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https://issues.apache.org/jira/browse/CALCITE-7546?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated CALCITE-7546:
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Labels: pull-request-available (was: )
> NullPointerException in SqlToRelConverter for UNNEST(array) AS alias under
> conformance with allowAliasUnnestItems=true
> ----------------------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-7546
> URL: https://issues.apache.org/jira/browse/CALCITE-7546
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.40.0
> Environment: - Calcite: 1.40.0
> - JDK: Temurin 25+36-LTS
> - OS: macOS (darwin 23.3.0)
> - JUnit: 5
> Reporter: tnakama
> Priority: Major
> Labels: pull-request-available
>
>
> When SqlConformance#allowAliasUnnestItems() returns true (in stock Calcite
> this is only SqlConformanceEnum.PRESTO; user-defined conformances overriding
> this flag
> are also affected), a query of the form
> SELECT t FROM UNNEST(ARRAY[1, 2, 3]) AS t
> throws NullPointerException: fieldNames during SQL-to-Rel conversion.
> Root cause
>
> In SqlToRelConverter#convertFrom, the AS branch with operandCount() == 2
> (table alias only, no column list) delegates to convertUnnest with fieldNames
> == null.
> The allowAliasUnnestItems branch of convertUnnest then calls
> Objects.requireNonNull(fieldNames, "fieldNames") and throws.
> The bug is latent under the default conformance because
> allowAliasUnnestItems() is false there, so the offending branch is never
> entered. Adding an explicit
> column list (AS t(x)) also avoids the NPE because convertFrom then routes
> through the operandCount() == 3 branch that populates fieldNames.
> Reproducer
> ---
> package jp.co.plaid.mila.processing.sql.convert;
> import org.junit.jupiter.api.Test;
> import java.sql.Connection;
> import java.sql.DriverManager;
> import java.sql.SQLException;
> import java.sql.Statement;
> import java.util.Properties;
> class CalciteUnnestAliasNpeReproducerTest {
> @Test
> void unnestWithTableAliasOnly_throwsNpe_underPrestoConformance() throws
> SQLException {
> Properties info = new Properties();
> info.setProperty("conformance", "PRESTO");
> Connection conn = DriverManager.getConnection("jdbc:calcite:", info);
> Statement stmt = conn.createStatement();
> stmt.executeQuery("SELECT t FROM UNNEST(ARRAY[1, 2, 3]) AS t");
> }
> }
> ---
> Expected behavior
>
> UNNEST(array) AS alias under a conformance with allowAliasUnnestItems() ==
> true should either:
> - be treated as AS alias(alias) (single-column alias, matching common
> BigQuery/Presto-like semantics), or
> - produce a clear validation error rather than an internal NPE.
>
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