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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2009-08-27 20:08:03 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2009-08-27 20:08:03 +0000 |
| commit | bb16dc49abd5b5af8f10781fb10f0439cd8431d6 (patch) | |
| tree | 8fc9b1f2ccdfcf12cc47e3f24054f1e0f1d55f38 /src/backend/parser/analyze.c | |
| parent | f065b17d9fa1915b6f6ba7a265ebe6f285706f50 (diff) | |
| download | postgresql-bb16dc49abd5b5af8f10781fb10f0439cd8431d6.tar.gz postgresql-bb16dc49abd5b5af8f10781fb10f0439cd8431d6.zip | |
Modify the definition of window-function PARTITION BY and ORDER BY clauses
so that their elements are always taken as simple expressions over the
query's input columns. It originally seemed like a good idea to make them
act exactly like GROUP BY and ORDER BY, right down to the SQL92-era behavior
of accepting output column names or numbers. However, that was not such a
great idea, for two reasons:
1. It permits circular references, as exhibited in bug #5018: the output
column could be the one containing the window function itself. (We actually
had a regression test case illustrating this, but nobody thought twice about
how confusing that would be.)
2. It doesn't seem like a good idea for, eg, "lead(foo) OVER (ORDER BY foo)"
to potentially use two completely different meanings for "foo".
Accordingly, narrow down the behavior of window clauses to use only the
SQL99-compliant interpretation that the expressions are simple expressions.
Diffstat (limited to 'src/backend/parser/analyze.c')
| -rw-r--r-- | src/backend/parser/analyze.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c index 97c560b3095..c441be220e2 100644 --- a/src/backend/parser/analyze.c +++ b/src/backend/parser/analyze.c @@ -17,7 +17,7 @@ * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.389 2009/06/11 14:48:59 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.390 2009/08/27 20:08:02 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -825,13 +825,14 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt) qry->sortClause = transformSortClause(pstate, stmt->sortClause, &qry->targetList, - true /* fix unknowns */ ); + true /* fix unknowns */, + false /* not window function */); qry->groupClause = transformGroupClause(pstate, stmt->groupClause, &qry->targetList, qry->sortClause, - false); + false /* not window function */); if (stmt->distinctClause == NIL) { @@ -1039,7 +1040,8 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt) qry->sortClause = transformSortClause(pstate, stmt->sortClause, &qry->targetList, - true /* fix unknowns */ ); + true /* fix unknowns */, + false /* not window function */); qry->limitOffset = transformLimitClause(pstate, stmt->limitOffset, "OFFSET"); @@ -1291,7 +1293,8 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt) qry->sortClause = transformSortClause(pstate, sortClause, &qry->targetList, - false /* no unknowns expected */ ); + false /* no unknowns expected */, + false /* not window function */); pstate->p_rtable = list_truncate(pstate->p_rtable, sv_rtable_length); pstate->p_relnamespace = sv_relnamespace; |