckDB DECIMAL max 38 digits)
DATE / TIME / DATETIME / TIMESTAMP	Y	Y (timezone bugs)	Y (DATETIME→TIMESTAMP, TIMESTAMP→TIMESTAMPTZ)
INTERVAL	Y	Y	Y
ARRAY	Y	P (blob encoding; NULL/nested bugs)	Y (→ LIST; must enforce no nested arrays)
STRUCT / RECORD	Y	P (blob encoding; nested query bugs)	Y (→ STRUCT; no REQUIRED/REPEATED mode enforcement)
JSON	Y	P (type works; function bugs)	Y
GEOGRAPHY	Y	N (3 of ~60 ST_* functions)	N (DuckDB spatial is planar, not geodesic)

Functions

Core Function Categories

Category	Production BQ	Go Emulator	Python Rewrite
Math functions (~30)	Y	Y	Y
String functions (~50)	Y	P (CONTAINS_SUBSTR, COLLATE, EDIT_DISTANCE missing)	Y (most transpile; TO_CODE_POINTS, NORMALIZE pass through)
Date/Time functions (~40)	Y	Y (edge-case bugs: DATE_TRUNC HOUR, DATETIME_DIFF off-by-one)	Y (TIMESTAMP(dt,tz) has reversed semantics)
JSON functions (~15)	Y	P (multiple bugs: #357, #379, #389, #428)	Y (LAX_* functions pass through)
Array functions (~15)	Y	P (crashes with length comparison, issue #410)	Y
Aggregate functions (~20)	Y	Y (COVAR_POP bug; MAX_BY/MIN_BY missing)	Y (ARRAY_AGG IGNORE NULLS silently dropped)
Approximate aggregates (~5)	Y	Y	P (APPROX_TOP_COUNT return type differs; APPROX_TOP_SUM missing)
HLL_COUNT.* sketch functions	Y	Y	N (no sketch serialization in DuckDB)
Window functions (~15)	Y	P (NULL partition crash; PERCENTILE_CONT inconsistency)	Y (NTH_VALUE FROM LAST is ParseError)
Hash/UUID (MD5, SHA*, FARM_FINGERPRINT)	Y	Y	Y

Specialized Function Categories

Category	Production BQ	Go Emulator	Python Rewrite
NET.* (10 functions)	Y	Y	N (pass through; planned P1 via Python UDFs)
Geography / ST_* (~60 functions)	Y	N (3 only)	N (DuckDB spatial is planar; planned P3)
SAFE_CAST	Y	Y	Y (→ TRY_CAST)
SAFE.* prefix (generic)	Y	P (named SAFE_DIVIDE etc. exist; generic prefix unclear)	N (no generic mechanism; planned P1)
SAFE_DIVIDE / SAFE_ADD / etc.	Y	Y	Y (SQLGlot handles these)
FORMAT() with %t/%T/%P	Y	Y	N (BQ-specific specifiers pass through)
ERROR()	Y	N	P (DuckDB has error() — casing may differ)
AEAD encryption (KEYS., AEAD.)	Y	N	N

Partitioning & Clustering

Feature	Production BQ	Go Emulator	Python Rewrite
Time-unit column partitioning	Y	N (issue #152)	P (DDL metadata stored; no physical partitioning)
Ingestion-time partitioning	Y	P (issue #317)	P (metadata + pseudocolumn injection)
Range partitioning	Y	N	P (metadata only)
`_PARTITIONTIME` / `_PARTITIONDATE` pseudocolumns	Y	N	P (planned P0, injected by emulator)
Partition pruning	Y	N	P (via DuckDB zonemap push-down)
Partition expiration	Y	N	P (application-layer TTL)
Required partition filter	Y	N	P (application-layer enforcement)
CLUSTER BY (DDL)	Y	N (bug, issue #373)	P (DDL accepted, metadata stored)
Cluster pruning	Y	N	N (DuckDB has no user-declared clustering)

INFORMATION_SCHEMA

View	Production BQ	Go Emulator	Python Rewrite
TABLES	Y	P (basic, limited schema)	P (planned P0; synthesize from catalog)
COLUMNS	Y	P (basic)	P (planned P0; synthesize)
SCHEMATA	Y	P	P (planned P0)
PARTITIONS	Y	N	P (planned P0; from partition metadata)
ROUTINES / PARAMETERS	Y	N	P (planned P1)
TABLE_STORAGE	Y	N	P (planned P2)
JOBS / JOBS_BY_USER	Y	N	P (planned P2; from job log)
VIEWS	Y	N	P (planned P1)
OBJECT_PRIVILEGES	Y	N	N (stub)
SEARCH_INDEXES / VECTOR_INDEXES	Y	N	N (stub)
RESERVATIONS / BI_CAPACITIES	Y	N	N (not applicable)
STREAMING_TIMELINE	Y	N	N (not applicable)

User-Defined Functions

Feature	Production BQ	Go Emulator	Python Rewrite
SQL scalar UDFs	Y	Y	Y (→ CREATE MACRO)
SQL table-valued functions	Y	N	P (→ CREATE MACRO … AS TABLE)
JavaScript UDFs	Y	P (basic cases; issue #337)	N (cannot execute JS)
Python UDFs	N (remote functions only)	N	Y (via DuckDB Python API)
User-defined aggregates (UDAFs)	Y	N	N
Remote functions	Y	N	N
Persistent UDFs (stored in dataset)	Y	Y	Y (DuckDB catalog)
Temporary UDFs	Y	Y	Y

BigQuery ML

Feature	Production BQ	Go Emulator	Python Rewrite
CREATE MODEL	Y	N	N (SQLGlot drops OPTIONS)
ML.PREDICT / ML.EVALUATE	Y	N	N (SQLGlot ParseError)
ML.GENERATE_TEXT	Y	N	N
AI.FORECAST	Y	N	N (SQLGlot ParseError)

REST API

Endpoint	Production BQ	Go Emulator	Python Rewrite
datasets.* (CRUD)	Y	Y	Y (planned)
tables.* (CRUD)	Y	Y	Y (planned)
tabledata.insertAll (streaming)	Y	Y	Y (planned)
tabledata.list	Y	Y	Y (planned)
jobs.query (synchronous)	Y	Y	Y (planned)
jobs.insert (async)	Y	Y	Y (planned)
jobs.get / list / cancel	Y	Y	Y (planned)
projects.list	Y	Y	Y (planned)
routines.* (CRUD)	Y	Y	Y (planned)
models.* (metadata only)	Y	Y (stub)	N (stub)
IAM (getIamPolicy, etc.)	Y	N (stub)	N (stub)
Transfer API	Y	N	N
Reservation API	Y	N	N
Connection API	Y	N	N

gRPC Storage API

Feature	Production BQ	Go Emulator	Python Rewrite
Read API (CreateReadSession)	Y	P (encoding bugs with arrays, nullable fields; issue #409)	Y (planned Phase 4)
Avro format reads	Y	P (issue #398, schema bytes in data)	Y (planned)
Arrow format reads	Y	P	Y (DuckDB native Arrow)
Write API (default stream)	Y	N (issue #246)	Y (planned Phase 4)
Write API (COMMITTED stream)	Y	N (issue #247)	Y (planned)
Write API (PENDING stream)	Y	P (issue #342, stream not found)	Y (planned)
BatchCommitWriteStreams	Y	N (issue #380, panic)	Y (planned)
SSL/TLS on gRPC	Y	N (issue #259)	Y (planned)

Advanced Features

Feature	Production BQ	Go Emulator	Python Rewrite
Materialized Views	Y	N	N (planned P2)
External Tables	Y	N	N (planned P3)
Table Snapshots / Clones	Y	N	N (planned P3)
FOR SYSTEM_TIME AS OF (time travel)	Y	N	N (planned P3)
Stored Procedures	Y	N	N (planned P1)
Row-level access policies	Y	N	N (stub)
Column-level security / policy tags	Y	N	N (stub)
Search indexes / SEARCH()	Y	N	N (stub)
Differential privacy aggregates	Y	N	N
BI Engine acceleration	Y	N	— (DuckDB is in-memory)
GCS integration (load/extract)	Y	P (CSV/JSON only)	P (planned; Parquet/CSV/JSON)

Summary Scorecard

Category	Go Emulator	Python Rewrite	Winner
ARM64 / Apple Silicon	N	Y	Python
DDL (basic)	Y	Y	Tie
DDL (ALTER TABLE)	N	Y	Python
DDL (partitioning/clustering)	N	P (metadata)	Python
DML (INSERT/UPDATE/DELETE)	P (UPDATE joins broken)	Y	Python
DML (MERGE)	P (buggy)	Y	Python
Core query language	Y	Y	Tie
Correlated subqueries	N	Y	Python
Recursive CTEs	N	Y	Python
Window functions	P (NULL crash)	Y	Python
Scripting	N (~0%)	P (requires interpreter)	Python
INFORMATION_SCHEMA	P (minimal)	P (synthesized, more planned)	Python
Math/String/Date functions	Y	Y	Tie
JSON functions	P (multiple bugs)	Y	Python
Array/Struct operations	P (encoding bugs)	Y	Python
Geography / ST_*	N (3 functions)	N (wrong model)	Tie (both bad)
NET. functions*	Y	N (planned)	Go
HLL_COUNT. sketches*	Y	N	Go
APPROX_ aggregates*	Y	P	Go
Wildcard tables / _TABLE_SUFFIX	Y	N (planned)	Go
JavaScript UDFs	P	N	Go
SAFE. prefix*	P	N (planned)	Go
REST API	Y (full)	Y (planned)	Tie
gRPC Storage Read API	P (encoding bugs)	Y (planned, Arrow native)	Python
gRPC Storage Write API	N (broken)	Y (planned)	Python
Type correctness (ARRAY/STRUCT/JSON)	P (SQLite blob encoding)	Y (DuckDB native columnar)	Python
Semantic correctness	P (many edge-case bugs)	P (TIMESTAMP tz reversed, IGNORE NULLS)	Tie (different bugs)

Score Summary

	Go Emulator	Python Rewrite
Categories where it wins	5 (NET, HLL, APPROX, wildcards, JS UDFs)	16 (ARM64, ALTER, MERGE, CTEs, correlated, etc.)
Categories tied	7	7
Categories where it loses	16	5

Key Takeaway

The Go emulator has a working REST API and covers some niche function categories (NET, HLL sketches, wildcards) that the Python rewrite will need to build. However, it has fundamental structural limitations — x86-64 only, SQLite blob encoding causing type bugs, broken MERGE/UPDATE, no ALTER TABLE, no partitioning, no scripting, broken gRPC Write API.

The Python rewrite gains significant ground on SQL correctness (DuckDB’s native columnar types vs SQLite blob encoding), modern SQL features (recursive CTEs, correlated subqueries), and ARM64 support. Its main gaps are features that need custom emulator-layer implementation: scripting interpreter, INFORMATION_SCHEMA synthesis, wildcard tables, SAFE.* prefix, and NET.* functions.

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