1 files changed, 81 insertions, 0 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 5c823250bc2..81c91039e40 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -35,6 +35,7 @@
 #include "catalog/pg_operator.h"
 #include "catalog/pg_partitioned_table.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_statistic_ext.h"
 #include "catalog/pg_trigger.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
@@ -317,6 +318,7 @@ static char *pg_get_indexdef_worker(Oid indexrelid, int colno,
 					   const Oid *excludeOps,
 					   bool attrsOnly, bool showTblSpc,
 					   int prettyFlags, bool missing_ok);
+static char *pg_get_statisticsext_worker(Oid statextid, bool missing_ok);
 static char *pg_get_partkeydef_worker(Oid relid, int prettyFlags,
 						 bool attrsOnly);
 static char *pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
@@ -1422,6 +1424,85 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
 }
 
 /*
+ * pg_get_statisticsextdef
+ *		Get the definition of an extended statistics object
+ */
+Datum
+pg_get_statisticsextdef(PG_FUNCTION_ARGS)
+{
+	Oid			statextid = PG_GETARG_OID(0);
+	char	   *res;
+
+	res = pg_get_statisticsext_worker(statextid, true);
+
+	if (res == NULL)
+		PG_RETURN_NULL();
+
+	PG_RETURN_TEXT_P(string_to_text(res));
+}
+
+/*
+ * Internal workhorse to decompile an extended statistics object.
+ */
+static char *
+pg_get_statisticsext_worker(Oid statextid, bool missing_ok)
+{
+	Form_pg_statistic_ext	statextrec;
+	Form_pg_class			pgclassrec;
+	HeapTuple	statexttup;
+	HeapTuple	pgclasstup;
+	StringInfoData buf;
+	int			colno;
+
+	statexttup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(statextid));
+
+	if (!HeapTupleIsValid(statexttup))
+	{
+		if (missing_ok)
+			return NULL;
+		elog(ERROR, "cache lookup failed for extended statistics %u", statextid);
+	}
+
+	statextrec = (Form_pg_statistic_ext) GETSTRUCT(statexttup);
+
+	pgclasstup = SearchSysCache1(RELOID, ObjectIdGetDatum(statextrec->starelid));
+
+	if (!HeapTupleIsValid(statexttup))
+	{
+		ReleaseSysCache(statexttup);
+		elog(ERROR, "cache lookup failed for relation %u", statextrec->starelid);
+	}
+
+	pgclassrec = (Form_pg_class) GETSTRUCT(pgclasstup);
+
+	initStringInfo(&buf);
+
+	appendStringInfo(&buf, "CREATE STATISTICS %s ON (",
+							quote_identifier(NameStr(statextrec->staname)));
+
+	for (colno = 0; colno < statextrec->stakeys.dim1; colno++)
+	{
+		AttrNumber	attnum = statextrec->stakeys.values[colno];
+		char	   *attname;
+
+		if (colno > 0)
+			appendStringInfoString(&buf, ", ");
+
+		attname = get_relid_attribute_name(statextrec->starelid, attnum);
+
+		appendStringInfoString(&buf, quote_identifier(attname));
+	}
+
+	appendStringInfo(&buf, ") FROM %s",
+							quote_identifier(NameStr(pgclassrec->relname)));
+
+	ReleaseSysCache(statexttup);
+	ReleaseSysCache(pgclasstup);
+
+	return buf.data;
+}
+
+/*
  * pg_get_partkeydef
  *
  * Returns the partition key specification, ie, the following: