org.eigenbase.sql
Class SqlExplain

java.lang.Object
  org.eigenbase.sql.SqlNode
      org.eigenbase.sql.SqlCall
          org.eigenbase.sql.SqlExplain

All Implemented Interfaces:

Cloneable

public class SqlExplain
extends SqlCall

A SqlExplain is a node of a parse tree which represents an EXPLAIN PLAN statement.

Nested Class Summary

static class

SqlExplain.Depth The level of abstraction with which to display the plan.

Field Summary

static int	AS_XML_OPERAND
static int	DEPTH_OPERAND
static int	DETAIL_LEVEL_OPERAND
static int	EXPLICANDUM_OPERAND
private int	nDynamicParams
static int	OPERAND_COUNT

Fields inherited from class org.eigenbase.sql.SqlCall

operands

Fields inherited from class org.eigenbase.sql.SqlNode

emptyArray

Constructor Summary

SqlExplain(SqlSpecialOperator operator, SqlNode explicandum, SqlLiteral detailLevel, SqlLiteral depth, SqlLiteral asXml, int nDynamicParams, SqlParserPos pos)

Method Summary

SqlExplain.Depth	getDepth() Returns the level of abstraction at which this plan should be displayed.
SqlExplainLevel	getDetailLevel()
int	getDynamicParamCount()
SqlNode	getExplicandum()
boolean	isXml() Returns whether result is to be in XML format.
void	unparse(SqlWriter writer, int leftPrec, int rightPrec) Writes a SQL representation of this node to a writer.
boolean	withImplementation()
boolean	withType()

Methods inherited from class org.eigenbase.sql.SqlCall

accept, clone, equalsDeep, findValidOptions, getCallSignature, getFunctionQuantifier, getKind, getMonotonicity, getOperands, getOperator, isA, isCountStar, isExpanded, isName, setOperand, setOperator, validate

Methods inherited from class org.eigenbase.sql.SqlNode

clone, cloneArray, equalDeep, getParserPosition, toSqlString, toSqlString, toString, validateExpr

Methods inherited from class java.lang.Object

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

Field Detail

EXPLICANDUM_OPERAND

public static final int EXPLICANDUM_OPERAND

See Also:

Constant Field Values

DETAIL_LEVEL_OPERAND

public static final int DETAIL_LEVEL_OPERAND

See Also:

Constant Field Values

DEPTH_OPERAND

public static final int DEPTH_OPERAND

See Also:

Constant Field Values

AS_XML_OPERAND

public static final int AS_XML_OPERAND

See Also:

Constant Field Values

OPERAND_COUNT

public static final int OPERAND_COUNT

See Also:

Constant Field Values

nDynamicParams

private final int nDynamicParams

Constructor Detail

SqlExplain

public SqlExplain(SqlSpecialOperator operator,
                  SqlNode explicandum,
                  SqlLiteral detailLevel,
                  SqlLiteral depth,
                  SqlLiteral asXml,
                  int nDynamicParams,
                  SqlParserPos pos)

Method Detail

getExplicandum

public SqlNode getExplicandum()

Returns:

the underlying SQL statement to be explained

getDetailLevel

public SqlExplainLevel getDetailLevel()

Returns:

detail level to be generated

getDepth

public SqlExplain.Depth getDepth()

Returns the level of abstraction at which this plan should be displayed.

getDynamicParamCount

public int getDynamicParamCount()

Returns:

the number of dynamic parameters in the statement

withImplementation

public boolean withImplementation()

Returns:

whether physical plan implementation should be returned

withType

public boolean withType()

Returns:

whether type should be returned

isXml

public boolean isXml()

Returns whether result is to be in XML format.

unparse

public void unparse(SqlWriter writer,
                    int leftPrec,
                    int rightPrec)

Description copied from class: SqlNode

Writes a SQL representation of this node to a writer.

The leftPrec and rightPrec parameters give us enough context to decide whether we need to enclose the expression in parentheses. For example, we need parentheses around "2 + 3" if preceded by "5 *". This is because the precedence of the "*" operator is greater than the precedence of the "+" operator.

The algorithm handles left- and right-associative operators by giving them slightly different left- and right-precedence.

If SqlWriter.isAlwaysUseParentheses() is true, we use parentheses even when they are not required by the precedence rules.

For the details of this algorithm, see SqlCall.unparse(org.eigenbase.sql.SqlWriter, int, int).

Overrides:

unparse in class SqlCall

Parameters:

writer - Target writer

leftPrec - The precedence of the SqlNode immediately preceding this node in a depth-first scan of the parse tree

rightPrec - The precedence of the SqlNode immediately