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https://issues.apache.org/jira/browse/IGNITE-25369?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Evgeny Stanilovsky reassigned IGNITE-25369:
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Assignee: Evgeny Stanilovsky
> Sql. Introduce EXPLAIN MAPPING FOR command
> ------------------------------------------
>
> Key: IGNITE-25369
> URL: https://issues.apache.org/jira/browse/IGNITE-25369
> Project: Ignite
> Issue Type: Improvement
> Components: sql ai3
> Reporter: Konstantin Orlov
> Assignee: Evgeny Stanilovsky
> Priority: Major
> Labels: ignite-3
>
> Apache Ignite is distributed system. It has an ability to have several copies
> of the data named replicas. Therefore, to execute a query, original plan is
> split on number of fragments, and every fragment is mapped on subset of
> nodes. It would be beneficial to provide an insight on which nodes will be
> used to execute which part of the query.
> For this, let's introduce to command {{EXPLAIN MAPPING FOR <queryOrDml>}}.
> Below is suggested output of the command:
> {code}
> EXPLAIN MAPPING FOR SELECT
> U.UserName, P.ProductName, R.ReviewText, R.Rating
> FROM Users U, Reviews R, Products P
> WHERE U.UserID = R.UserID
> AND R.ProductID = P.ProductID
> AND P.ProductName = 'Product_' || ?::varchar;
> Fragment#0 root
> executionNodes: [ijot_n_3344]
> plan:
> Project
> fields: [USERNAME, PRODUCTNAME, REVIEWTEXT, RATING]
> exprs: [USERNAME, PRODUCTNAME, REVIEWTEXT, RATING]
> est: (rows=1)
> HashJoin
> condition: =(USERID0, USERID)
> joinType: inner
> est: (rows=1)
> HashJoin
> condition: =(PRODUCTID, PRODUCTID0)
> joinType: inner
> est: (rows=1)
> Receiver
> rowType: RecordType(INTEGER PRODUCTID, INTEGER USERID,
> VARCHAR(65536) REVIEWTEXT, INTEGER RATING)
> exchangeId: 1
> sourceFragmentId: 1
> est: (rows=1)
> Receiver
> rowType: RecordType(INTEGER PRODUCTID, VARCHAR(100) PRODUCTNAME)
> exchangeId: 2
> sourceFragmentId: 2
> est: (rows=1)
> Receiver
> rowType: RecordType(INTEGER USERID, VARCHAR(100) USERNAME)
> exchangeId: 3
> sourceFragmentId: 3
> est: (rows=1)
> Fragment#1
> targetFragment: 0
> executionNodes: [ijot_n_3344, ijot_n_3345, ijot_n_3346]
> plan:
> Sender
> exchangeId: 1
> targetFragmentId: 0
> distribution: single
> est: (rows=50000)
> TableScan
> table: PUBLIC.REVIEWS
> fields: [PRODUCTID, USERID, REVIEWTEXT, RATING]
> sourceId: 6
> est: (rows=50000)
> Fragment#2
> targetFragment: 0
> executionNodes: [ijot_n_3344, ijot_n_3345, ijot_n_3346]
> plan:
> Sender
> exchangeId: 2
> targetFragmentId: 0
> distribution: single
> est: (rows=1665)
> TableScan
> table: PUBLIC.PRODUCTS
> filters: =(PRODUCTNAME, ||(_UTF-8'Product_', CAST(?0):VARCHAR CHARACTER
> SET "UTF-8"))
> fields: [PRODUCTID, PRODUCTNAME]
> sourceId: 5
> est: (rows=1665)
> Fragment#3
> targetFragment: 0
> executionNodes: [ijot_n_3344, ijot_n_3345, ijot_n_3346]
> plan:
> Sender
> exchangeId: 3
> targetFragmentId: 0
> distribution: single
> est: (rows=10000)
> TableScan
> table: PUBLIC.USERS
> fields: [USERID, USERNAME]
> sourceId: 4
> est: (rows=10000)
> {code}
> h3. Implementation Notes
> As a first step, it worth to reuse
> {{org.apache.ignite.internal.sql.engine.exec.mapping.FragmentPrinter}} as is,
> and adjust output in follow up ticket (IGNITE-25413).
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