Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 219 insertions, 0 deletions

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
new file mode 100644
index 00000000000..a37f0f9cf4b
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+++ b/src/backend/commands/explain.c
@@ -0,0 +1,219 @@
+/*-------------------------------------------------------------------------
+ *
+ * explain.c--
+ *    Explain the query execution plan
+ *
+ * Copyright (c) 1994-5, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/commands/explain.c,v 1.1.1.1 1996/07/09 06:21:21 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+#include "parser/catalog_utils.h"
+#include "parser/parse_query.h"	    /* for MakeTimeRange() */
+#include "nodes/plannodes.h"
+#include "tcop/tcopprot.h"
+#include "utils/elog.h"
+#include "utils/palloc.h"
+#include "lib/stringinfo.h"
+#include "commands/explain.h"
+#include "optimizer/planner.h"
+#include "access/xact.h"
+
+typedef struct ExplainState {
+    /* options */
+    int		printCost;	/* print cost */
+    int		printNodes;	/* do nodeToString() instead */
+    /* other states */
+    List 	*rtable;	/* range table */
+} ExplainState;
+
+static char *Explain_PlanToString(Plan *plan, ExplainState *es);
+
+/*
+ * ExplainQuery -
+ *    print out the execution plan for a given query
+ *
+ */
+void
+ExplainQuery(Query *query, List *options, CommandDest dest)
+{
+    char *s;
+    Plan *plan;
+    ExplainState *es;
+    int len;
+
+    if (IsAbortedTransactionBlockState()) {
+	char *tag = "*ABORT STATE*";
+	EndCommand(tag, dest);
+		
+	elog(NOTICE, "(transaction aborted): %s",
+	     "queries ignored until END");
+		
+	return;
+    }
+
+    /* plan the queries (XXX we've ignored rewrite!!) */
+    plan = planner(query);
+
+    /* pg_plan could have failed */
+    if (plan == NULL)
+	return;
+
+    es = (ExplainState*)malloc(sizeof(ExplainState));
+    memset(es, 0, sizeof(ExplainState));
+
+    /* parse options */
+    while (options) {
+	char *ostr = strVal(lfirst(options));
+	if (!strcasecmp(ostr, "cost"))
+	    es->printCost = 1;
+	else if (!strcasecmp(ostr, "full_plan"))
+	    es->printNodes = 1;
+
+	options = lnext(options);
+    }
+    es->rtable = query->rtable;
+
+    if (es->printNodes) {
+	s = nodeToString(plan);
+    } else {
+	s = Explain_PlanToString(plan, es);
+    }
+
+    /* output the plan */
+    len = strlen(s);
+    elog(NOTICE, "QUERY PLAN:\n\n%.*s", ELOG_MAXLEN-64, s);
+    len -= ELOG_MAXLEN-64;
+    while (len > 0) {
+	s += ELOG_MAXLEN-64;
+	elog(NOTICE, "%.*s", ELOG_MAXLEN-64, s);
+	len -= ELOG_MAXLEN-64;
+    }
+    free(es);
+}
+
+/*****************************************************************************
+ *
+ *****************************************************************************/
+
+/*
+ * explain_outNode -
+ *    converts a Node into ascii string and append it to 'str'
+ */
+static void
+explain_outNode(StringInfo str, Plan *plan, int indent, ExplainState *es)
+{
+    char *pname;
+    char buf[1000];
+    int i;
+    
+    if (plan==NULL) {
+	appendStringInfo(str, "\n");
+	return;
+    }
+
+    switch(nodeTag(plan)) {
+    case T_Result:
+	pname = "Result";
+	break;
+    case T_Append:
+	pname = "Append";
+	break;
+    case T_NestLoop:
+	pname = "Nested Loop";
+	break;
+    case T_MergeJoin:
+	pname = "Merge Join";
+	break;
+    case T_HashJoin:
+	pname = "Hash Join";
+	break;
+    case T_SeqScan:
+	pname = "Seq Scan";
+	break;
+    case T_IndexScan:
+	pname = "Index Scan";
+	break;
+    case T_Temp:
+	pname = "Temp Scan";
+	break;
+    case T_Sort:
+	pname = "Sort";
+	break;
+    case T_Agg:
+	pname = "Aggregate";
+	break;
+    case T_Unique:
+	pname = "Unique";
+	break;
+    case T_Hash:
+	pname = "Hash";
+	break;
+    case T_Tee:
+	pname = "Tee";
+	break;
+    default:
+	break;
+    }
+
+    for(i=0; i < indent; i++)
+	appendStringInfo(str, "  ");
+
+    appendStringInfo(str, pname);
+    switch(nodeTag(plan)) {
+    case T_SeqScan:
+    case T_IndexScan:
+	if (((Scan*)plan)->scanrelid > 0) {
+	    RangeTblEntry *rte = nth(((Scan*)plan)->scanrelid-1, es->rtable);
+	    sprintf(buf, " on %.*s", NAMEDATALEN, rte->refname);
+	    appendStringInfo(str, buf);
+	}
+	break;
+    default:
+	break;
+    }
+    if (es->printCost) {
+	sprintf(buf, "  (cost=%.2f size=%d width=%d)",
+		plan->cost, plan->plan_size, plan->plan_width);
+	appendStringInfo(str, buf);
+    }
+    appendStringInfo(str, "\n");
+
+    /* lefttree */
+    if (outerPlan(plan)) {
+	for(i=0; i < indent; i++)
+	    appendStringInfo(str, "  ");
+	appendStringInfo(str, "  -> ");
+	explain_outNode(str, outerPlan(plan), indent+1, es);
+    }
+
+    /* righttree */
+    if (innerPlan(plan)) {
+	for(i=0; i < indent; i++)
+	    appendStringInfo(str, "  ");
+	appendStringInfo(str, "  -> ");
+	explain_outNode(str, innerPlan(plan), indent+1, es);
+    }
+    return;
+}
+
+static char *
+Explain_PlanToString(Plan *plan, ExplainState *es)
+{
+    StringInfo str;
+    char *s;
+    
+    if (plan==NULL)
+	return "";
+    Assert(plan!=NULL);
+    str = makeStringInfo();
+    explain_outNode(str, plan, 0, es);
+    s = str->data;
+    pfree(str);
+
+    return s;
+}