From: Adam Kupczyk <akupczyk@ibm.com>
Date: Fri, 4 Oct 2024 16:06:19 +0000 (+0000)
Subject: kv/RocksDBStore: Improve estimate_prefix_size.
X-Git-Tag: v20.0.0~193^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=22a577101e36416094a0952cbf174db5971b7374;p=ceph.git

kv/RocksDBStore: Improve estimate_prefix_size.

Modify to include both files and memtables.
Gives better prediction of data size, especially gives non-zero size
when all data is still in memtables.

Signed-off-by: Adam Kupczyk <akupczyk@ibm.com>
---

diff --git a/src/kv/RocksDBStore.cc b/src/kv/RocksDBStore.cc
index ca63ea064841..53da9cd047e1 100644
--- a/src/kv/RocksDBStore.cc
+++ b/src/kv/RocksDBStore.cc
@@ -1394,6 +1394,13 @@ bool RocksDBStore::get_property(
 int64_t RocksDBStore::estimate_prefix_size(const string& prefix,
 					   const string& key_prefix)
 {
+  // The default mode is to derive estimates based on
+  // sst files alone (INCLUDE_FILES).
+  // This gives an irritating result when a batch of keys is
+  // just commited but estimate keeps showing 0.
+  rocksdb::DB::SizeApproximationFlags flags(
+    rocksdb::DB::SizeApproximationFlags::INCLUDE_FILES |
+    rocksdb::DB::SizeApproximationFlags::INCLUDE_MEMTABLES);
   uint64_t size = 0;
   auto p_iter = cf_handles.find(prefix);
   if (p_iter != cf_handles.end()) {
@@ -1402,14 +1409,14 @@ int64_t RocksDBStore::estimate_prefix_size(const string& prefix,
       string start = key_prefix + string(1, '\x00');
       string limit = key_prefix + string("\xff\xff\xff\xff");
       rocksdb::Range r(start, limit);
-      db->GetApproximateSizes(cf, &r, 1, &s);
+      db->GetApproximateSizes(cf, &r, 1, &s, flags);
       size += s;
     }
   } else {
     string start = combine_strings(prefix , key_prefix);
     string limit = combine_strings(prefix , key_prefix + "\xff\xff\xff\xff");
     rocksdb::Range r(start, limit);
-    db->GetApproximateSizes(default_cf, &r, 1, &size);
+    db->GetApproximateSizes(default_cf, &r, 1, &size, flags);
   }
   return size;
 }