Google BigQuery Keyword Compatibility Reference

Generated for GSP Java version 4.1.0.8 on 2026-03-15

This page was generated using hybrid static extraction from parser source files combined with runtime validation against the actual GSP parser. Re-run the extraction script after parser updates to keep this page current.

Keyword-as-Column-Name Support

As of version 4.1.0.8, the GSP Google BigQuery parser includes a lexer lookahead mechanism that allows 26 vendor-unreserved keywords to be used as unquoted column names in SELECT statements.

The lookahead pre-scans the token list before parsing and converts context-specific keywords to identifiers when they appear in column-name position:

• After: SELECT, ,, DISTINCT, or ALL
• Before: FROM, AS, WHERE, GROUP, ORDER, HAVING, LIMIT, UNION, INTERSECT, EXCEPT, INTO, ,, ), or ;

-- Works: keyword as column name
SELECT approx_quantiles FROM t;

-- Works: keyword as column name
SELECT approx_top_count FROM t;

-- Works: keyword as column name
SELECT approx_top_sum FROM t;

-- Original keyword syntax also still works

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Full Classification Overview

Out of 271 keywords recognized by the GSP Google BigQuery parser:

Classification	Count	Description
Allowed	243	Can be used as an unquoted column name in both canonical contexts
Context-specific	28	Fails as SELECT keyword FROM t but works as SELECT t.keyword FROM t
Blocked	0	Cannot be used as an unquoted column name in either context

Context-Specific Keywords (28)

These keywords fail when used as bare column names (SELECT keyword FROM t) but succeed when table-qualified (SELECT t.keyword FROM t).

Keyword	Reason
ALL	SELECT qualifier
APPROX_QUANTILES	Grammar keyword
APPROX_TOP_COUNT	Grammar keyword
APPROX_TOP_SUM	Grammar keyword
ARRAY	Type keyword
ARRAY_AGG	Grammar keyword
ARRAY_CONCAT_AGG	Grammar keyword
AS	Grammar keyword
BETWEEN	Operator keyword
CASE	Expression keyword
DISTINCT	SELECT qualifier
EXISTS	Operator keyword
FROM	Clause keyword
GENERATE_DATE_ARRAY	Grammar keyword
IF	Expression keyword
INSERT	Grammar keyword
INTERVAL	Type keyword
IS	Operator keyword
JOIN	JOIN keyword
LIKE	Operator keyword
NOT	Operator keyword
RIGHT	JOIN keyword
SAFE_CAST	Grammar keyword
STRING_AGG	Grammar keyword
STRUCT	Grammar keyword
TIMESTAMP_ADD	Grammar keyword
TIMESTAMP_SUB	Grammar keyword
WITH	Clause keyword

Workaround: Double-Quoted Identifiers

For any keyword that fails as an unquoted column name, you can use double-quoted identifiers:

-- Blocked or context-specific keyword as column name
SELECT "all" FROM t;

-- Or use table qualification for context-specific keywords
SELECT t.all FROM t;

Scope and Limitations

• Tested contexts: SELECT keyword FROM t and SELECT t.keyword FROM t. Other contexts (DDL column definitions, INSERT column lists, aliases) may behave differently.
• Version-specific: This report reflects GSP Java version 4.1.0.8.
• Case sensitivity: Keywords are case-insensitive. select, SELECT, and Select are all treated the same.

How to Report Discrepancies

If you encounter a keyword that behaves differently from what this page describes, please report it through your support channel. Include:

1. The exact SQL statement
2. The GSP parser version
3. Whether the same SQL works in Google BigQuery

Methodology

1. Static extraction: A Python script parses the lexer (.cod) and grammar (.y) source files to identify all 271 keywords and their grammar classifications.
2. Runtime validation: A Java test harness validates every classification against actual TGSqlParser runtime behavior.
3. JSON dataset: The authoritative data is stored in docs/generated/bigquery_keyword_compatibility.json.