Fixes #2164: Adds support for PostgreSQL 18

1. In PostgreSQL 18, TupleDescAttr is now used to access
ScanTuple->tts_tupleDescriptor->attrs since attrs is now replaced by
compact_attrs to save on memory in PostgreSQL 18. In PostgreSQL 16, 17
and 18 we have a function TupleDescAttr which allows to acess pg_attrs
2. In PostgreSQL palloc0fast is now merged into palloc0.
3. Few funcitons now reuiqre executor/executor.h and are no longer
present in the other includes.

Author: sanchayanghosh

src/backend/catalog/ag_label.c

@@ -29,6 +29,7 @@
 #include "catalog/ag_label.h"
 #include "commands/label_commands.h"
 #include "executor/cypher_utils.h"
+#include "executor/executor.h"
 #include "utils/ag_cache.h"
 
 /*

src/backend/executor/cypher_create.c

@@ -20,8 +20,10 @@
 #include "postgres.h"
 
 #include "catalog/ag_label.h"
+#include "catalog/indexing.h"
 #include "executor/cypher_executor.h"
 #include "executor/cypher_utils.h"
+#include "executor/executor.h"
 
 static void begin_cypher_create(CustomScanState *node, EState *estate,
                                 int eflags);

src/backend/executor/cypher_delete.c

@@ -25,6 +25,8 @@
 #include "catalog/ag_label.h"
 #include "executor/cypher_executor.h"
 #include "executor/cypher_utils.h"
+#include "executor/executor.h"
+#include "pg_config.h"
 
 static void begin_cypher_delete(CustomScanState *node, EState *estate,
                                 int eflags);
@@ -55,6 +57,11 @@ const CustomExecMethods cypher_delete_exec_methods = {DELETE_SCAN_STATE_NAME,
                                                       NULL,
                                                       NULL};
 
+#if PG_VERSION_NUM >= 18000 
+#define TUPLE_DESC_ATTR_TYPE_ID TupleDescAttr(tupleDescriptor, entity_position - 1)->atttypid
+#else
+#define TUPLE_DESC_ATTR_TYPE_ID tupleDescriptor->attrs[entity_position - 1]->atttypid
+#endif
 /*
  * Initialization at the beginning of execution. Setup the child node,
  * setup its scan tuple slot and projection info, expression context,
@@ -257,13 +264,15 @@ static agtype_value *extract_entity(CustomScanState *node,
     tupleDescriptor = scanTupleSlot->tts_tupleDescriptor;
 
     /* type checking, make sure the entity is an agtype vertex or edge */
-    if (tupleDescriptor->attrs[entity_position -1].atttypid != AGTYPEOID)
+    // First  make sure the entity is an agtype. this is set per extension. Also, from postgresql 16 onwards use TupleDescAttr so that it works on both attrs and compact_attrs.
+    if (TUPLE_DESC_ATTR_TYPE_ID != AGTYPEOID)
         ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("DELETE clause can only delete agtype")));
 
     original_entity = DATUM_GET_AGTYPE_P(scanTupleSlot->tts_values[entity_position - 1]);
     original_entity_value = get_ith_agtype_value_from_container(&original_entity->root, 0);
 
+    // We are not deleting anything other than vertices and edges.
     if (original_entity_value->type != AGTV_VERTEX && original_entity_value->type != AGTV_EDGE)
         ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("DELETE clause can only delete vertices and edges")));

src/backend/executor/cypher_merge.c

@@ -22,6 +22,7 @@
 #include "catalog/ag_label.h"
 #include "executor/cypher_executor.h"
 #include "executor/cypher_utils.h"
+#include "executor/executor.h"
 #include "utils/datum.h"
 
 /*

src/backend/executor/cypher_set.c

@@ -24,6 +24,8 @@
 #include "executor/cypher_executor.h"
 #include "executor/cypher_utils.h"
 
+#include "executor/executor.h"
+#include "pg_config.h"
 static void begin_cypher_set(CustomScanState *node, EState *estate,
                                 int eflags);
 static TupleTableSlot *exec_cypher_set(CustomScanState *node);
@@ -49,6 +51,13 @@ const CustomExecMethods cypher_set_exec_methods = {SET_SCAN_STATE_NAME,
                                                       NULL,
                                                       NULL};
 
+#if PG_VERSION_NUM >= 18000 
+#define TUPLE_DESC_ATTR_TYPE_ID TupleDescAttr(scanTupleSlot->tts_tupleDescriptor, i)->atttypid
+#define TUPLE_DESC_ATTR_TYPE_ID_ENTITY TupleDescAttr(scanTupleSlot->tts_tupleDescriptor, update_item->entity_position - 1)->atttypid
+#else
+#define TUPLE_DESC_ATTR_TYPE_ID scanTupleSlot->tts_tupleDescriptor->attrs[i]->atttypid
+#define TUPLE_DESC_ATTR_TYPE_ID_ENTITY scanTupleSlot->tts_tupleDescriptor->attrs[update_item->entity_position - 1]->atttypid
+#endif
 static void begin_cypher_set(CustomScanState *node, EState *estate,
                              int eflags)
 {
@@ -310,7 +319,8 @@ static void update_all_paths(CustomScanState *node, graphid id,
         agtype_value *original_entity_value;
 
         /* skip nulls */
-        if (scanTupleSlot->tts_tupleDescriptor->attrs[i].atttypid != AGTYPEOID)
+        // Starting postgresql version 16, tupleDescriptor->attrs access is not recommended. Instead, we must use tupleDescAttr which handles both compact_attr and attr access.
+        if (TUPLE_DESC_ATTR_TYPE_ID != AGTYPEOID)
         {
             continue;
         }
@@ -414,7 +424,8 @@ static void process_update_list(CustomScanState *node)
             continue;
         }
 
-        if (scanTupleSlot->tts_tupleDescriptor->attrs[update_item->entity_position -1].atttypid != AGTYPEOID)
+        // Starting from postgresql 16, we need to use TupleDescAttr for accessing tupleDescriptor because attr is now no longer present under tupleDescriptor and is now compact_attr
+        if (TUPLE_DESC_ATTR_TYPE_ID_ENTITY != AGTYPEOID)
         {
             ereport(ERROR,
                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

src/backend/executor/cypher_utils.c

@@ -30,6 +30,7 @@
 #include "catalog/ag_label.h"
 #include "commands/label_commands.h"
 #include "executor/cypher_utils.h"
+#include "executor/executor.h"
 #include "utils/ag_cache.h"
 
 /*

src/backend/nodes/ag_nodes.c

@@ -25,6 +25,7 @@
 #include "nodes/cypher_readfuncs.h"
 #include "nodes/cypher_nodes.h"
 
+#include "utils/palloc.h"
 static bool equal_ag_node(const ExtensibleNode *a, const ExtensibleNode *b);
 
 /* This list must match ag_node_tag. */
@@ -156,7 +157,7 @@ ExtensibleNode *_new_ag_node(Size size, ag_node_tag tag)
 {
     ExtensibleNode *n;
 
-    n = (ExtensibleNode *)palloc0fast(size);
+    n = (ExtensibleNode *)palloc0(size);
     n->type = T_ExtensibleNode;
     n->extnodename = node_names[tag];
 

src/backend/parser/cypher_clause.c

@@ -51,6 +51,8 @@
 #include "utils/ag_cache.h"
 #include "utils/ag_func.h"
 #include "utils/ag_guc.h"
+#include "nodes/primnodes.h"
+#include "pg_config.h"
 
 /*
  * Variable string names for makeTargetEntry. As they are going to be variable
@@ -2555,10 +2557,17 @@ static void get_res_cols(ParseState *pstate, ParseNamespaceItem *l_pnsi,
     List *colnames = NIL;
     List *colvars = NIL;
 
+    #if PG_VERSION_NUM >= 180000
+    expandRTE(l_pnsi->p_rte, l_pnsi->p_rtindex, 0, VAR_RETURNING_DEFAULT, -1, false,
+              &l_colnames, &l_colvars);
+    expandRTE(r_pnsi->p_rte, r_pnsi->p_rtindex, 0, VAR_RETURNING_DEFAULT, -1, false,
+              &r_colnames, &r_colvars);
+    #else
     expandRTE(l_pnsi->p_rte, l_pnsi->p_rtindex, 0, -1, false,
               &l_colnames, &l_colvars);
     expandRTE(r_pnsi->p_rte, r_pnsi->p_rtindex, 0, -1, false,
               &r_colnames, &r_colvars);
+    #endif 
 
     /* add in all colnames and colvars from the l_rte. */
     *res_colnames = list_concat(*res_colnames, l_colnames);

src/backend/utils/adt/agtype_parser.c

@@ -59,6 +59,7 @@ typedef enum /* contexts of agtype parser */
     AGTYPE_PARSE_END /* saw the end of a document, expect nothing */
 } agtype_parse_context;
 
+#define pg_attribute_noreturn() __attribute__((noreturn))
 static inline void agtype_lex(agtype_lex_context *lex);
 static inline void agtype_lex_string(agtype_lex_context *lex);
 static inline void agtype_lex_number(agtype_lex_context *lex, char *s,