Micro-optimize datum_to_json_internal() some more.

Commit dc3f9bc549 mainly targeted the JSONTYPE_NUMERIC code path.
This commit applies similar optimizations (e.g., removing
unnecessary runtime calls to strlen() and palloc()) to nearby code.

Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20231208203708.GA4126315%40nathanxps13

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 0778d8dec927e7d16e57530d9a2fcadf7d4051d9..507c1c22b71aaa855d204dc76d918507c4231e60 100644 (file)
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -188,7 +188,7 @@ datum_to_json_internal(Datum val, bool is_null, StringInfo result,
 
    if (is_null)
    {
-       appendStringInfoString(result, "null");
+       appendBinaryStringInfo(result, "null", strlen("null"));
        return;
    }
 
@@ -210,11 +210,14 @@ datum_to_json_internal(Datum val, bool is_null, StringInfo result,
            composite_to_json(val, result, false);
            break;
        case JSONTYPE_BOOL:
-           outputstr = DatumGetBool(val) ? "true" : "false";
            if (key_scalar)
-               escape_json(result, outputstr);
+               appendStringInfoChar(result, '"');
+           if (DatumGetBool(val))
+               appendBinaryStringInfo(result, "true", strlen("true"));
            else
-               appendStringInfoString(result, outputstr);
+               appendBinaryStringInfo(result, "false", strlen("false"));
+           if (key_scalar)
+               appendStringInfoChar(result, '"');
            break;
        case JSONTYPE_NUMERIC:
            outputstr = OidOutputFunctionCall(outfuncoid, val);
@@ -277,9 +280,8 @@ datum_to_json_internal(Datum val, bool is_null, StringInfo result,
        case JSONTYPE_CAST:
            /* outfuncoid refers to a cast function, not an output function */
            jsontext = DatumGetTextPP(OidFunctionCall1(outfuncoid, val));
-           outputstr = text_to_cstring(jsontext);
-           appendStringInfoString(result, outputstr);
-           pfree(outputstr);
+           appendBinaryStringInfo(result, VARDATA_ANY(jsontext),
+                                  VARSIZE_ANY_EXHDR(jsontext));
            pfree(jsontext);
            break;
        default: