net.sf.saffron.rel.jdbc
Class JdbcQuery

java.lang.Object
  |
  +--net.sf.saffron.rel.SaffronRel
        |
        +--net.sf.saffron.rel.jdbc.JdbcQuery

public class JdbcQuery

extends SaffronRel

A JdbcQuery is a relational expression whose source is a SQL statement executed against a JDBC data source. It has result set calling convention.

Since:

2 August, 2002

Version:

$Id: //open/saffron/src/net/sf/saffron/rel/jdbc/JdbcQuery.java#5 $

Author:

jhyde

Field Summary

protected SaffronConnection	connection The expression which yields the connection object.
DataSource	dataSource
(package private) SqlDialect	dialect
(package private) String	queryString For debug.
(package private) SqlSelect	sql

Fields inherited from class net.sf.saffron.rel.SaffronRel

cluster, digest, id, rowType

Constructor Summary

JdbcQuery(VolcanoCluster cluster, SaffronType rowType, SaffronConnection connection, SqlDialect dialect, SqlSelect sql, DataSource dataSource)
Creates a JdbcQuery.

Method Summary

Object	clone()
PlanCost	computeSelfCost(SaffronPlanner planner) Returns the cost of this plan (not including children).
protected SaffronType	deriveRowType()
SaffronConnection	getConnection()
CallingConvention	getConvention() Returns a value from CallingConvention.
String	getQualifier()
Object	implement(RelImplementor implementor, int ordinal) Create a plan for this expression according to a calling convention.
void	onRegister(SaffronPlanner planner) This method is called just before the expression is registered.
static void	register(SaffronPlanner planner) Registers any special rules specific to this kind of relational expression.

Methods inherited from class net.sf.saffron.rel.SaffronRel

childrenAccept, computeDigest, explain, getChildExps, getCluster, getCorrelVariable, getId, getInput, getInputs, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRows, getRowType, getTable, getVariablesStopped, implementFieldAccess, isAccessTo, isDistinct, recomputeDigest, registerCorrelVariable, replaceInput, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Field Detail

dataSource

public final DataSource dataSource

connection

protected SaffronConnection connection

The expression which yields the connection object.

dialect

SqlDialect dialect

sql

SqlSelect sql

queryString

String queryString

For debug. Set on register.

Constructor Detail

JdbcQuery

public JdbcQuery(VolcanoCluster cluster,
                 SaffronType rowType,
                 SaffronConnection connection,
                 SqlDialect dialect,
                 SqlSelect sql,
                 DataSource dataSource)

Creates a JdbcQuery.

Parameters:

cluster - VolcanoCluster this relational expression belongs to

connection - a SaffronConnection; must also implement DataSource, because that's how we will acquire the JDBC connection; if you are generating code, the must have registered the connection with OJConnectionRegistry

sql - SQL parse tree, may be null, otherwise must be a SELECT statement

dataSource - Provides a JDBC connection to run this query against. If the query is implementing a JDBC table, then the connection's schema will implement JdbcSchema, and data source will typically be the same as calling JdbcSchema.getDataSource(net.sf.saffron.core.SaffronConnection). But non-JDBC schemas are also acceptable.

Pre-condition:

connection != null, sql == null || sql.isA(SqlNode.Kind.Select), dataSource != null

Method Detail

getConnection

public SaffronConnection getConnection()

getConvention

public CallingConvention getConvention()

Description copied from class: SaffronRel

Returns a value from CallingConvention.

Overrides:

getConvention in class SaffronRel

getQualifier

public String getQualifier()

Overrides:

getQualifier in class SaffronRel

clone

public Object clone()

Specified by:

clone in class SaffronRel

computeSelfCost

public PlanCost computeSelfCost(SaffronPlanner planner)

Description copied from class: SaffronRel

Returns the cost of this plan (not including children). The base implementation throws an error; derived classes should override.

Overrides:

computeSelfCost in class SaffronRel

onRegister

public void onRegister(SaffronPlanner planner)

Description copied from class: SaffronRel

This method is called just before the expression is registered. The implementation of this method must at least register all child expressions.

Overrides:

onRegister in class SaffronRel

register

public static void register(SaffronPlanner planner)

Description copied from class: SaffronRel

Registers any special rules specific to this kind of relational expression.

The planner calls this method this first time that it sees a relational expression of this class. The derived class should call SaffronPlanner.addRule(net.sf.saffron.opt.VolcanoRule) for each rule, and then call SaffronRel.register(net.sf.saffron.core.SaffronPlanner) on its base class.

implement

public Object implement(RelImplementor implementor,
                        int ordinal)

Description copied from class: SaffronRel

Create a plan for this expression according to a calling convention.

Overrides:

implement in class SaffronRel

Parameters:

implementor - implementor

ordinal - indicates our position in the pre-, in- and postfix walk over the tree; ordinal is -1 when called from the parent, and i when called from the i^th child.

deriveRowType

protected SaffronType deriveRowType()

Specified by:

deriveRowType in class SaffronRel