org.verdictdb.core.rewriter.query

Class AggQueryRewriter

java.lang.Object

org.verdictdb.core.rewriter.query.AggQueryRewriter

public class AggQueryRewriter
extends Object

AQP rewriter for partitioned tables. A sampling probability column must exist.

Author:

Yongjoo Park

Constructor Summary

Constructors

Constructor and Description
AggQueryRewriter(ScrambleMetaSet scrambleMeta)

Method Summary

Modifier and Type	Method and Description
List<org.apache.commons.lang3.tuple.Pair<AbstractRelation,AggblockMeta>>	rewrite(AbstractRelation relation) Current Limitations: 1.
List<org.apache.commons.lang3.tuple.Pair<AbstractRelation,AggblockMeta>>	rewriteAggregateQuery(AbstractRelation relation)
AbstractRelation	rewriteQueryRecursively(AbstractRelation relation, List<AbstractRelation> selectAllScrambled) Assuming the root is an aggregate query, rewriting performs the following.

Methods inherited from class java.lang.Object

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

Constructor Detail

AggQueryRewriter

public AggQueryRewriter(ScrambleMetaSet scrambleMeta)

Method Detail

rewrite

public List<org.apache.commons.lang3.tuple.Pair<AbstractRelation,AggblockMeta>> rewrite(AbstractRelation relation)
                                                                                 throws VerdictDBException

Current Limitations: 1. Only handles the query with a single aggregate (sub)query 2. Only handles the query that the first select list is the aggregate query.

Parameters:

relation -

Returns:

Throws:

VerdictDBException

rewriteAggregateQuery

public List<org.apache.commons.lang3.tuple.Pair<AbstractRelation,AggblockMeta>> rewriteAggregateQuery(AbstractRelation relation)
                                                                                               throws VerdictDBException

Throws:

VerdictDBException

rewriteQueryRecursively

public AbstractRelation rewriteQueryRecursively(AbstractRelation relation,
                                                List<AbstractRelation> selectAllScrambled)
                                         throws VerdictDBException

Assuming the root is an aggregate query, rewriting performs the following. 1. Recursively converts a select query (or a base table) into an alternative expression. 2. If a base table is not a scrambled table, it returns the same base table. 3. If a base table is a scrambled table, it performs: a. converts it into a select-star query (with a certain alias name). b. register the select-start query into the 'selectAllScrambled' list. c. register the information of the select-star query into 'scrambleMeta': (1) sid column (2) tier column 4. If a select query is not a scrambled table, it returns the same select query. 5. If a select query is a scrambled table, it performs: a. adds the following two columns to the select list and to 'scrambleMeta': (1) sid column (2) tier column

Parameters:

relation -

Returns:

Throws:

VerdictDBException