diff options
Diffstat (limited to 'src/backend/executor/nodeMergeAppend.c')
| -rw-r--r-- | src/backend/executor/nodeMergeAppend.c | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/src/backend/executor/nodeMergeAppend.c b/src/backend/executor/nodeMergeAppend.c index e1b9b984a7a..081734e8172 100644 --- a/src/backend/executor/nodeMergeAppend.c +++ b/src/backend/executor/nodeMergeAppend.c @@ -66,6 +66,7 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags) { MergeAppendState *mergestate = makeNode(MergeAppendState); PlanState **mergeplanstates; + const TupleTableSlotOps *mergeops; Bitmapset *validsubplans; int nplans; int i, @@ -129,18 +130,6 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags) mergestate); /* - * Miscellaneous initialization - * - * MergeAppend nodes do have Result slots, which hold pointers to tuples, - * so we have to initialize them. FIXME - */ - ExecInitResultTupleSlotTL(&mergestate->ps, &TTSOpsVirtual); - - /* node returns slots from each of its subnodes, therefore not fixed */ - mergestate->ps.resultopsset = true; - mergestate->ps.resultopsfixed = false; - - /* * call ExecInitNode on each of the valid plans to be executed and save * the results into the mergeplanstates array. */ @@ -153,6 +142,31 @@ ExecInitMergeAppend(MergeAppend *node, EState *estate, int eflags) mergeplanstates[j++] = ExecInitNode(initNode, estate, eflags); } + /* + * Initialize MergeAppend's result tuple type and slot. If the child + * plans all produce the same fixed slot type, we can use that slot type; + * otherwise make a virtual slot. (Note that the result slot itself is + * used only to return a null tuple at end of execution; real tuples are + * returned to the caller in the children's own result slots. What we are + * doing here is allowing the parent plan node to optimize if the + * MergeAppend will return only one kind of slot.) + */ + mergeops = ExecGetCommonSlotOps(mergeplanstates, j); + if (mergeops != NULL) + { + ExecInitResultTupleSlotTL(&mergestate->ps, mergeops); + } + else + { + ExecInitResultTupleSlotTL(&mergestate->ps, &TTSOpsVirtual); + /* show that the output slot type is not fixed */ + mergestate->ps.resultopsset = true; + mergestate->ps.resultopsfixed = false; + } + + /* + * Miscellaneous initialization + */ mergestate->ps.ps_ProjInfo = NULL; /* |