Clean up jsonb code.

The main target of this cleanup is the convertJsonb() function, but I also
touched a lot of other things that I spotted into in the process.

The new convertToJsonb() function uses an output buffer that's resized on
demand, so the code to estimate of the size of JsonbValue is removed.

The on-disk format was not changed, even though I refactored the structs
used to handle it. The term "superheader" is replaced with "container".

The jsonb_exists_any and jsonb_exists_all functions no longer sort the input
array. That was a premature optimization, the idea being that if there are
duplicates in the input array, you only need to check them once. Also,
sorting the array saves some effort in the binary search used to find a key
within an object. But there were drawbacks too: the sorting and
deduplicating obviously isn't free, and in the typical case there are no
duplicates to remove, and the gain in the binary search was minimal. Remove
all that, which makes the code simpler too.

This includes a bug-fix; the total length of the elements in a jsonb array
or object mustn't exceed 2^28. That is now checked.

1 files changed, 5 insertions, 11 deletions

diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c
index cf5d6f23264..e1fe45f7128 100644
--- a/src/backend/utils/adt/jsonb.c
+++ b/src/backend/utils/adt/jsonb.c
@@ -33,7 +33,6 @@ static void jsonb_in_array_end(void *pstate);
 static void jsonb_in_object_field_start(void *pstate, char *fname, bool isnull);
 static void jsonb_put_escaped_value(StringInfo out, JsonbValue *scalarVal);
 static void jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype);
-char	   *JsonbToCString(StringInfo out, char *in, int estimated_len);
 
 /*
  * jsonb type input function
@@ -65,7 +64,7 @@ jsonb_recv(PG_FUNCTION_ARGS)
 	if (version == 1)
 		str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
 	else
-		elog(ERROR, "Unsupported jsonb version number %d", version);
+		elog(ERROR, "unsupported jsonb version number %d", version);
 
 	return jsonb_from_cstring(str, nbytes);
 }
@@ -79,7 +78,7 @@ jsonb_out(PG_FUNCTION_ARGS)
 	Jsonb	   *jb = PG_GETARG_JSONB(0);
 	char	   *out;
 
-	out = JsonbToCString(NULL, VARDATA(jb), VARSIZE(jb));
+	out = JsonbToCString(NULL, &jb->root, VARSIZE(jb));
 
 	PG_RETURN_CSTRING(out);
 }
@@ -97,7 +96,7 @@ jsonb_send(PG_FUNCTION_ARGS)
 	StringInfo	jtext = makeStringInfo();
 	int			version = 1;
 
-	(void) JsonbToCString(jtext, VARDATA(jb), VARSIZE(jb));
+	(void) JsonbToCString(jtext, &jb->root, VARSIZE(jb));
 
 	pq_begintypsend(&buf);
 	pq_sendint(&buf, version, 1);
@@ -130,7 +129,7 @@ jsonb_typeof(PG_FUNCTION_ARGS)
 	{
 		Assert(JB_ROOT_IS_SCALAR(in));
 
-		it = JsonbIteratorInit(VARDATA_ANY(in));
+		it = JsonbIteratorInit(&in->root);
 
 		/*
 		 * A root scalar is stored as an array of one element, so we get the
@@ -249,7 +248,6 @@ jsonb_in_object_field_start(void *pstate, char *fname, bool isnull)
 	v.type = jbvString;
 	v.val.string.len = checkStringLen(strlen(fname));
 	v.val.string.val = pnstrdup(fname, v.val.string.len);
-	v.estSize = sizeof(JEntry) + v.val.string.len;
 
 	_state->res = pushJsonbValue(&_state->parseState, WJB_KEY, &v);
 }
@@ -290,8 +288,6 @@ jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
 	JsonbInState *_state = (JsonbInState *) pstate;
 	JsonbValue	v;
 
-	v.estSize = sizeof(JEntry);
-
 	switch (tokentype)
 	{
 
@@ -300,7 +296,6 @@ jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
 			v.type = jbvString;
 			v.val.string.len = checkStringLen(strlen(token));
 			v.val.string.val = pnstrdup(token, v.val.string.len);
-			v.estSize += v.val.string.len;
 			break;
 		case JSON_TOKEN_NUMBER:
 
@@ -312,7 +307,6 @@ jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
 			v.type = jbvNumeric;
 			v.val.numeric = DatumGetNumeric(DirectFunctionCall3(numeric_in, CStringGetDatum(token), 0, -1));
 
-			v.estSize += VARSIZE_ANY(v.val.numeric) +sizeof(JEntry) /* alignment */ ;
 			break;
 		case JSON_TOKEN_TRUE:
 			v.type = jbvBool;
@@ -374,7 +368,7 @@ jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
  * if they are converting it to a text* object.
  */
 char *
-JsonbToCString(StringInfo out, JsonbSuperHeader in, int estimated_len)
+JsonbToCString(StringInfo out, JsonbContainer *in, int estimated_len)
 {
 	bool		first = true;
 	JsonbIterator *it;