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https://issues.apache.org/jira/browse/CALCITE-6846?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17928604#comment-17928604
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Silun Dong commented on CALCITE-6846:
-------------------------------------
Its printing form is similar to MultiJoin, but its actual function is
different. For example, the member variables are different (HyperEdge, EdgeMap,
etc.), and the member methods are different (the method of obtaining subgraph
neighbors, the method of determining the connectivity between subgraphs, etc.)
> Support basic dphyp join reorder algorithm
> ------------------------------------------
>
> Key: CALCITE-6846
> URL: https://issues.apache.org/jira/browse/CALCITE-6846
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Affects Versions: 1.38.0
> Reporter: Silun Dong
> Assignee: Silun Dong
> Priority: Major
> Labels: pull-request-available
>
> Supports the basic dphyp join reorder algorithm.
> For example :
> {code:java}
> SELECT
> i_item_id
> FROM store_sales, customer_demographics, date_dim, item, promotion
> WHERE ss_sold_date_sk = d_date_sk AND
> ss_item_sk = i_item_sk AND
> ss_cdemo_sk = cd_demo_sk AND
> ss_promo_sk = p_promo_sk {code}
> The plan tree after pushing down filter :
> {code:java}
> LogicalProject(i_item_id=[$61])
> LogicalJoin(condition=[=($7, $82)], joinType=[inner])
> LogicalJoin(condition=[=($1, $60)], joinType=[inner])
> LogicalJoin(condition=[=($22, $32)], joinType=[inner])
> LogicalJoin(condition=[=($3, $23)], joinType=[inner])
> LogicalTableScan(table=[[tpcds, store_sales]])
> LogicalTableScan(table=[[tpcds, customer_demographics]])
> LogicalTableScan(table=[[tpcds, date_dim]])
> LogicalTableScan(table=[[tpcds, item]])
> LogicalTableScan(table=[[tpcds, promotion]]){code}
> Convert Joins into one HyperGraph :
> {code:java}
> LogicalProject(i_item_id=[$61])
>
> HyperGraph(edges=[{0}——INNER——{1},{0}——INNER——{2},{0}——INNER——{3},{0}——INNER——{4}])
> LogicalTableScan(table=[[tpcds, store_sales]])
> LogicalTableScan(table=[[tpcds, customer_demographics]])
> LogicalTableScan(table=[[tpcds, date_dim]])
> LogicalTableScan(table=[[tpcds, item]])
> LogicalTableScan(table=[[tpcds, promotion]]) {code}
> After dphyp join reorder (with trimming fields and pushing down Project), the
> plan is :
> {code:java}
> LogicalProject(i_item_id=[$1])
> LogicalJoin(condition=[=($0, $2)], joinType=[inner])
> LogicalProject(ss_cdemo_sk=[$0], i_item_id=[$2])
> LogicalJoin(condition=[=($1, $3)], joinType=[inner])
> LogicalProject(ss_cdemo_sk=[$1], ss_sold_date_sk=[$2], i_item_id=[$4])
> LogicalJoin(condition=[=($0, $3)], joinType=[inner])
> LogicalProject(ss_item_sk=[$0], ss_cdemo_sk=[$1],
> ss_sold_date_sk=[$3])
> LogicalJoin(condition=[=($2, $4)], joinType=[inner])
> LogicalProject(ss_item_sk=[$1], ss_cdemo_sk=[$3],
> ss_promo_sk=[$7], ss_sold_date_sk=[$22])
> LogicalTableScan(table=[[tpcds, store_sales]])
> LogicalProject(p_promo_sk=[$0])
> LogicalTableScan(table=[[tpcds, promotion]])
> LogicalProject(i_item_sk=[$0], i_item_id=[$1])
> LogicalTableScan(table=[[tpcds, item]])
> LogicalProject(d_date_sk=[$0])
> LogicalTableScan(table=[[tpcds, date_dim]])
> LogicalProject(cd_demo_sk=[$0])
> LogicalTableScan(table=[[tpcds, customer_demographics]]) {code}
> The main enumeration process of dphyp will be implemented in pr. However, it
> only can process inner join for now and the simplification of hypergraph has
> not yet been implemented.
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