Refactor code into new JsonbValueAsText, and use it more

jsonb_object_field_text and jsonb_array_element_text both contained
identical copies of this code, so extract that into new routine
JsonbValueAsText.  This can also be used in other places, to measurable
performance benefit: the jsonb_each() and jsonb_array_elements()
functions can use it for outputting text forms instead of their less
efficient current implementation (because we no longer need to build
intermediate a jsonb representation of each value).

Author: Nikita Glukhov
Discussion: https://postgr.es/m/7c417f90-f95f-247e-ba63-d95e39c0ad14@postgrespro.ru

diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 667f9d9563e66c786057367cce244a607a8f3b81..01b44f5c754da350f335d7fb1e8c84237c33d7c4 100644 (file)
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -349,6 +349,7 @@ static Datum get_path_all(FunctionCallInfo fcinfo, bool as_text);
 static text *get_worker(text *json, char **tpath, int *ipath, int npath,
                                                bool normalize_results);
 static Datum get_jsonb_path_all(FunctionCallInfo fcinfo, bool as_text);
+static text *JsonbValueAsText(JsonbValue *v);
 
 /* semantic action functions for json_array_length */
 static void alen_object_start(void *state);
@@ -761,39 +762,9 @@ jsonb_object_field_text(PG_FUNCTION_ARGS)
                                                                           VARDATA_ANY(key),
                                                                           VARSIZE_ANY_EXHDR(key));
 
-       if (v != NULL)
-       {
-               text       *result = NULL;
 
-               switch (v->type)
-               {
-                       case jbvNull:
-                               break;
-                       case jbvBool:
-                               result = cstring_to_text(v->val.boolean ? "true" : "false");
-                               break;
-                       case jbvString:
-                               result = cstring_to_text_with_len(v->val.string.val, v->val.string.len);
-                               break;
-                       case jbvNumeric:
-                               result = cstring_to_text(DatumGetCString(DirectFunctionCall1(numeric_out,
-                                                                                                                                                        PointerGetDatum(v->val.numeric))));
-                               break;
-                       case jbvBinary:
-                               {
-                                       StringInfo      jtext = makeStringInfo();
-
-                                       (void) JsonbToCString(jtext, v->val.binary.data, -1);
-                                       result = cstring_to_text_with_len(jtext->data, jtext->len);
-                               }
-                               break;
-                       default:
-                               elog(ERROR, "unrecognized jsonb type: %d", (int) v->type);
-               }
-
-               if (result)
-                       PG_RETURN_TEXT_P(result);
-       }
+       if (v != NULL && v->type != jbvNull)
+               PG_RETURN_TEXT_P(JsonbValueAsText(v));
 
        PG_RETURN_NULL();
 }
@@ -878,39 +849,9 @@ jsonb_array_element_text(PG_FUNCTION_ARGS)
        }
 
        v = getIthJsonbValueFromContainer(&jb->root, element);
-       if (v != NULL)
-       {
-               text       *result = NULL;
-
-               switch (v->type)
-               {
-                       case jbvNull:
-                               break;
-                       case jbvBool:
-                               result = cstring_to_text(v->val.boolean ? "true" : "false");
-                               break;
-                       case jbvString:
-                               result = cstring_to_text_with_len(v->val.string.val, v->val.string.len);
-                               break;
-                       case jbvNumeric:
-                               result = cstring_to_text(DatumGetCString(DirectFunctionCall1(numeric_out,
-                                                                                                                                                        PointerGetDatum(v->val.numeric))));
-                               break;
-                       case jbvBinary:
-                               {
-                                       StringInfo      jtext = makeStringInfo();
 
-                                       (void) JsonbToCString(jtext, v->val.binary.data, -1);
-                                       result = cstring_to_text_with_len(jtext->data, jtext->len);
-                               }
-                               break;
-                       default:
-                               elog(ERROR, "unrecognized jsonb type: %d", (int) v->type);
-               }
-
-               if (result)
-                       PG_RETURN_TEXT_P(result);
-       }
+       if (v != NULL && v->type != jbvNull)
+               PG_RETURN_TEXT_P(JsonbValueAsText(v));
 
        PG_RETURN_NULL();
 }
@@ -1548,6 +1489,53 @@ get_jsonb_path_all(FunctionCallInfo fcinfo, bool as_text)
        }
 }
 
+/*
+ * Return the text representation of the given JsonbValue.
+ */
+static text *
+JsonbValueAsText(JsonbValue *v)
+{
+       switch (v->type)
+       {
+               case jbvNull:
+                       return NULL;
+
+               case jbvBool:
+                       return v->val.boolean ?
+                               cstring_to_text_with_len("true", 4) :
+                               cstring_to_text_with_len("false", 5);
+
+               case jbvString:
+                       return cstring_to_text_with_len(v->val.string.val,
+                                                                                       v->val.string.len);
+
+               case jbvNumeric:
+                       {
+                               Datum           cstr;
+
+                               cstr = DirectFunctionCall1(numeric_out,
+                                                                                  PointerGetDatum(v->val.numeric));
+
+                               return cstring_to_text(DatumGetCString(cstr));
+                       }
+
+               case jbvBinary:
+                       {
+                               StringInfoData jtext;
+
+                               initStringInfo(&jtext);
+                               (void) JsonbToCString(&jtext, v->val.binary.data,
+                                                                         v->val.binary.len);
+
+                               return cstring_to_text_with_len(jtext.data, jtext.len);
+                       }
+
+               default:
+                       elog(ERROR, "unrecognized jsonb type: %d", (int) v->type);
+                       return NULL;
+       }
+}
+
 /*
  * SQL function json_array_length(json) -> int
  */
@@ -1758,26 +1746,7 @@ each_worker_jsonb(FunctionCallInfo fcinfo, const char *funcname, bool as_text)
                                        values[1] = (Datum) NULL;
                                }
                                else
-                               {
-                                       text       *sv;
-
-                                       if (v.type == jbvString)
-                                       {
-                                               /* In text mode, scalar strings should be dequoted */
-                                               sv = cstring_to_text_with_len(v.val.string.val, v.val.string.len);
-                                       }
-                                       else
-                                       {
-                                               /* Turn anything else into a json string */
-                                               StringInfo      jtext = makeStringInfo();
-                                               Jsonb      *jb = JsonbValueToJsonb(&v);
-
-                                               (void) JsonbToCString(jtext, &jb->root, 0);
-                                               sv = cstring_to_text_with_len(jtext->data, jtext->len);
-                                       }
-
-                                       values[1] = PointerGetDatum(sv);
-                               }
+                                       values[1] = PointerGetDatum(JsonbValueAsText(&v));
                        }
                        else
                        {
@@ -2053,13 +2022,7 @@ elements_worker_jsonb(FunctionCallInfo fcinfo, const char *funcname,
                        /* use the tmp context so we can clean up after each tuple is done */
                        old_cxt = MemoryContextSwitchTo(tmp_cxt);
 
-                       if (!as_text)
-                       {
-                               Jsonb      *val = JsonbValueToJsonb(&v);
-
-                               values[0] = PointerGetDatum(val);
-                       }
-                       else
+                       if (as_text)
                        {
                                if (v.type == jbvNull)
                                {
@@ -2068,26 +2031,14 @@ elements_worker_jsonb(FunctionCallInfo fcinfo, const char *funcname,
                                        values[0] = (Datum) NULL;
                                }
                                else
-                               {
-                                       text       *sv;
-
-                                       if (v.type == jbvString)
-                                       {
-                                               /* in text mode scalar strings should be dequoted */
-                                               sv = cstring_to_text_with_len(v.val.string.val, v.val.string.len);
-                                       }
-                                       else
-                                       {
-                                               /* turn anything else into a json string */
-                                               StringInfo      jtext = makeStringInfo();
-                                               Jsonb      *jb = JsonbValueToJsonb(&v);
-
-                                               (void) JsonbToCString(jtext, &jb->root, 0);
-                                               sv = cstring_to_text_with_len(jtext->data, jtext->len);
-                                       }
+                                       values[0] = PointerGetDatum(JsonbValueAsText(&v));
+                       }
+                       else
+                       {
+                               /* Not in text mode, just return the Jsonb */
+                               Jsonb      *val = JsonbValueToJsonb(&v);
 
-                                       values[0] = PointerGetDatum(sv);
-                               }
+                               values[0] = PointerGetDatum(val);
                        }
 
                        tuple = heap_form_tuple(ret_tdesc, values, nulls);
@@ -4430,7 +4381,6 @@ jsonb_delete_idx(PG_FUNCTION_ARGS)
 
 /*
  * SQL function jsonb_set(jsonb, text[], jsonb, boolean)
- *
  */
 Datum
 jsonb_set(PG_FUNCTION_ARGS)
@@ -4522,7 +4472,6 @@ jsonb_delete_path(PG_FUNCTION_ARGS)
 
 /*
  * SQL function jsonb_insert(jsonb, text[], jsonb, boolean)
- *
  */
 Datum
 jsonb_insert(PG_FUNCTION_ARGS)