org.vanilladb.core.query.algebra

Interface Plan

All Known Implementing Classes:

AbstractJoinPlan, ExplainPlan, GroupByPlan, HashJoinPlan, IndexJoinPlan, IndexSelectPlan, MaterializePlan, MergeJoinPlan, MultiBufferProductPlan, ProductPlan, ProjectPlan, ReduceRecordsPlan, SelectPlan, SortPlan, TablePlan

public interface Plan

The interface implemented by each query plan. There is a Plan class for each relational algebra operator.

Method Summary

Modifier and Type	Method and Description
long	blocksAccessed() Returns an estimate of the number of block accesses that will occur when the scan is read to completion.
Histogram	histogram() Returns the histogram that approximates the join distribution of the field values of query results.
Scan	open() Opens a scan corresponding to this plan.
long	recordsOutput() Returns an estimate of the number of records in the query's output table.
Schema	schema() Returns the schema of the query.

Method Detail

open

Scan open()

Opens a scan corresponding to this plan. The scan will be positioned before its first record.

Returns:

a scan

blocksAccessed

long blocksAccessed()

Returns an estimate of the number of block accesses that will occur when the scan is read to completion.

Returns:

the estimated number of block accesses

schema

Schema schema()

Returns the schema of the query.

Returns:

the query's schema

histogram

Histogram histogram()

Returns the histogram that approximates the join distribution of the field values of query results.

Returns:

the histogram

recordsOutput

long recordsOutput()

Returns an estimate of the number of records in the query's output table.

Returns:

the estimated number of output records