remove unnecessary comment and update Cargo.lock

Cargo.lock

@@ -183,6 +183,17 @@ version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7d5ca2cd0adc3f48f9e9ea5a6bbdf9ccc0bfade884847e484d452414c7ccffb3"
 
+[[package]]
+name = "bigdecimal"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "460825c9e21708024d67c07057cd5560e5acdccac85de0de624a81d3de51bacb"
+dependencies = [
+ "num-bigint",
+ "num-integer",
+ "num-traits",
+]
+
 [[package]]
 name = "bitflags"
 version = "1.2.1"
@@ -1682,6 +1693,7 @@ dependencies = [
  "async-std",
  "async-stream",
  "base64 0.12.0",
+ "bigdecimal",
  "bitflags",
  "byteorder",
  "chrono",

sqlx-core/src/postgres/types/bigdecimal.rs

@@ -115,7 +115,6 @@ impl TryFrom<PgNumeric> for BigDecimal {
             PgNumericSign::Negative => Sign::Minus,
         };
 
-        // `scale` is effectively the number of places left to shift the decimal point
         // weight is 0 if the decimal point falls after the first base-10000 digit
         let scale = (digits.len() as i64 - weight as i64 - 1) * 4;