1 files changed, 120 insertions, 5 deletions

diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index aa6c19adada..b968c25dd69 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -1917,6 +1917,9 @@ generateClonedExtStatsStmt(RangeVar *heapRel, Oid heapRelid,
 			stat_types = lappend(stat_types, makeString("dependencies"));
 		else if (enabled[i] == STATS_EXT_MCV)
 			stat_types = lappend(stat_types, makeString("mcv"));
+		else if (enabled[i] == STATS_EXT_EXPRESSIONS)
+			/* expression stats are not exposed to users */
+			continue;
 		else
 			elog(ERROR, "unrecognized statistics kind %c", enabled[i]);
 	}
@@ -1924,14 +1927,47 @@ generateClonedExtStatsStmt(RangeVar *heapRel, Oid heapRelid,
 	/* Determine which columns the statistics are on */
 	for (i = 0; i < statsrec->stxkeys.dim1; i++)
 	{
-		ColumnRef  *cref = makeNode(ColumnRef);
+		StatsElem  *selem = makeNode(StatsElem);
 		AttrNumber	attnum = statsrec->stxkeys.values[i];
 
-		cref->fields = list_make1(makeString(get_attname(heapRelid,
-														 attnum, false)));
-		cref->location = -1;
+		selem->name = get_attname(heapRelid, attnum, false);
+		selem->expr = NULL;
 
-		def_names = lappend(def_names, cref);
+		def_names = lappend(def_names, selem);
+	}
+
+	/*
+	 * Now handle expressions, if there are any. The order (with respect to
+	 * regular attributes) does not really matter for extended stats, so we
+	 * simply append them after simple column references.
+	 *
+	 * XXX Some places during build/estimation treat expressions as if they
+	 * are before atttibutes, but for the CREATE command that's entirely
+	 * irrelevant.
+	 */
+	datum = SysCacheGetAttr(STATEXTOID, ht_stats,
+							Anum_pg_statistic_ext_stxexprs, &isnull);
+
+	if (!isnull)
+	{
+		ListCell   *lc;
+		List	   *exprs = NIL;
+		char	   *exprsString;
+
+		exprsString = TextDatumGetCString(datum);
+		exprs = (List *) stringToNode(exprsString);
+
+		foreach(lc, exprs)
+		{
+			StatsElem  *selem = makeNode(StatsElem);
+
+			selem->name = NULL;
+			selem->expr = (Node *) lfirst(lc);
+
+			def_names = lappend(def_names, selem);
+		}
+
+		pfree(exprsString);
 	}
 
 	/* finally, build the output node */
@@ -1942,6 +1978,7 @@ generateClonedExtStatsStmt(RangeVar *heapRel, Oid heapRelid,
 	stats->relations = list_make1(heapRel);
 	stats->stxcomment = NULL;
 	stats->if_not_exists = false;
+	stats->transformed = true;	/* don't need transformStatsStmt again */
 
 	/* Clean up */
 	ReleaseSysCache(ht_stats);
@@ -2866,6 +2903,84 @@ transformIndexStmt(Oid relid, IndexStmt *stmt, const char *queryString)
 	return stmt;
 }
 
+/*
+ * transformStatsStmt - parse analysis for CREATE STATISTICS
+ *
+ * To avoid race conditions, it's important that this function rely only on
+ * the passed-in relid (and not on stmt->relation) to determine the target
+ * relation.
+ */
+CreateStatsStmt *
+transformStatsStmt(Oid relid, CreateStatsStmt *stmt, const char *queryString)
+{
+	ParseState *pstate;
+	ParseNamespaceItem *nsitem;
+	ListCell   *l;
+	Relation	rel;
+
+	/* Nothing to do if statement already transformed. */
+	if (stmt->transformed)
+		return stmt;
+
+	/*
+	 * We must not scribble on the passed-in CreateStatsStmt, so copy it.
+	 * (This is overkill, but easy.)
+	 */
+	stmt = copyObject(stmt);
+
+	/* Set up pstate */
+	pstate = make_parsestate(NULL);
+	pstate->p_sourcetext = queryString;
+
+	/*
+	 * Put the parent table into the rtable so that the expressions can refer
+	 * to its fields without qualification.  Caller is responsible for locking
+	 * relation, but we still need to open it.
+	 */
+	rel = relation_open(relid, NoLock);
+	nsitem = addRangeTableEntryForRelation(pstate, rel,
+										   AccessShareLock,
+										   NULL, false, true);
+
+	/* no to join list, yes to namespaces */
+	addNSItemToQuery(pstate, nsitem, false, true, true);
+
+	/* take care of any expressions */
+	foreach(l, stmt->exprs)
+	{
+		StatsElem  *selem = (StatsElem *) lfirst(l);
+
+		if (selem->expr)
+		{
+			/* Now do parse transformation of the expression */
+			selem->expr = transformExpr(pstate, selem->expr,
+										EXPR_KIND_STATS_EXPRESSION);
+
+			/* We have to fix its collations too */
+			assign_expr_collations(pstate, selem->expr);
+		}
+	}
+
+	/*
+	 * Check that only the base rel is mentioned.  (This should be dead code
+	 * now that add_missing_from is history.)
+	 */
+	if (list_length(pstate->p_rtable) != 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
+				 errmsg("statistics expressions can refer only to the table being indexed")));
+
+	free_parsestate(pstate);
+
+	/* Close relation */
+	table_close(rel, NoLock);
+
+	/* Mark statement as successfully transformed */
+	stmt->transformed = true;
+
+	return stmt;
+}
+
 
 /*
  * transformRuleStmt -