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Julian Hyde commented on CALCITE-3390: -------------------------------------- Yes, ITEM should be declared as "strong", in the sense that {{x[y]}} is null if {{x}} is null. But we don't have "only if"; I don't recall whether we need "only if" to safely push through outer joins. > ITEM expression does not get pushed to the right input of left-outer-join > ------------------------------------------------------------------------- > > Key: CALCITE-3390 > URL: https://issues.apache.org/jira/browse/CALCITE-3390 > Project: Calcite > Issue Type: Bug > Components: core > Affects Versions: 1.21.0 > Reporter: Aman Sinha > Assignee: Aman Sinha > Priority: Major > > In the following query, the ITEM expression above the Left Outer Join does > not get pushed to the right input (null-preserving input) of the join whereas > it should since ITEM does not change the nullability. > {noformat} > explain plan without implementation for select tt7.columns[0], tt8.columns[0] > as x from tt7 left outer join tt8 on tt7.columns[0] = tt8.columns[0]; > DrillScreenRel > DrillProjectRel(EXPR$0=[$1], x=[ITEM($2, 0)]) > DrillJoinRel(condition=[=($0, $3)], joinType=[left]) > DrillProjectRel($f2=[ITEM($0, 0)], ITEM=[ITEM($0, 0)]) > DrillScanRel(table=[[dfs, tmp, tt7]], groupscan=[EasyGroupScan > [selectionRoot=file:/tmp/tt7, numFiles=1, columns=[`columns`[0]], > files=[file:/tmp/tt7/0_0_0.csv]]]) > DrillProjectRel(columns=[$0], $f2=[ITEM($0, 0)]) > DrillScanRel(table=[[dfs, tmp, tt8]], groupscan=[EasyGroupScan > [selectionRoot=file:/tmp/tt8, numFiles=1, columns=[`columns`, `columns`[0]], > files=[file:/tmp/tt8/0_0_0.csv]]]) > {noformat} > From what I can tell, the change in behavior occurred with CALCITE-1753; > before that the ITEM was pushed on both sides of the Left Outer Join. -- This message was sent by Atlassian Jira (v8.3.4#803005)