org.eigenbase.rel
Class TableAccessRel

java.lang.Object
  org.eigenbase.rel.AbstractRelNode
      org.eigenbase.rel.TableAccessRelBase
          org.eigenbase.rel.TableAccessRel

All Implemented Interfaces:

Cloneable, RelNode

public final class TableAccessRel
extends TableAccessRelBase

A TableAccessRel reads all the rows from a RelOptTable.

If the table is a net.sf.saffron.ext.JdbcTable, then this is literally possible. But for other kinds of tables, there may be many ways to read the data from the table. For some kinds of table, it may not even be possible to read all of the rows unless some narrowing constraint is applied.

In the example of the net.sf.saffron.ext.ReflectSchema schema,

select from fields

cannot be implemented, but

select from fields as f
 where f.getClass().getName().equals("java.lang.String")

can. It is the optimizer's responsibility to find these ways, by applying transformation rules.

Since:

10 November, 2001

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/TableAccessRel.java#12 $

Author:

jhyde

Field Summary

Fields inherited from class org.eigenbase.rel.TableAccessRelBase

connection, table

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, nextId, rowType, traits

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

TableAccessRel(RelOptCluster cluster, RelOptTable table, RelOptConnection connection)
Creates a TableAccessRel.

Method Summary

Methods inherited from class org.eigenbase.rel.TableAccessRelBase

clone, computeSelfCost, deriveRowType, explain, getCollationList, getConnection, getRows, getTable

Methods inherited from class org.eigenbase.rel.AbstractRelNode

childrenAccept, cloneTraits, collectVariablesSet, collectVariablesUsed, computeDigest, getChildExps, getCluster, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getInputs, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRowType, getTraits, getVariablesStopped, inheritTraitsFrom, isAccessTo, isDistinct, isValid, onRegister, recomputeDigest, register, registerCorrelVariable, replaceInput, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

TableAccessRel

public TableAccessRel(RelOptCluster cluster,
                      RelOptTable table,
                      RelOptConnection connection)

Creates a TableAccessRel.

Parameters:

cluster - Cluster

table - Table

connection - Connection