org.apache.calcite.sql.dialect

Class BigQuerySqlDialect

java.lang.Object

org.apache.calcite.sql.SqlDialect

org.apache.calcite.sql.dialect.BigQuerySqlDialect

public class BigQuerySqlDialect
extends SqlDialect

A SqlDialect implementation for Google BigQuery's "Standard SQL" dialect.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.calcite.sql.SqlDialect

SqlDialect.CalendarPolicy, SqlDialect.Context, SqlDialect.DatabaseProduct, SqlDialect.FakeUtil

Field Summary

Fields

Modifier and Type	Field and Description
static SqlDialect	DEFAULT
static SqlDialect.Context	DEFAULT_CONTEXT

Fields inherited from class org.apache.calcite.sql.SqlDialect

BUILT_IN_OPERATORS_LIST, EMPTY_CONTEXT, identifierEndQuoteString, identifierEscapedQuote, identifierQuoteString, literalEndQuoteString, literalEscapedQuote, literalQuoteString, LOGGER, nullCollation

Constructor Summary

Constructors

Constructor and Description
BigQuerySqlDialect(SqlDialect.Context context) Creates a BigQuerySqlDialect.

Method Summary

Modifier and Type	Method and Description
SqlParser.Config	configureParser(SqlParser.Config configBuilder) Copies settings from this dialect into a parser configuration.
@Nullable SqlNode	emulateNullDirection(SqlNode node, boolean nullsFirst, boolean desc) Returns the SqlNode for emulating the null direction for the given field or null if no emulation needs to be done.
@Nullable SqlNode	getCastSpec(RelDataType type) Returns SqlNode for type in "cast(column as type)", which might be different between databases by type name, precision etc.
protected boolean	identifierNeedsQuote(String val) Returns whether to quote an identifier.
boolean	supportsAggregateFunctionFilter() Returns whether this dialect supports the use of FILTER clauses for aggregate functions.
boolean	supportsAliasedValues() Returns whether the dialect supports VALUES in a sub-query with and an "AS t(column, ...)" values to define column names.
boolean	supportsApproxCountDistinct() Returns whether this dialect supports APPROX_COUNT_DISTINCT functions.
boolean	supportsImplicitTypeCoercion(RexCall call) Returns whether the dialect supports implicit type coercion.
boolean	supportsNestedAggregations() Returns whether the dialect supports nested aggregations, for instance SELECT SUM(SUM(1)) .
void	unparseCall(SqlWriter writer, SqlCall call, int leftPrec, int rightPrec)
void	unparseOffsetFetch(SqlWriter writer, @Nullable SqlNode offset, @Nullable SqlNode fetch) Converts an offset and fetch into SQL.
void	unparseSqlIntervalLiteral(SqlWriter writer, SqlIntervalLiteral literal, int leftPrec, int rightPrec) BigQuery interval syntax: INTERVAL int64 time_unit.
void	unparseSqlIntervalQualifier(SqlWriter writer, SqlIntervalQualifier qualifier, RelDataTypeSystem typeSystem) Converts an interval qualifier to a SQL string.

Methods inherited from class org.apache.calcite.sql.SqlDialect

allowsAs, configureParser, containsNonAscii, create, defaultNullDirection, emulateJoinTypeForCrossJoin, emulateNullDirectionWithIsNull, getCalendarPolicy, getConformance, getDatabaseProduct, getNullCollation, getProduct, getQuotedCasing, getQuoting, getSingleRowTableName, getTypeSystem, getUnquotedCasing, hasImplicitTableAlias, isCaseSensitive, quoteIdentifier, quoteIdentifier, quoteIdentifier, quoteStringLiteral, quoteStringLiteral, quoteStringLiteralUnicode, quoteTimestampLiteral, requiresAliasForFromItems, rewriteSingleValueExpr, supportsAggregateFunction, supportsCharSet, supportsDataType, supportsFunction, supportsGroupByLiteral, supportsGroupByWithCube, supportsGroupByWithRollup, supportsJoinType, supportsOffsetFetch, supportsWindowFunctions, unparseDateTimeLiteral, unparseFetchUsingAnsi, unparseFetchUsingLimit, unparseLimit, unparseOffset, unparseSqlDatetimeArithmetic, unparseTableScanHints, unparseTopN, unquoteStringLiteral

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_CONTEXT

public static final SqlDialect.Context DEFAULT_CONTEXT

DEFAULT

public static final SqlDialect DEFAULT

Constructor Detail

BigQuerySqlDialect

public BigQuerySqlDialect(SqlDialect.Context context)

Creates a BigQuerySqlDialect.

Method Detail

identifierNeedsQuote

protected boolean identifierNeedsQuote(String val)

Description copied from class: SqlDialect

Returns whether to quote an identifier. By default, all identifiers are quoted.

Overrides:

identifierNeedsQuote in class SqlDialect

emulateNullDirection

public @Nullable SqlNode emulateNullDirection(SqlNode node,
                                              boolean nullsFirst,
                                              boolean desc)

Description copied from class: SqlDialect

Returns the SqlNode for emulating the null direction for the given field or null if no emulation needs to be done.

Overrides:

emulateNullDirection in class SqlDialect

Parameters:

node - The SqlNode representing the expression

nullsFirst - Whether nulls should come first

desc - Whether the sort direction is RelFieldCollation.Direction#DESCENDING or RelFieldCollation.Direction#STRICTLY_DESCENDING

Returns:

A SqlNode for null direction emulation or null if not required

supportsImplicitTypeCoercion

public boolean supportsImplicitTypeCoercion(RexCall call)

Description copied from class: SqlDialect

Returns whether the dialect supports implicit type coercion.

Most of the sql dialects support implicit type coercion, so we make this method default return true. For instance, "cast('10' as integer) > 5" can be simplified to "'10' > 5" if the dialect supports implicit type coercion for VARCHAR and INTEGER comparison.

For sql dialect that does not support implicit type coercion, such as the BigQuery, we can not convert '10' into INT64 implicitly.

Now this method is used for some auxiliary decision when translating some RexCalls, see SqlImplementor#stripCastFromString for details.

Overrides:

supportsImplicitTypeCoercion in class SqlDialect

Parameters:

call - the call to make decision

supportsApproxCountDistinct

public boolean supportsApproxCountDistinct()

Description copied from class: SqlDialect

Returns whether this dialect supports APPROX_COUNT_DISTINCT functions.

Overrides:

supportsApproxCountDistinct in class SqlDialect

supportsNestedAggregations

public boolean supportsNestedAggregations()

Description copied from class: SqlDialect

Returns whether the dialect supports nested aggregations, for instance SELECT SUM(SUM(1)) .

Overrides:

supportsNestedAggregations in class SqlDialect

supportsAggregateFunctionFilter

public boolean supportsAggregateFunctionFilter()

Description copied from class: SqlDialect

Returns whether this dialect supports the use of FILTER clauses for aggregate functions. e.g. COUNT(*) FILTER (WHERE a = 2).

Overrides:

supportsAggregateFunctionFilter in class SqlDialect

configureParser

public SqlParser.Config configureParser(SqlParser.Config configBuilder)

Description copied from class: SqlDialect

Copies settings from this dialect into a parser configuration.

SqlDialect, SqlParser.Config and SqlConformance cover different aspects of the same thing - the dialect of SQL spoken by a database - and this method helps to bridge between them. (The aspects are, respectively, generating SQL to send to a source database, parsing SQL sent to Calcite, and validating queries sent to Calcite. It makes sense to keep them as separate interfaces because they are used by different modules.)

The settings copied may differ among dialects, and may change over time, but currently include the following:

• SqlDialect.getQuoting()
• SqlDialect.getQuotedCasing()
• SqlDialect.getUnquotedCasing()
• SqlDialect.isCaseSensitive()
• SqlDialect.getConformance()

Overrides:

configureParser in class SqlDialect

Parameters:

configBuilder - Parser configuration builder

Returns:

The configuration builder

unparseOffsetFetch

public void unparseOffsetFetch(SqlWriter writer,
                               @Nullable SqlNode offset,
                               @Nullable SqlNode fetch)

Description copied from class: SqlDialect

Converts an offset and fetch into SQL.

At least one of offset and fetch must be provided.

Common options:

• OFFSET offset ROWS FETCH NEXT fetch ROWS ONLY (ANSI standard SQL, Oracle, PostgreSQL, and the default)
• LIMIT fetch OFFSET offset (Apache Hive, MySQL, Redshift)

Overrides:

unparseOffsetFetch in class SqlDialect

Parameters:

writer - Writer

offset - Number of rows to skip before emitting, or null

fetch - Number of rows to fetch, or null

See Also:

SqlDialect.unparseFetchUsingAnsi(SqlWriter, SqlNode, SqlNode), SqlDialect.unparseFetchUsingLimit(SqlWriter, SqlNode, SqlNode)

supportsAliasedValues

public boolean supportsAliasedValues()

Description copied from class: SqlDialect

Returns whether the dialect supports VALUES in a sub-query with and an "AS t(column, ...)" values to define column names.

Currently, only Oracle does not. For this, we generate "SELECT v0 AS c0, v1 AS c1 ... UNION ALL ...". We may need to refactor this method when we support VALUES for other dialects.

Overrides:

supportsAliasedValues in class SqlDialect

unparseCall

public void unparseCall(SqlWriter writer,
                        SqlCall call,
                        int leftPrec,
                        int rightPrec)

Overrides:

unparseCall in class SqlDialect

unparseSqlIntervalLiteral

public void unparseSqlIntervalLiteral(SqlWriter writer,
                                      SqlIntervalLiteral literal,
                                      int leftPrec,
                                      int rightPrec)

BigQuery interval syntax: INTERVAL int64 time_unit.

Overrides:

unparseSqlIntervalLiteral in class SqlDialect

unparseSqlIntervalQualifier

public void unparseSqlIntervalQualifier(SqlWriter writer,
                                        SqlIntervalQualifier qualifier,
                                        RelDataTypeSystem typeSystem)

Description copied from class: SqlDialect

Converts an interval qualifier to a SQL string. The default implementation returns strings such as INTERVAL '1 2:3:4' DAY(4) TO SECOND(4).

Overrides:

unparseSqlIntervalQualifier in class SqlDialect

getCastSpec

public @Nullable SqlNode getCastSpec(RelDataType type)

Returns SqlNode for type in "cast(column as type)", which might be different between databases by type name, precision etc.

If this method returns null, the cast will be omitted. In the default implementation, this is the case for the NULL type, and therefore CAST(NULL AS <nulltype>) is rendered as NULL.

BigQuery data type reference: BigQuery Standard SQL Data Types.

Overrides:

getCastSpec in class SqlDialect