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Diffstat (limited to 'src/backend/optimizer/plan/setrefs.c')
| -rw-r--r-- | src/backend/optimizer/plan/setrefs.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c index d10a98396c7..d91bc3b30de 100644 --- a/src/backend/optimizer/plan/setrefs.c +++ b/src/backend/optimizer/plan/setrefs.c @@ -1823,6 +1823,19 @@ set_dummy_tlist_references(Plan *plan, int rtoffset) Var *oldvar = (Var *) tle->expr; Var *newvar; + /* + * As in search_indexed_tlist_for_non_var(), we prefer to keep Consts + * as Consts, not Vars referencing Consts. Here, there's no speed + * advantage to be had, but it makes EXPLAIN output look cleaner, and + * again it avoids confusing the executor. + */ + if (IsA(oldvar, Const)) + { + /* just reuse the existing TLE node */ + output_targetlist = lappend(output_targetlist, tle); + continue; + } + newvar = makeVar(OUTER_VAR, tle->resno, exprType((Node *) oldvar), @@ -2010,6 +2023,16 @@ search_indexed_tlist_for_non_var(Node *node, { TargetEntry *tle; + /* + * If it's a simple Const, replacing it with a Var is silly, even if there + * happens to be an identical Const below; a Var is more expensive to + * execute than a Const. What's more, replacing it could confuse some + * places in the executor that expect to see simple Consts for, eg, + * dropped columns. + */ + if (IsA(node, Const)) + return NULL; + tle = tlist_member(node, itlist->tlist); if (tle) { |