Package org.apache.calcite.sql.dialect

Class PrestoSqlDialect

java.lang.Object
org.apache.calcite.sql.SqlDialect
org.apache.calcite.sql.dialect.PrestoSqlDialect
public class PrestoSqlDialect extends SqlDialect
A SqlDialect implementation for the Presto database.

  • Field Details

  • Constructor Details

    • PrestoSqlDialect

      public PrestoSqlDialect(SqlDialect.Context context)
      Creates a PrestoSqlDialect.

  • Method Details

    • supportsApproxCountDistinct

      public boolean supportsApproxCountDistinct()
      Description copied from class: SqlDialect
      Returns whether this dialect supports APPROX_COUNT_DISTINCT functions.
      Overrides:
      supportsApproxCountDistinct in class SqlDialect

    • supportsCharSet

      public boolean supportsCharSet()
      Description copied from class: SqlDialect
      Returns whether the dialect supports character set names as part of a data type, for instance VARCHAR(30) CHARACTER SET `ISO-8859-1`.
      Overrides:
      supportsCharSet in class SqlDialect

    • requiresAliasForFromItems

      public boolean requiresAliasForFromItems()
      Description copied from class: SqlDialect
      Whether a sub-query in the FROM clause must have an alias.

      For example, in PostgreSQL, this query is legal:

      SELECT * FROM (SELECT * FROM Emp) As e

      but remove the alias e and it is not:

      SELECT * FROM (SELECT * FROM Emp)

      In Oracle, both queries are legal.

      Overrides:
      requiresAliasForFromItems in class SqlDialect

    • supportsTimestampPrecision

      public boolean supportsTimestampPrecision()
      Description copied from class: SqlDialect
      Returns whether this dialect supports TIMESTAMP with precision.
      Overrides:
      supportsTimestampPrecision in class SqlDialect

    • 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:

    • 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

    • 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

    • supportsAggregateFunction

      public boolean supportsAggregateFunction(SqlKind kind)
      Overrides:
      supportsAggregateFunction in class SqlDialect

    • supportsGroupByWithCube

      public boolean supportsGroupByWithCube()
      Description copied from class: SqlDialect
      Returns whether this dialect supports "WITH CUBE" in "GROUP BY" clause.
      Overrides:
      supportsGroupByWithCube 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

    • supportsGroupByWithRollup

      public boolean supportsGroupByWithRollup()
      Description copied from class: SqlDialect
      Returns whether this dialect supports "WITH ROLLUP" in the "GROUP BY" clause.

      For instance, in MySQL version 5,

      SELECT deptno, job, COUNT(*) AS c FROM emp GROUP BY deptno, job WITH ROLLUP

      is equivalent to standard SQL

      SELECT deptno, job, COUNT(*) AS c FROM emp GROUP BY ROLLUP(deptno, job) ORDER BY deptno, job

      The "WITH ROLLUP" clause was introduced in MySQL and is not standard SQL.

      See also SqlDialect.supportsAggregateFunction(SqlKind) applied to SqlKind.ROLLUP, which returns true in MySQL 8 and higher.

      Overrides:
      supportsGroupByWithRollup in class SqlDialect

    • getCalendarPolicy

      public SqlDialect.CalendarPolicy getCalendarPolicy()
      Overrides:
      getCalendarPolicy in class SqlDialect

    • getCastSpec

      public @Nullable SqlNode getCastSpec(RelDataType type)
      Description copied from class: SqlDialect
      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.

      Overrides:
      getCastSpec in class SqlDialect

    • unparseCall

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