memgraph/tests/benchmark
florijan 1e0ac8ab8f Write-ahead log
Summary:
My dear fellow Memgraphians. It's friday afternoon, and I am as ready to pop as WAL is to get reviewed...

What's done:
- Vertices and Edges have global IDs, stored in `VersionList`. Main storage is now a concurrent map ID->vlist_ptr.
- WriteAheadLog class added. It's based around buffering WAL::Op objects (elementraly DB changes) and periodically serializing and flusing them to disk.
- Snapshot recovery refactored, WAL recovery added. Snapshot format changed again to include necessary info.
- Durability testing completely reworked.

What's not done (and should be when we decide how):
- Old WAL file purging.
- Config refactor (naming and organization). Will do when we discuss what we want.
- Changelog and new feature documentation (both depending on the point above).
- Better error handling and recovery feedback. Currently it's all returning bools, which is not fine-grained enough (neither for errors nor partial successes, also EOF is reported as a failure at the moment).
- Moving the implementation of WAL stuff to .cpp where possible.
- Not sure if there are transactions being created outside of `GraphDbAccessor` and it's `BuildIndex`. Need to look into.
- True write-ahead logic (flag controlled): not committing a DB transaction if the WAL has not flushed it's data. We can discuss the gain/effort ratio for this feature.

Reviewers: buda, mislav.bradac, teon.banek, dgleich

Reviewed By: dgleich

Subscribers: mtomic, pullbot

Differential Revision: https://phabricator.memgraph.io/D958
2017-11-13 09:51:39 +01:00
..
data_structures RingBuffer - buffer on heap instead of stack 2017-11-02 12:07:23 +01:00
query Remove Dbms 2017-10-30 12:33:29 +01:00
CMakeLists.txt Remove unused stuff from CMakeLists 2017-10-16 13:45:18 +02:00
edge_storage.cpp Edge storage benchmark added 2017-09-08 13:12:20 +02:00
expansion.cpp Remove Dbms 2017-10-30 12:33:29 +01:00
mvcc.cpp Write-ahead log 2017-11-13 09:51:39 +01:00