[Commits] 3b7567781: Range Locking: More comments

Sergei Petrunia psergey at askmonty.org
Mon Apr 8 16:29:58 EEST 2019


revision-id: 3b7567781e50b1ced3583a60fa7f1a568cc42d2e (v5.8-1033-g3b7567781)
parent(s): 0ebc41a1c459263a30e2d2bc68348ed5bcdd59bd
author: Sergei Petrunia
committer: Sergei Petrunia
timestamp: 2019-04-08 16:29:58 +0300
message:

Range Locking: More comments

---
 include/rocksdb/utilities/transaction.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/rocksdb/utilities/transaction.h b/include/rocksdb/utilities/transaction.h
index 9dbba3df7..e980e032e 100644
--- a/include/rocksdb/utilities/transaction.h
+++ b/include/rocksdb/utilities/transaction.h
@@ -46,8 +46,15 @@ using TransactionID = uint64_t;
   then
     key_a < key_b.
 
-  An empty string is less than any other constant (from this it follows that
-  for any prefix and suffix, {prefix, suffix} > {prefix})
+  2. An empty string is less than any other value. From this it follows that
+  for any prefix and suffix, {prefix, suffix} > {prefix}.
+
+  3. The row comparison function can compare key prefixes. If the data domain
+  includes keys A and B, then the comparison function is able to compare
+  equal-length prefixes:
+
+    min_len= min(byte_length(A), byte_length(B));
+    cmp(Slice(A, min_len), Slice(B, min_len))
 
   == Prefix ranges ==
   With lexicographic-like ordering, one may to construct ranges from a


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