Add scale(numeric)

Author: Marko Tiikkaja

Author: alvherre

doc/src/sgml/func.sgml

@@ -849,6 +849,19 @@
        <entry><literal>42.44</literal></entry>
       </row>
 
+      <row>
+       <entry>
+        <indexterm>
+         <primary>scale</primary>
+        </indexterm>
+        <literal><function>scale(<type>numeric</type>)</function></literal>
+       </entry>
+       <entry><type>numeric</type></entry>
+       <entry>scale of the argument (the number of decimal digits in the fractional part)</entry>
+       <entry><literal>scale(8.41)</literal></entry>
+       <entry><literal>2</literal></entry>
+      </row>
+
       <row>
        <entry>
         <indexterm>

src/backend/utils/adt/numeric.c

@@ -2825,6 +2825,23 @@ numeric_power(PG_FUNCTION_ARGS)
 	PG_RETURN_NUMERIC(res);
 }
 
+/*
+ * numeric_scale() -
+ *
+ *	Returns the scale, i.e. the count of decimal digits in the fractional part
+ */
+Datum
+numeric_scale(PG_FUNCTION_ARGS)
+{
+	Numeric		num = PG_GETARG_NUMERIC(0);
+
+	if (NUMERIC_IS_NAN(num))
+		PG_RETURN_NULL();
+
+	PG_RETURN_INT32(NUMERIC_DSCALE(num));
+}
+
+
 
 /* ----------------------------------------------------------------------
  *

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201601051
+#define CATALOG_VERSION_NO	201601052
 
 #endif

src/include/catalog/pg_proc.h

@@ -2361,6 +2361,8 @@ DESCR("exponentiation");
 DATA(insert OID = 2169 ( power					PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 1700 "1700 1700" _null_ _null_ _null_ _null_ _null_	numeric_power _null_ _null_ _null_ ));
 DESCR("exponentiation");
 DATA(insert OID = 1739 ( numeric_power			PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 1700 "1700 1700" _null_ _null_ _null_ _null_ _null_	numeric_power _null_ _null_ _null_ ));
+DATA(insert OID = 8888 ( scale					PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 23 "1700" _null_ _null_ _null_ _null_ _null_ numeric_scale _null_ _null_ _null_ ));
+DESCR("number of decimal digits in the fractional part");
 DATA(insert OID = 1740 ( numeric				PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 1700 "23" _null_ _null_ _null_ _null_ _null_ int4_numeric _null_ _null_ _null_ ));
 DESCR("convert int4 to numeric");
 DATA(insert OID = 1741 ( log					PGNSP PGUID 14 1 0 0 0 f f f f t f i s 1 0 1700 "1700" _null_ _null_ _null_ _null_ _null_ "select pg_catalog.log(10, $1)" _null_ _null_ _null_ ));

src/include/utils/builtins.h

@@ -1022,6 +1022,7 @@ extern Datum numeric_exp(PG_FUNCTION_ARGS);
 extern Datum numeric_ln(PG_FUNCTION_ARGS);
 extern Datum numeric_log(PG_FUNCTION_ARGS);
 extern Datum numeric_power(PG_FUNCTION_ARGS);
+extern Datum numeric_scale(PG_FUNCTION_ARGS);
 extern Datum int4_numeric(PG_FUNCTION_ARGS);
 extern Datum numeric_int4(PG_FUNCTION_ARGS);
 extern Datum int8_numeric(PG_FUNCTION_ARGS);

src/test/regress/expected/numeric.out

@@ -1852,3 +1852,60 @@ select log(3.1954752e47, 9.4792021e-73);
  -1.51613372350688302142917386143459361608600157692779164475351842333265418126982165
 (1 row)
 
+--
+-- Tests for scale()
+--
+select scale(numeric 'NaN');
+ scale 
+-------
+      
+(1 row)
+
+select scale(NULL::numeric);
+ scale 
+-------
+      
+(1 row)
+
+select scale(1.12);
+ scale 
+-------
+     2
+(1 row)
+
+select scale(0);
+ scale 
+-------
+     0
+(1 row)
+
+select scale(0.00);
+ scale 
+-------
+     2
+(1 row)
+
+select scale(1.12345);
+ scale 
+-------
+     5
+(1 row)
+
+select scale(110123.12475871856128);
+ scale 
+-------
+    14
+(1 row)
+
+select scale(-1123.12471856128);
+ scale 
+-------
+    11
+(1 row)
+
+select scale(-13.000000000000000);
+ scale 
+-------
+    15
+(1 row)
+

src/test/regress/sql/numeric.sql

@@ -983,3 +983,17 @@ select log(1.23e-89, 6.4689e45);
 select log(0.99923, 4.58934e34);
 select log(1.000016, 8.452010e18);
 select log(3.1954752e47, 9.4792021e-73);
+
+--
+-- Tests for scale()
+--
+
+select scale(numeric 'NaN');
+select scale(NULL::numeric);
+select scale(1.12);
+select scale(0);
+select scale(0.00);
+select scale(1.12345);
+select scale(110123.12475871856128);
+select scale(-1123.12471856128);
+select scale(-13.000000000000000);