From: Pavan Deolasee <pavan.deolasee@gmail.com>
Date: Tue, 15 Mar 2016 03:09:58 +0000 (+0530)
Subject: Add support for json_agg() pushdown
X-Git-Tag: XL9_5_R1BETA2~20
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=c72926ee9f964478597f5de17731130541814020;p=postgres-xl.git

Add support for json_agg() pushdown

This patch adds a collection function for json_agg() aggregate. Also use a
specific json_agg_state type for the internal agg state so that corresponding
in/out functions can be specified for transition values to be passed around
from one node to another
---

diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index af97fc1eff..bf2bb72545 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -276,6 +276,45 @@ json_recv(PG_FUNCTION_ARGS)
 	PG_RETURN_TEXT_P(cstring_to_text_with_len(str, nbytes));
 }
 
+#ifdef XCP
+Datum
+json_agg_state_in(PG_FUNCTION_ARGS)
+{
+	char	   *str = pstrdup(PG_GETARG_CSTRING(0));
+	JsonAggState *state;
+	char *token, *freestr;
+
+	state = (JsonAggState *) palloc0(sizeof (JsonAggState));
+	state->str = makeStringInfo();
+
+	freestr = str;
+
+	token = strsep(&str, ":");
+	state->val_category = atoi(token);
+	appendStringInfoString(state->str, str);
+
+	pfree(freestr);
+
+	PG_RETURN_POINTER(state);
+}
+
+/*
+ * json_agg_collectfn only needs the 'val_category' for formatting purposes. So
+ * only output that along with the json string
+ */
+Datum
+json_agg_state_out(PG_FUNCTION_ARGS)
+{
+	JsonAggState *state = (JsonAggState *) PG_GETARG_POINTER(0);
+	char *result;
+	int len = 15 + strlen(state->str->data);
+
+	result = (char *) palloc0(len);
+	sprintf(result, "%d:%s", state->val_category, state->str->data);
+
+	PG_RETURN_CSTRING(result);
+}
+#endif
 /*
  * makeJsonLexContext
  *
@@ -1888,7 +1927,13 @@ json_agg_transfn(PG_FUNCTION_ARGS)
 		state->str = makeStringInfo();
 		MemoryContextSwitchTo(oldcontext);
 
+#ifndef XCP
+		/* 
+		 * Do not add the start marker. It will be done by the
+		 * json_agg_collectfn on receiving the first result
+		 */
 		appendStringInfoChar(state->str, '[');
+#endif
 		json_categorize_type(arg_type, &state->val_category,
 							 &state->val_output_func);
 	}
@@ -1927,6 +1972,70 @@ json_agg_transfn(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(state);
 }
 
+#ifdef XCP
+/*
+ * json_agg collection function
+ */
+Datum
+json_agg_collectfn(PG_FUNCTION_ARGS)
+{
+	MemoryContext aggcontext,
+				oldcontext;
+	JsonAggState *collectstate;
+	JsonAggState *transstate;
+
+	if (!AggCheckCallContext(fcinfo, &aggcontext))
+	{
+		/* cannot be called directly because of internal-type argument */
+		elog(ERROR, "json_agg_collectfn called in non-aggregate context");
+	}
+
+
+	/* cannot be called directly because of internal-type argument */
+	Assert(AggCheckCallContext(fcinfo, NULL));
+
+	if (PG_ARGISNULL(0))
+	{
+		/*
+		 * Make this state object in a context where it will persist for the
+		 * duration of the aggregate call.  MemoryContextSwitchTo is only
+		 * needed the first time, as the StringInfo routines make sure they
+		 * use the right context to enlarge the object if necessary.
+		 */
+		oldcontext = MemoryContextSwitchTo(aggcontext);
+		collectstate = (JsonAggState *) palloc(sizeof(JsonAggState));
+		collectstate->str = makeStringInfo();
+		MemoryContextSwitchTo(oldcontext);
+
+		appendStringInfoChar(collectstate->str, '[');
+	}
+	else
+	{
+		collectstate = (JsonAggState *) PG_GETARG_POINTER(0);
+		if (!PG_ARGISNULL(1))
+			appendStringInfoString(collectstate->str, ", ");
+	}
+
+	/* fast path for NULLs */
+	if (PG_ARGISNULL(1))
+		PG_RETURN_POINTER(collectstate);
+
+	transstate = (JsonAggState *) PG_GETARG_POINTER(1);
+
+	/* add some whitespace if structured type and not first item */
+	if (!PG_ARGISNULL(0) &&
+		(transstate->val_category == JSONTYPE_ARRAY ||
+		 transstate->val_category == JSONTYPE_COMPOSITE))
+	{
+		appendStringInfoString(collectstate->str, "\n ");
+	}
+
+	appendStringInfoString(collectstate->str, transstate->str->data);
+
+	PG_RETURN_POINTER(collectstate);
+}
+#endif
+
 /*
  * json_agg final function
  */
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index ebbd118d88..6d8ade4156 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -306,7 +306,7 @@ DATA(insert ( 3538	n 0 string_agg_transfn	-	string_agg_finalfn	-				-				-				f
 DATA(insert ( 3545	n 0 bytea_string_agg_transfn	-	bytea_string_agg_finalfn	-				-				-		f f 0	2281	0	0	0		0	_null_	_null_ _null_ ));
 
 /* json */
-DATA(insert ( 3175	n 0 json_agg_transfn	-	json_agg_finalfn			-				-				-				f f 0	2281	0	0	0		0	_null_ _null_ _null_ ));
+DATA(insert ( 3175	n 0 json_agg_transfn	json_agg_collectfn json_agg_finalfn			-				-				- f f 0	7028	7028	0	0	0	_null_ _null_ _null_ ));
 DATA(insert ( 3197	n 0 json_object_agg_transfn -	json_object_agg_finalfn -				-				-				f f 0	2281	0	0	0		0	_null_ _null_ _null_ ));
 
 /* jsonb */
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index ede11ebc18..14214df39f 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -4403,9 +4403,11 @@ DATA(insert OID = 3155 (  row_to_json	   PGNSP PGUID 12 1 0 0 0 f f f f t f s 1
 DESCR("map row to json");
 DATA(insert OID = 3156 (  row_to_json	   PGNSP PGUID 12 1 0 0 0 f f f f t f s 2 0 114 "2249 16" _null_ _null_ _null_ _null_ _null_ row_to_json_pretty _null_ _null_ _null_ ));
 DESCR("map row to json with optional pretty printing");
-DATA(insert OID = 3173 (  json_agg_transfn	 PGNSP PGUID 12 1 0 0 0 f f f f f f s 2 0 2281 "2281 2283" _null_ _null_ _null_ _null_ _null_ json_agg_transfn _null_ _null_ _null_ ));
+DATA(insert OID = 3173 (  json_agg_transfn	 PGNSP PGUID 12 1 0 0 0 f f f f f f s 2 0 7028 "7028 2283" _null_ _null_ _null_ _null_ _null_ json_agg_transfn _null_ _null_ _null_ ));
 DESCR("json aggregate transition function");
-DATA(insert OID = 3174 (  json_agg_finalfn	 PGNSP PGUID 12 1 0 0 0 f f f f f f i 1 0 114 "2281" _null_ _null_ _null_ _null_ _null_ json_agg_finalfn _null_ _null_ _null_ ));
+DATA(insert OID = 7029 (  json_agg_collectfn	 PGNSP PGUID 12 1 0 0 0 f f f f f f s 2 0 7028 "7028 7028" _null_ _null_ _null_ _null_ _null_ json_agg_collectfn _null_ _null_ _null_ ));
+DESCR("json aggregate collection function");
+DATA(insert OID = 3174 (  json_agg_finalfn	 PGNSP PGUID 12 1 0 0 0 f f f f f f i 1 0 114 "7028" _null_ _null_ _null_ _null_ _null_ json_agg_finalfn _null_ _null_ _null_ ));
 DESCR("json aggregate final function");
 DATA(insert OID = 3175 (  json_agg		   PGNSP PGUID 12 1 0 0 0 t f f f f f s 1 0 114 "2283" _null_ _null_ _null_ _null_ _null_ aggregate_dummy _null_ _null_ _null_ ));
 DESCR("aggregate input into json");
@@ -5318,6 +5320,10 @@ DATA(insert OID = 7022 (  numeric_poly_agg_state_recv		   PGNSP PGUID 12 1 0 0 0
 DESCR("I/O");
 DATA(insert OID = 7023 (  numeric_poly_agg_state_send		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 17 "7019" _null_ _null_ _null_ _null_ _null_ numeric_poly_agg_state_send _null_ _null_ _null_ ));
 DESCR("I/O");
+DATA(insert OID = 7030 ( json_agg_state_in				PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 7028 "2275" _null_ _null_ _null_ _null_ _null_ json_agg_state_in _null_ _null_ _null_ ));
+DESCR("I/O");
+DATA(insert OID = 7025 ( json_agg_state_out			PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 2275 "7028" _null_ _null_ _null_ _null_ _null_ json_agg_state_out _null_ _null_ _null_ ));
+DESCR("I/O");
 #endif
 /* pg_upgrade support */
 DATA(insert OID = 3582 ( binary_upgrade_set_next_pg_type_oid PGNSP PGUID  12 1 0 0 0 f f f f t f v 1 0 2278 "26" _null_ _null_ _null_ _null_ _null_ binary_upgrade_set_next_pg_type_oid _null_ _null_ _null_ ));
diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index 571b503907..855c98c64d 100644
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -707,6 +707,10 @@ DATA(insert OID = 7019 ( numeric_poly_agg_state	   PGNSP PGUID SIZEOF_POINTER t
 DESCR("numeric_poly_agg_state - internal type used for numeric/int8 aggregation");
 #define NUMERIC_POLY_AGG_STATE_OID		7019
 
+DATA(insert OID = 7028 ( json_agg_state	   PGNSP PGUID SIZEOF_POINTER t p C f t \054 0 0 0 json_agg_state_in json_agg_state_out - - - - - ALIGNOF_POINTER p f 0 -1 0 0 _null_ _null_ _null_ ));
+DESCR("json_agg_state - internal type used for json aggregation");
+#define JSON_AGG_STATE_OID		7028
+
 /*
  * macros
  */
diff --git a/src/include/utils/json.h b/src/include/utils/json.h
index 6f69403f3d..11960bbf2c 100644
--- a/src/include/utils/json.h
+++ b/src/include/utils/json.h
@@ -22,6 +22,10 @@ extern Datum json_in(PG_FUNCTION_ARGS);
 extern Datum json_out(PG_FUNCTION_ARGS);
 extern Datum json_recv(PG_FUNCTION_ARGS);
 extern Datum json_send(PG_FUNCTION_ARGS);
+#ifdef XCP
+extern Datum json_agg_state_in(PG_FUNCTION_ARGS);
+extern Datum json_agg_state_out(PG_FUNCTION_ARGS);
+#endif
 extern Datum array_to_json(PG_FUNCTION_ARGS);
 extern Datum array_to_json_pretty(PG_FUNCTION_ARGS);
 extern Datum row_to_json(PG_FUNCTION_ARGS);