pack-priv Class IndexToBaseRowNode

Overrides org.apache.derby.impl.sql.compile.FromTable.acceptChildren.

Accept the visitor for all visitable children of this node.

Parameters

v:Visitor

the visitor

Annotations

@Override

Exceptions

StandardException:

on error

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.adjustForSortElimination.

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.adjustForSortElimination.

Notify the underlying result set tree that the optimizer has chosen to "eliminate" a sort. Sort elimination can happen as part of preprocessing (see esp. SelectNode.preprocess(...)) or it can happen if the optimizer chooses an access path that inherently returns the rows in the correct order (also known as a "sort avoidance" plan). In either case we drop the sort and rely on the underlying result set tree to return its rows in the correct order. For most types of ResultSetNodes we automatically get the rows in the correct order if the sort was eliminated. One exception to this rule, though, is the case of an IndexRowToBaseRowNode, for which we have to disable bulk fetching on the underlying base table. Otherwise the index scan could return rows out of order if the base table is updated while the scan is "in progress" (i.e. while the result set is open). In order to account for this (and potentially other, similar issues in the future) this method exists to notify the result set node that it is expected to return rows in the correct order. The result set can then take necessary action to satsify this requirement--such as disabling bulk fetch in the case of IndexRowToBaseRowNode. All of that said, any ResultSetNodes for which we could potentially eliminate sorts should override this method accordingly. So we don't ever expect to get here.

Annotations

@Override

See Also

ResultSetNode#adjustForSortElimination

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.adjustForSortElimination.

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.adjustForSortElimination.

Same goal as adjustForSortElimination above, but this version takes a RequiredRowOrdering to allow nodes to adjust based on the ORDER BY clause, if needed.

Annotations

@Override

See Also

ResultSetNode#adjustForSortElimination

Overrides org.apache.derby.impl.sql.compile.FromTable.decrementLevel.

Decrement (query block) level (0-based) for this FromTable. This is useful when flattening a subquery.

Parameters

decrement:int

The amount to decrement by.

Annotations

@Override

Overrides org.apache.derby.impl.sql.compile.QueryTreeNode.generate.

Generation of an IndexToBaseRowNode creates an IndexRowToBaseRowResultSet, which uses the RowLocation in the last column of an index row to get the row from the base conglomerate (heap).

Parameters

acb:ActivationClassBuilder

The ActivationClassBuilder for the class being built

mb:MethodBuilder

the method for the method to be built

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.getCostEstimate.

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.getCostEstimate.

Get the CostEstimate for this ResultSetNode.

Returns:CostEstimate

The CostEstimate for this ResultSetNode.

Annotations

@Override

Overrides org.apache.derby.impl.sql.compile.FromTable.getFinalCostEstimate.

Doc from org.apache.derby.impl.sql.compile.FromTable.getFinalCostEstimate.

Get the final CostEstimate for this FromTable.

Returns:CostEstimate

The final CostEstimate for this FromTable, which is the costEstimate of trulyTheBestAccessPath if there is one. If there's no trulyTheBestAccessPath for this node, then we just return the value stored in costEstimate as a default.

Annotations

@Override

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.isNotExists.

Return whether or not the underlying FBT is for NOT EXISTS.

Returns:boolean

Whether or not the underlying FBT is for NOT EXISTS.

Annotations

@Override

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.isOneRowResultSet.

Return whether or not the underlying ResultSet tree will return a single row, at most. This is important for join nodes where we can save the extra next on the right side if we know that it will return at most 1 row.

Returns:boolean

Whether or not the underlying ResultSet tree will return a single row.

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.isOrderedOn.

Return whether or not the underlying ResultSet tree is ordered on the specified columns. RESOLVE - This method currently only considers the outermost table of the query block.

Parameters

crs:ColumnReference[]

The specified ColumnReference[]

permuteOrdering:boolean

Whether or not the order of the CRs in the array can be permuted

fbtHolder:List<FromBaseTable>

List that is to be filled with the FromBaseTable

Returns:boolean

Whether the underlying ResultSet tree is ordered on the specified column.

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.updateTargetLockMode.

Get the lock mode for the target of an update statement (a delete or update). The update mode will always be row for CurrentOfNodes. It will be table if there is no where clause.

Returns:int

The lock mode

Annotations

@Override