diff options
Diffstat (limited to 'src/backend/commands')
| -rw-r--r-- | src/backend/commands/explain.c | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 8345bc0264b..207f86f1d39 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -147,6 +147,7 @@ static void show_buffer_usage(ExplainState *es, const BufferUsage *usage); static void show_wal_usage(ExplainState *es, const WalUsage *usage); static void show_memory_counters(ExplainState *es, const MemoryContextCounters *mem_counters); +static void show_result_replacement_info(Result *result, ExplainState *es); static void ExplainIndexScanDetails(Oid indexid, ScanDirection indexorderdir, ExplainState *es); static void ExplainScanTarget(Scan *plan, ExplainState *es); @@ -1229,6 +1230,10 @@ ExplainPreScanNode(PlanState *planstate, Bitmapset **rels_used) *rels_used = bms_add_members(*rels_used, ((MergeAppend *) plan)->apprelids); break; + case T_Result: + *rels_used = bms_add_members(*rels_used, + ((Result *) plan)->relids); + break; default: break; } @@ -2232,6 +2237,7 @@ ExplainNode(PlanState *planstate, List *ancestors, ancestors, es); break; case T_Result: + show_result_replacement_info(castNode(Result, plan), es); show_upper_qual((List *) ((Result *) plan)->resconstantqual, "One-Time Filter", planstate, ancestors, es); show_upper_qual(plan->qual, "Filter", planstate, ancestors, es); @@ -4751,6 +4757,102 @@ show_modifytable_info(ModifyTableState *mtstate, List *ancestors, } /* + * Explain what a "Result" node replaced. + */ +static void +show_result_replacement_info(Result *result, ExplainState *es) +{ + StringInfoData buf; + int nrels = 0; + int rti = -1; + bool found_non_result = false; + char *replacement_type = "???"; + + /* If the Result node has a subplan, it didn't replace anything. */ + if (result->plan.lefttree != NULL) + return; + + /* Gating result nodes should have a subplan, and we don't. */ + Assert(result->result_type != RESULT_TYPE_GATING); + + switch (result->result_type) + { + case RESULT_TYPE_GATING: + replacement_type = "Gating"; + break; + case RESULT_TYPE_SCAN: + replacement_type = "Scan"; + break; + case RESULT_TYPE_JOIN: + replacement_type = "Join"; + break; + case RESULT_TYPE_UPPER: + /* a small white lie */ + replacement_type = "Aggregate"; + break; + case RESULT_TYPE_MINMAX: + replacement_type = "MinMaxAggregate"; + break; + } + + /* + * Build up a comma-separated list of user-facing names for the range + * table entries in the relids set. + */ + initStringInfo(&buf); + while ((rti = bms_next_member(result->relids, rti)) >= 0) + { + RangeTblEntry *rte = rt_fetch(rti, es->rtable); + char *refname; + + /* + * add_outer_joins_to_relids will add join RTIs to the relids set of a + * join; if that join is then replaced with a Result node, we may see + * such RTIs here. But we want to completely ignore those here, + * because "a LEFT JOIN b ON whatever" is a join between a and b, not + * a join between a, b, and an unnamed join. + */ + if (rte->rtekind == RTE_JOIN) + continue; + + /* Count the number of rels that aren't ignored completely. */ + ++nrels; + + /* Work out what reference name to use and add it to the string. */ + refname = (char *) list_nth(es->rtable_names, rti - 1); + if (refname == NULL) + refname = rte->eref->aliasname; + if (buf.len > 0) + appendStringInfoString(&buf, ", "); + appendStringInfoString(&buf, refname); + + /* Keep track of whether we see anything other than RTE_RESULT. */ + if (rte->rtekind != RTE_RESULT) + found_non_result = true; + } + + /* + * If this Result node is because of a single RTE that is RTE_RESULT, it + * is not really replacing anything at all, because there's no other + * method for implementing a scan of such an RTE, so we don't display the + * Replaces line in such cases. + */ + if (nrels <= 1 && !found_non_result && + result->result_type == RESULT_TYPE_SCAN) + return; + + /* Say what we replaced, with list of rels if available. */ + if (buf.len == 0) + ExplainPropertyText("Replaces", replacement_type, es); + else + { + char *s = psprintf("%s on %s", replacement_type, buf.data); + + ExplainPropertyText("Replaces", s, es); + } +} + +/* * Explain the constituent plans of an Append, MergeAppend, * BitmapAnd, or BitmapOr node. * |