Summary:
In order for this race condition to cause damage, an index/constraint must be
created/dropped at the exact moment that the GC is cleaning
indices/constraints.
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2733
Summary:
The storage now uses a file in the data directory (`.lock`) to determine
whether there is another instance of the storage running with the same data
directory. That helps notify the user/administrator that the system is running
in an unsupported configuration.
Reviewers: teon.banek, ipaljak
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2719
Summary:
This diff contains simple tests for unique constraints which tries to
change property values or labels in multiple threads at the same time.
During testing, a bug has been encountered in unique constraints, i.e.
one guard lock on vertices was missing.
Reviewers: mferencevic
Reviewed By: mferencevic
Subscribers: mferencevic, pullbot
Differential Revision: https://phabricator.memgraph.io/D2711
Summary:
This diff contains a necessary functionality to save and restore unique
constraint operations. The previous snapshot/WAL version is backward
compatible. Integration tests for migration from older snapshot and WAL
versions are also included.
Reviewers: mferencevic
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2680
Summary:
Before this change, unique constraints supported only pairs of label
and a single property. With this change, unique constraints can be
created for label and set of properties.
Better tests for unique constraints in general are also included in
this diff.
Reviewers: mferencevic, teon.banek
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2653
Summary:
This diff contains a basic implementation of unique constraints consistent with
the MVCC storage.
Stale records in the unique constraints are collected by the garbage collector.
Tests for checking correctness of unique constraints and violations are included.
Note: currently we only support a pair of label and a single property. Support for
multiple properties will be added later.
Reviewers: mferencevic, teon.banek
Reviewed By: mferencevic, teon.banek
Subscribers: buda, ipaljak, pullbot
Differential Revision: https://phabricator.memgraph.io/D2608
Summary:
The property store stores a map of `PropertyId` to `PropertyValue` mappings. It
compresses all of the values in order to use as little memory as possible.
Reviewers: teon.banek, ipaljak
Reviewed By: teon.banek
Subscribers: buda, pullbot
Differential Revision: https://phabricator.memgraph.io/D2604
Summary:
The garbage collector had a race condition when it would delete deltas that
were in the middle of an object's delta chain. In the process of deleting
(unlinking) the delta, the garbage collector previously wouldn't acquire any
locks. That operation was then racing with the standard MVCC
`CreateAndLinkDelta` function that adds a new delta into the chain.
Fortunately, `CreateAndLinkDelta` always does its modifications while holding a
lock to the owner of the chain (either a vertex or an edge) so this change just
adds the lock acquiring to the garbage collector.
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2582
Summary:
The functions that previously had locks in them are always called while the
vertex lock is already being held. Also, the lock guards were implemented
incorrectly.
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2580
Summary:
Edge filters (edge type and destination vertex) are now handled natively in the
storage API. The API is implemented to be the fastest possible when using the
filters with the assumption that the number of edge types will be small.
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2576
Summary:
Now when iterating over a label+property index the index verifies that the
bounds meet the criteria imposed by openCypher.
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2552
Summary:
Previously, when accessing the labels/properties/edges of a vertex/edge that
was just created the NEW view would correctly display the change, but the OLD
view would be invalid and would crash the database. With this change the OLD
view of a freshly created vertex/edge won't cause a crash, but will instead
report an error.
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2549
Summary:
The atomic memory order should be `acquire` for `load` operations, `release`
for `store` operations and `acq_rel` for any RMW (read-modify-write) operations
(like `fetch_add`).
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2540
Summary:
Most instances of `@throw std::bad_alloc` are left unexplained as these
functions perform general heap allocations are it's obvious from the
function name that it will do so. Basically anything with `Create`, `Make` or
`Build` implies allocations. Additionally, which parts exactly perform
allocations are an implementation detail. Functions which do unexpected
heap allocations have the reason stated in the documentation, these
functions typically have exactly one spot which could raise such an
exception.
Some functions are marked as `noexcept`, these are usually "special
functions" such as constructors and operators. This could potentially
improve performance because STL may use API overloads that work faster
with `noexcept` stuff. Remaining non-throwing functions aren't marked as
`noexcept` as that wasn't our practice nor is common in our codebase. On
the other hand, if we continue enforcing the documentation of thrown
exceptions, perhaps we should start using `noexcept`.
Reviewers: mferencevic, ipaljak
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2350
Summary:
This makes Gid the same as the one in storage/v2. Before they can be
merge into one implementation, we probably want to have a similar
transition for remaining ID types.
Depends on D2346
Reviewers: mferencevic, ipaljak
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2347
Summary:
It never made sense that a global ID is its own namespace in the storage
directory tree.
Reviewers: mferencevic, ipaljak
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2346
Summary:
This effectively replaces the old PropertyValue implementation from the
one in storage/v2
Depends on D2333
Reviewers: mferencevic, ipaljak
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2335
Summary:
There's a possible race condition where we add a deleted vertex into
index and garbage collection removes it from main storage before indices are
cleaned-up.
Reviewers: mferencevic, teon.banek
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2314
Summary:
Utils now contain a BasicResult implementation which supports different
types of error. This will make it useful for other parts of the code as
well as during the transition from old to new storage.
Reviewers: mtomic, msantl, mferencevic
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2291
Summary:
The documentation includes `std` exceptions like `std::bad_alloc` or
`std::system_error`, for which there's probably nothing we can do. This
may seem unnecessary, but it will be really helpful when writing the C
API for interfacing with custom modules and plugins, as well as when
switching to storage v2 API.
In general, we should start updating the documentation of functions
which may throw exceptions. This ought to be enforced in code review, so
that the implementation and documentation are kept in sync.
Reviewers: mferencevic, mtomic, msantl
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2288
Summary:
This ought to simplify the code which needs to work with any kind of
vertex iteration, be it through an index store or regular.
Reviewers: mtomic, mferencevic
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2258
Summary: this will make GC for indices easier
Reviewers: teon.banek, mferencevic
Reviewed By: teon.banek, mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2223
Summary:
`std::unordered_map` is 56 bytes in size, `std::map` is 48 bytes in size.
Also, `std::map` doesn't require the key type to be hashable.
Reviewers: mtomic, teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2218
Summary:
The first 2 tuple elements are redundant as they are available through
EdgeAccessor and they needlessly complicate the usage of the API.
Reviewers: mtomic, mferencevic
Reviewed By: mtomic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2200
Summary:
`lock_guard` is holding vertex lock while we're deleting the vertex,
and then it might try to unlock it in its destructor and access freed memory.
Reviewers: teon.banek, mferencevic
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2192
Summary:
This change implements full edges support in storage v2. Edges can be created
and deleted. Support for detach-deleting vertices is added and regular vertex
deletion verifies existance of edges.
Reviewers: mtomic, teon.banek
Reviewed By: mtomic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2180
Summary:
We forgot to update `modified_vertices` in the case when the vertex
has an empty version chain. It didn't manifest before because it was impossible
for a vertex to have an empty version chain without garbage collection.
Reviewers: mferencevic, teon.banek
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2154
Summary:
We forgot to add the newly created vertex into `modified_vertices`
list.
Reviewers: teon.banek, mferencevic
Reviewed By: mferencevic
Differential Revision: https://phabricator.memgraph.io/D2153
Summary:
Initial implementation of new storage engine. It implements snapshot isolation
for transactions. All changes in the database are stored as deltas instead of
making full copies. Currently, the storage supports full transaction
functionality (commit, abort, command advancement). Also, support has been
implemented only for vertices that have only labels.
Reviewers: teon.banek, mtomic
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2138
Summary:
HA should now support constraints in the same way the SM version does.
I only tested this thing manually, but I plan to add a new integration test for
this also.
Reviewers: ipaljak, vkasljevic, mferencevic
Reviewed By: ipaljak, mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2083
Summary:
Preparing unique constraint code to be implemented in HA. To do so, I'm
moving everything to `stograge/common/` folder. I also added a new header,
`gid.hpp` which does a `ifdef` include of the correct `gid.hpp` based on the
product.
Reviewers: ipaljak, mferencevic, vkasljevic, teon.banek
Reviewed By: mferencevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2079
Summary:
There will be a lot of leftover files, execute the following commands inside
`src/` to remove them:
```
git clean -xf
rm -r rpc/ storage/single_node_ha/rpc/
```
Reviewers: teon.banek
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2011
Summary:
Manually call `CompactRange` on KVStore (rocksDB) to free disk space
upon Raft log compaction.
Raft log takes surprisingly large amount of disk space (1MB for 1000 entries) so
we need to free disk space as we compact the log into snapshot.
When `log_size_snapshot_threshold` set to `5000` the disk usage of the
`durability_dir` goes from `4.8 MB` to `240 KB`.
Reviewers: ipaljak
Reviewed By: ipaljak
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1939
Summary:
This is still in progress.
As reported in
https://app.asana.com/0/743890251333732/971034572323525/f
memgraph distributed fails when the snapshot that it tries to recover from is
invalid. Instead of inheritance of `StorageGc` this diff adds composition and we
don't try to register a rpc server after the initialization.
Reviewers: ipaljak, vkasljevic, mtomic
Reviewed By: vkasljevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1930
Summary:
Same as `UniqueLabelPropertyConstratint` except it works with multiple properties.
Because of that it is a bit more complex and slower.
Reviewers: msantl, ipaljak
Reviewed By: msantl
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1926
Summary:
It seems that older clang versions erroneously accept modification of
constant pointers, this is a quick hack which resolves the issue on new
clang versions.
None of the const methods are really const and should not be marked as
such. This whole accessor thing is just a steaming pile of crap and
should be rewritten from scratch.
Reviewers: vkasljevic, msantl
Reviewed By: vkasljevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1922
Summary:
Case with existence constraints is about 8-9% slower then case without
existence constraints. Before this diff that difference was about 15-16%.
Reviewers: msantl, ipaljak
Reviewed By: ipaljak
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1917
Summary:
UniqueLabelPropertyConstraint defines label + property restriction on vertices.
Label + Property + PropertyValue for that property must be unique at any given moment.
Reviewers: msantl, ipaljak
Reviewed By: msantl
Subscribers: mferencevic, pullbot
Differential Revision: https://phabricator.memgraph.io/D1884
Summary:
`EdgesIterable` is used for iterating over Edges in distributed memgraph. Because of lru cache there is a possibility of data getting evicted as someone iterates over it.
To prevent that `EdgesIterable` will lock that data and release it when it's deconstructed.
Reviewers: msantl
Reviewed By: msantl
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1868
Summary:
CachedDataLock is necessary for lru cache as remote data is no longer
persistent. Most methods internally handle this, but for methods that
return pointers or references to remote data, we need to manually
lock data.
Reviewers: msantl, ipaljak
Reviewed By: msantl
Subscribers: teon.banek, pullbot
Differential Revision: https://phabricator.memgraph.io/D1869
Summary:
Existence constraint ensures that all nodes with certain label have a certain property.
`ExistenceRule` defines label -> properties rule and `ExistenceConstraints` manages all
constraints.
Reviewers: msantl, ipaljak, teon.banek, mferencevic
Reviewed By: msantl, teon.banek, mferencevic
Subscribers: mferencevic, pullbot
Differential Revision: https://phabricator.memgraph.io/D1797
Summary:
RecordAccessor doesn't implement `operator<`, so it doesn't make sense
to have it inherit TotalOrdering.
Reviewers: mferencevic, msantl, vkasljevic
Reviewed By: vkasljevic
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1866
Summary:
`Edges` class didn't properly filter edges when given both edge type
and destination arguments, which causes weird bugs in query execution (wrong
edge getting matched in `Expand` with existing node flag set). This is probably
because we didn't support using both filters at the same time, but the API and
documentation for `VertexAccessor::in` and `VertexAccessor::out` functions
didn't reflect that.
Reviewers: teon.banek, msantl
Reviewed By: msantl
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1796
Summary:
This is just the first diff that tries to wire the raft protocol into
memgraph.
In this diff I'm introducing transaction engine reset functionality. I also
introduced `RaftInterface` which should be used wherever someone wants to access
Raft from Memgraph.
For design decisions see the feature spec.
Reviewers: ipaljak, teon.banek
Reviewed By: ipaljak
Subscribers: pullbot, teon.banek
Differential Revision: https://phabricator.memgraph.io/D1758
Summary:
GraphDb now has GetStorageStat method that returns live view to
object containing vertex_count, edge_count and avg_degree().
Stat is updated on each garbage collection run and represents number of
objects that are visible to any transaction.
Reviewers: teon.banek, msantl, ipaljak
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1731
Summary:
Since we need to send `StateDelta`s over the wire in HA, we need to be
able to serialize those bad boys.
This diff hopefully does this the right way.
Reviewers: teon.banek, mferencevic, ipaljak
Reviewed By: teon.banek
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D1725
