---------------------------------------------------------------- * ExecMaterial * * As long as we are at the end of the data collected in the tuplestore, * we collect one new row from the subplan on each call, and stash it * aside in the tuplestore before returning it. The tuplestore is * only read if we are asked to scan backwards, rescan, or mark/restore. * * ----------------------
| 46 | * ---------------------------------------------------------------- |
| 47 | */ |
| 48 | static TupleTableSlot * /* result tuple from subplan */ |
| 49 | ExecMaterial(PlanState *pstate) |
| 50 | { |
| 51 | MaterialState *node = castNode(MaterialState, pstate); |
| 52 | EState *estate; |
| 53 | ScanDirection dir; |
| 54 | bool forward; |
| 55 | Tuplestorestate *tuplestorestate; |
| 56 | bool eof_tuplestore; |
| 57 | TupleTableSlot *slot; |
| 58 | |
| 59 | CHECK_FOR_INTERRUPTS(); |
| 60 | |
| 61 | /* |
| 62 | * get state info from node |
| 63 | */ |
| 64 | estate = node->ss.ps.state; |
| 65 | dir = estate->es_direction; |
| 66 | forward = ScanDirectionIsForward(dir); |
| 67 | tuplestorestate = node->tuplestorestate; |
| 68 | |
| 69 | /* |
| 70 | * If first time through, and we need a tuplestore, initialize it. |
| 71 | */ |
| 72 | if (tuplestorestate == NULL && node->eflags != 0) |
| 73 | { |
| 74 | tuplestorestate = tuplestore_begin_heap(true, false, PlanStateOperatorMemKB(&node->ss.ps)); |
| 75 | tuplestore_set_eflags(tuplestorestate, node->eflags); |
| 76 | if (node->eflags & EXEC_FLAG_MARK) |
| 77 | { |
| 78 | /* |
| 79 | * Allocate a second read pointer to serve as the mark. We know it |
| 80 | * must have index 1, so needn't store that. |
| 81 | */ |
| 82 | int ptrno PG_USED_FOR_ASSERTS_ONLY; |
| 83 | |
| 84 | ptrno = tuplestore_alloc_read_pointer(tuplestorestate, |
| 85 | node->eflags); |
| 86 | Assert(ptrno == 1); |
| 87 | } |
| 88 | node->tuplestorestate = tuplestorestate; |
| 89 | |
| 90 | /* CDB: Offer extra info for EXPLAIN ANALYZE. */ |
| 91 | if (node->ss.ps.instrument && node->ss.ps.instrument->need_cdb) |
| 92 | { |
| 93 | /* Let the tuplestore share our Instrumentation object. */ |
| 94 | tuplestore_set_instrument(tuplestorestate, node->ss.ps.instrument); |
| 95 | |
| 96 | /* Request a callback at end of query. */ |
| 97 | node->ss.ps.cdbexplainfun = ExecMaterialExplainEnd; |
| 98 | } |
| 99 | |
| 100 | /* |
| 101 | * MPP: If requested, fetch all rows from subplan and put them |
| 102 | * in the tuplestore. This decouples a middle slice's receiving |
| 103 | * and sending Motion operators to neutralize a deadlock hazard. |
| 104 | * MPP TODO: Remove when a better solution is implemented. |
| 105 | * |
nothing calls this directly
no test coverage detected