Enhancement: simple code optimization

1. Explicit inline functions.
2. Instead of checking the physical size of the file every time a tuple
is inserted, it is checked every 16 tuples.

performance result
```
create table t1(a int, b int, c int, d int, e text, f text,g text, h text) using pax with(compresstype
=zstd,compresslevel=5);

gpadmin=# insert into t1 select i, i+1,i+2,i+3, i::text, i::text, i::text, i::text from generate_series(1,5000000) i;
INSERT 0 5000000
Time: 6124.535 ms (00:06.125)
gpadmin=# insert into t1 select i, i+1,i+2,i+3, i::text, i::text, i::text, i::text from generate_series(1,5000000) i;
INSERT 0 5000000
Time: 5993.682 ms (00:05.994)

-- optimized with this commit
create table t1(a int, b int, c int, d int, e text, f text,g text, h text) using pax with(compresstype
=zstd,compresslevel=5);
gpadmin=# insert into t1 select i, i+1,i+2,i+3, i::text, i::text, i::text, i::text from generate_series(1,5000000) i;
INSERT 0 5000000
Time: 5713.184 ms (00:05.713)
gpadmin=# insert into t1 select i, i+1,i+2,i+3, i::text, i::text, i::text, i::text from generate_series(1,5000000) i;
INSERT 0 5000000
Time: 5430.221 ms (00:05.430)

```

Author: gongxun0928

contrib/pax_storage/src/cpp/access/pax_dml_state.cc

@@ -104,7 +104,7 @@ void CPaxDmlStateLocal::Reset() { cbdb::pax_memory_context = nullptr; }
 CPaxDmlStateLocal::CPaxDmlStateLocal()
     : last_oid_(InvalidOid), cb_{.func = DmlStateResetCallback, .arg = NULL} {}
 
-std::shared_ptr<CPaxDmlStateLocal::DmlStateValue>
+inline std::shared_ptr<CPaxDmlStateLocal::DmlStateValue>
 CPaxDmlStateLocal::RemoveDmlState(const Oid &oid) {
   std::shared_ptr<CPaxDmlStateLocal::DmlStateValue> value;
 
@@ -121,7 +121,7 @@ CPaxDmlStateLocal::RemoveDmlState(const Oid &oid) {
   return value;
 }
 
-std::shared_ptr<CPaxDmlStateLocal::DmlStateValue>
+inline std::shared_ptr<CPaxDmlStateLocal::DmlStateValue>
 CPaxDmlStateLocal::FindDmlState(const Oid &oid) {
   Assert(OidIsValid(oid));
 

contrib/pax_storage/src/cpp/comm/cbdb_wrappers.cc

@@ -124,12 +124,6 @@ void cbdb::MemoryCtxRegisterResetCallback(MemoryContext context,
   CBDB_WRAP_END;
 }
 
-Oid cbdb::RelationGetRelationId(Relation rel) {
-  CBDB_WRAP_START;
-  { return RelationGetRelid(rel); }
-  CBDB_WRAP_END;
-}
-
 #ifdef RUN_GTEST
 Datum cbdb::DatumFromCString(const char *src, size_t length) {
   CBDB_WRAP_START;

contrib/pax_storage/src/cpp/comm/cbdb_wrappers.h

@@ -114,8 +114,6 @@ void MemoryCtxDelete(MemoryContext memory_context);
 void MemoryCtxRegisterResetCallback(MemoryContext context,
                                     MemoryContextCallback *cb);
 
-Oid RelationGetRelationId(Relation rel);
-
 static inline void *DatumToPointer(Datum d) noexcept {
   return DatumGetPointer(d);
 }
@@ -164,6 +162,10 @@ static inline float8 DatumToFloat8(Datum d) noexcept {
   return DatumGetFloat8(d);
 }
 
+static inline Oid RelationGetRelationId(Relation rel) noexcept {
+  return RelationGetRelid(rel);
+}
+
 BpChar *BpcharInput(const char *s, size_t len, int32 atttypmod);
 VarChar *VarcharInput(const char *s, size_t len, int32 atttypmod);
 text *CstringToText(const char *s, size_t len);

contrib/pax_storage/src/cpp/storage/orc/orc_writer.cc

@@ -361,7 +361,11 @@ std::vector<std::pair<int, Datum>> OrcWriter::PrepareWriteTuple(
     // Numeric always need ensure that with the 4B header, otherwise it will
     // be converted twice in the vectorization path.
     if (required_stats_cols[i] || VARATT_IS_COMPRESSED(tts_value_vl) ||
-        VARATT_IS_EXTERNAL(tts_value_vl) || attrs->atttypid == NUMERICOID) {
+        VARATT_IS_EXTERNAL(tts_value_vl)
+#ifdef VEC_BUILD
+        || attrs->atttypid == NUMERICOID
+#endif
+    ) {
       // still detoast the origin toast
       detoast_vl = cbdb::PgDeToastDatum(tts_value_vl);
       Assert(detoast_vl != nullptr);

contrib/pax_storage/src/cpp/storage/pax.cc

@@ -49,6 +49,8 @@
 #include "storage/vec/pax_vec_reader.h"
 #endif
 
+#define PAX_SPLIT_CHECK_INTERVAL (16)
+
 namespace paxc {
 class IndexUpdaterInternal {
  public:
@@ -280,17 +282,23 @@ void TableWriter::Open() {
   // insert tuple into the aux table before inserting any tuples.
   cbdb::InsertMicroPartitionPlaceHolder(RelationGetRelid(relation_),
                                         current_blockno_);
+  cur_physical_size_ = 0;
 }
 
 void TableWriter::WriteTuple(TupleTableSlot *slot) {
   Assert(writer_);
   Assert(strategy_);
-  // should check split strategy before write tuple
-  // otherwise, may got a empty file in the disk
-  if (strategy_->ShouldSplit(writer_->PhysicalSize(), num_tuples_)) {
+  // Sampled split check to reduce PhysicalSize() overhead
+  // We first perform a sampled pre-write check to avoid empty files.
+  if ((num_tuples_ % PAX_SPLIT_CHECK_INTERVAL) == 0) {
+    cur_physical_size_ = writer_->PhysicalSize();
+  }
+  
+  if (strategy_->ShouldSplit(cur_physical_size_, num_tuples_)) {
     writer_->Close();
     writer_ = nullptr;
     Open();
+    cur_physical_size_ = 0;
   }
 
   writer_->WriteTuple(slot);

contrib/pax_storage/src/cpp/storage/pax.h

@@ -131,6 +131,7 @@ class TableWriter {
   std::vector<std::tuple<ColumnEncoding_Kind, int>> encoding_opts_;
 
   bool is_dfs_table_space_;
+  size_t cur_physical_size_ = 0;
 };
 
 class TableReader final {

contrib/pax_storage/src/cpp/storage/vec/pax_porc_adpater.cc

@@ -240,11 +240,15 @@ static void CopyDecimalBuffer(PaxColumn *column,
           column->GetBuffer(data_index_begin + non_null_offset);
 
       auto vl = (struct varlena *)DatumGetPointer(buffer);
-      Assert(!(VARATT_IS_EXTERNAL(vl) || VARATT_IS_COMPRESSED(vl) ||
-               VARATT_IS_SHORT(vl)));
       num_len = VARSIZE_ANY_EXHDR(vl);
-      // direct cast
-      numeric = (Numeric)(buffer);
+      // if it has been detoasted in OrcWriter::PrepareWriteTuple, it must be a
+      // 4 byte header varlena, so we can direct cast
+      if (unlikely(VARATT_IS_EXTERNAL(vl) || VARATT_IS_COMPRESSED(vl) ||
+           VARATT_IS_SHORT(vl))) {
+        numeric = cbdb::DatumToNumeric(PointerGetDatum(buffer));
+      } else {  // direct cast
+        numeric = (Numeric)(buffer);
+      }
 
       char *dest_buff = out_data_buffer->GetAvailableBuffer();
       Assert(out_data_buffer->Available() >= (size_t)type_len);