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Commit2f02d4a

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Allow extracting fields from a ROW() expression in more cases.
Teach get_expr_result_type() to manufacture a tuple descriptor directlyfrom a RowExpr node. If the RowExpr has type RECORD, this is the onlyway to get a tupdesc for its result, since even if the rowtype has beenblessed, we don't have its typmod available at this point. (If theRowExpr has some named composite type, we continue to let the existingcode handle it, since the RowExpr might well not have the correct columnnames embedded in it.)This fixes assorted corner cases illustrated by the added regressiontests.This is a back-patch of the v13-era commit8b7a0f1 into previousbranches. At the time I'd judged it not important enough to back-patch,but the upcoming fix for bug #18077 includes a test case that dependson this working correctly; and8b7a0f1 has now aged long enough tohave good confidence that it won't break anything.Discussion:https://postgr.es/m/10872.1572202006@sss.pgh.pa.usDiscussion:https://postgr.es/m/3607145.1694803130@sss.pgh.pa.us
1 parent50d44c1 commit2f02d4a

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3 files changed

+80
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lines changed

3 files changed

+80
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lines changed

‎src/backend/utils/fmgr/funcapi.c

Lines changed: 32 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -236,6 +236,38 @@ get_expr_result_type(Node *expr,
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NULL,
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resultTypeId,
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resultTupleDesc);
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elseif (expr&&IsA(expr,RowExpr)&&
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((RowExpr*)expr)->row_typeid==RECORDOID)
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{
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/* We can resolve the record type by generating the tupdesc directly */
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RowExpr*rexpr= (RowExpr*)expr;
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TupleDesctupdesc;
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AttrNumberi=1;
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ListCell*lcc,
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*lcn;
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tupdesc=CreateTemplateTupleDesc(list_length(rexpr->args));
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Assert(list_length(rexpr->args)==list_length(rexpr->colnames));
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forboth(lcc,rexpr->args,lcn,rexpr->colnames)
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{
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Node*col= (Node*)lfirst(lcc);
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char*colname=strVal(lfirst(lcn));
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TupleDescInitEntry(tupdesc,i,
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colname,
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exprType(col),
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exprTypmod(col),
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0);
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TupleDescInitEntryCollation(tupdesc,i,
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exprCollation(col));
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i++;
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}
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if (resultTypeId)
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*resultTypeId=rexpr->row_typeid;
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if (resultTupleDesc)
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*resultTupleDesc=BlessTupleDesc(tupdesc);
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returnTYPEFUNC_COMPOSITE;
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}
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else
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{
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/* handle as a generic expression; no chance to resolve RECORD */

‎src/test/regress/expected/rowtypes.out

Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -445,6 +445,45 @@ where i8 in (row(123,456)::int8_tbl, '(4567890123456789,123)');
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4567890123456789 | 123
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(2 rows)
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-- Check ability to select columns from an anonymous rowtype
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select (row(1, 2.0)).f1;
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f1
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----
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1
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(1 row)
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select (row(1, 2.0)).f2;
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f2
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-----
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2.0
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(1 row)
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select (row(1, 2.0)).nosuch; -- fail
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ERROR: could not identify column "nosuch" in record data type
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LINE 1: select (row(1, 2.0)).nosuch;
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^
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select (row(1, 2.0)).*;
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f1 | f2
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----+-----
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1 | 2.0
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(1 row)
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select (r).f1 from (select row(1, 2.0) as r) ss;
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f1
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----
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1
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(1 row)
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select (r).f3 from (select row(1, 2.0) as r) ss; -- fail
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ERROR: could not identify column "f3" in record data type
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LINE 1: select (r).f3 from (select row(1, 2.0) as r) ss;
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^
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select (r).* from (select row(1, 2.0) as r) ss;
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f1 | f2
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----+-----
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1 | 2.0
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(1 row)
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-- Check some corner cases involving empty rowtypes
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select ROW();
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row

‎src/test/regress/sql/rowtypes.sql

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -176,6 +176,15 @@ where i8 in (row(123,456)::int8_tbl, '(4567890123456789,123)');
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select*from int8_tbl i8
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where i8in (row(123,456)::int8_tbl,'(4567890123456789,123)');
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-- Check ability to select columns from an anonymous rowtype
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select (row(1,2.0)).f1;
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select (row(1,2.0)).f2;
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select (row(1,2.0)).nosuch;-- fail
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select (row(1,2.0)).*;
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select (r).f1from (select row(1,2.0)as r) ss;
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select (r).f3from (select row(1,2.0)as r) ss;-- fail
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select (r).*from (select row(1,2.0)as r) ss;
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-- Check some corner cases involving empty rowtypes
180189
select ROW();
181190
select ROW() ISNULL;

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