diff --git a/src/common/backend/utils/adt/formatting.cpp b/src/common/backend/utils/adt/formatting.cpp
index b8cad6dda1274837f8a5aab1076a3a13b671b9e6..394e45306149d7b9a5463f5ad29beb6e1123dffc 100644
--- a/src/common/backend/utils/adt/formatting.cpp
+++ b/src/common/backend/utils/adt/formatting.cpp
@@ -4636,6 +4636,12 @@ Datum blob_to_char_default(PG_FUNCTION_ARGS)
     PG_RETURN_DATUM(result);
 }
 
+Datum unknown_to_char2(PG_FUNCTION_ARGS)
+{
+    Datum result = DirectFunctionCall2(numeric_to_char, PG_GETARG_DATUM(0), PG_GETARG_DATUM(1));
+    PG_RETURN_DATUM(result);
+}
+
 /* ---------------------
  * TO_TIMESTAMP()
  *
@@ -7066,20 +7072,24 @@ Datum numeric_to_text_number(PG_FUNCTION_ARGS)
                     // Number description: fmt
                     NUMDesc numDesc;
                     bool shouldFree = false;
+                    fmt = PG_GETARG_TEXT_P(4);
                     int len = VARSIZE(fmt) - VARHDRSZ;
                     FormatNode* format = NUM_cache(len, &numDesc, fmt, &shouldFree);
                     // Integer digits
-                    unsigned int formatPrecision = Max(0, numDesc.pre);
+                    unsigned int formatPrePrecision = Max(0, numDesc.pre);
+                    // Decimal digits
+                    unsigned int formatPostPrecision = Max(0, numDesc.post);
                     if (shouldFree)
                         pfree_ext(format);
 
                     // Calculate the formatPrecision power of 10.
-                    double powerOfMax = pow(10, formatPrecision);
+                    double powerOfPreMax = pow(10, formatPrePrecision) - 1;
+                    double powerOfPostMax = (pow(10, formatPostPrecision) - 1) / pow(10, formatPostPrecision);
 
                     // into numeric_float8 func
                     double defaultValue = (double)DatumGetFloat8(DirectFunctionCall1(numeric_float8, 
                         NumericGetDatum(defaultNumVal)));
-                    if (defaultValue > (powerOfMax - 1)) {
+                    if (defaultValue > (powerOfPreMax + powerOfPostMax)) {
                         ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), 
                             errmsg("Exceeding the maximum value required by fmt")));
                     }
@@ -7148,6 +7158,7 @@ Datum numeric_to_default_without_defaultval(PG_FUNCTION_ARGS)
                     result = to_numeric_number_internal_without_fmt(default_num_val,
 						PG_GET_COLLATION(), &resultNull);
                 } else {
+                    fmt = PG_GETARG_TEXT_P(4);
                     result = to_numeric_to_number_internal(default_num_val, fmt,
 						PG_GET_COLLATION(), &resultNull);
                 }
diff --git a/src/test/regress/expected/to_number_default.out b/src/test/regress/expected/to_number_default.out
index 0fc7b2da0826a422d3eda06b7e0e6c226805cdd6..43be63f8b054e181733d730e763b054928810cc8 100644
--- a/src/test/regress/expected/to_number_default.out
+++ b/src/test/regress/expected/to_number_default.out
@@ -280,6 +280,18 @@ SELECT TO_NUMBER(3.14 DEFAULT c1 ON CONVERSION ERROR) FROM tonumber ORDER By c1;
       3.14
 (7 rows)
 
+SELECT to_number('<1234>' DEFAULT 999 ON CONVERSION ERROR,'PR9999999');
+ERROR:  "9" must be ahead of "PR"
+CONTEXT:  referenced column: to_number
+SELECT  TO_NUMBER('1234.56' default 999 on conversion error ,'99.99');
+ERROR:  Exceeding the maximum value required by fmt
+CONTEXT:  referenced column: to_number
+SELECT  TO_NUMBER('1234.56' default 999.1 on conversion error ,'999.99');
+ to_number 
+-----------
+     999.1
+(1 row)
+
 SELECT TO_NUMBER(c2 DEFAULT 3.14 ON CONVERSION ERROR) FROM tonumber ORDER By c1;
                 to_number                
 -----------------------------------------
diff --git a/src/test/regress/sql/to_number_default.sql b/src/test/regress/sql/to_number_default.sql
index 15516dbf67d2dbfe50dca1cf33209e2ab72c182f..76df3a529e9c96567be5888a3be6d21b1f819a7c 100644
--- a/src/test/regress/sql/to_number_default.sql
+++ b/src/test/regress/sql/to_number_default.sql
@@ -60,6 +60,9 @@ SELECT TO_NUMBER(c1 DEFAULT NULL ON CONVERSION ERROR) FROM tonumber ORDER By c1;
 
 SELECT TO_NUMBER('abd' DEFAULT c1 ON CONVERSION ERROR) FROM tonumber ORDER By c1;  -- error， Default param can't be ColumnRef
 SELECT TO_NUMBER(3.14 DEFAULT c1 ON CONVERSION ERROR) FROM tonumber ORDER By c1;  -- error， Default param can't be ColumnRef
+SELECT to_number('<1234>' DEFAULT 999 ON CONVERSION ERROR,'PR9999999');
+SELECT  TO_NUMBER('1234.56' default 999 on conversion error ,'99.99');
+SELECT  TO_NUMBER('1234.56' default 999.1 on conversion error ,'999.99');
 
 SELECT TO_NUMBER(c2 DEFAULT 3.14 ON CONVERSION ERROR) FROM tonumber ORDER By c1;
 SELECT TO_NUMBER(c2 DEFAULT '3.14' ON CONVERSION ERROR) FROM tonumber ORDER By c1;
@@ -283,4 +286,4 @@ SELECT * FROM tonumber_exec ORDER BY c1;
 DROP TABLE tonumber;
 DROP TABLE tonumber_exec;
 
-drop schema if exists func_to_number cascade;
\ No newline at end of file
+drop schema if exists func_to_number cascade;