From baa146f17613e1df7089396ee4c1ee93f33b5335 Mon Sep 17 00:00:00 2001
From: Michalis Toutoudakis <toutou@ics.forth.gr>
Date: Wed, 28 Aug 2024 13:59:55 +0300
Subject: [PATCH] Add write once option to toc store to avoid creating very
 large datasets

---
 src/fdb5/toc/TocStore.cc | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/fdb5/toc/TocStore.cc b/src/fdb5/toc/TocStore.cc
index e61a981cc..a198bd99c 100644
--- a/src/fdb5/toc/TocStore.cc
+++ b/src/fdb5/toc/TocStore.cc
@@ -105,7 +105,10 @@ bool TocStore::exists() const {
 eckit::DataHandle* TocStore::retrieve(Field& field) const {
     return field.dataHandle();
 }
-
+#define write_once
+bool written_once = false;
+long len = 0;
+eckit::Offset position = 0;
 std::unique_ptr<FieldLocation> TocStore::archive(const Key &key, const void *data, eckit::Length length) {
     dirty_ = true;
 
@@ -113,9 +116,19 @@ std::unique_ptr<FieldLocation> TocStore::archive(const Key &key, const void *dat
 
     eckit::DataHandle &dh = getDataHandle(dataPath);
 
-    eckit::Offset position = dh.position();
+    
 
-    long len = dh.write( data, length );
+#ifdef write_once
+    // michalis hack
+    if (written_once == false){
+        position = dh.position();
+        len = dh.write( data, length );
+        written_once = true;
+    }
+#else   
+
+    eckit::Offset position = dh.position();
+#endif
 
     ASSERT(len == length);