This PR introduces READ COMMITTED and READ UNCOMMITTED isolation levels.
The isolation level can be set with a config or with a query for different scopes.
* Throw OOMException while creating vertices and edges
* Throw on indices creation
* Throw on setting a property
* Throw oom exception while recovering
* Throw exception when query engine asks for extra memory
* Block out of memor exception during skip list GC
* Define additional commit log constructor which takes an oldest active id
* Delay commit log construction until the recovery process is finished
* Add test for commit log with initial id
* Silence the macro redefinition warning
* Set state to invalid after exception
* Add proper locking
* Start background replicating only if in valid state
* Freeze transaction timestamp on replica
* Timeout fixes
* Fix Jepsen run script
* Disable perf checker and enable nemesis
* Add documentation for some chunks of code
* Decrease timeout so main doesn't hang on network partitions too long
* Add config for replication client/server
* Add SSL to replication
* Add semi-sync replication
* Expose necessary information about replication
* Thread pool fix
* Set BasicResult value type to void
* Add basic communication process using commit timestamp
* Add file number to req
* Add proper recovery handling
* Allow loading of WALs with same seq num
* Allow always desired commit timestamp
* Set replica timestamp for operation
* Mark non-transactional timestamp as finished
* Add file transfer over RPC
* Snapshot transfer implementation
* Allow snapshot creation only for MAIN instances
* Replica and main can have replication clients
* Use only snapshots and WALs that are from the Main storage
* Add flush lock and expose buffer
* Add fstat for file size and TryFlushing method
* Use lseek for size
Co-authored-by: Antonio Andelic <antonio.andelic@memgraph.io>
* Add tests for multiple clients
* Use variant for RPC server and clients
* Using synchronized list for replication clients, extracted variant access to a function
* Set MAIN as default, add unregister function, add a name for replication clients
* Use the regular list for clients
* Use test fixture so storage directory is cleaned
* Use seq_cst for replication_state
Co-authored-by: Antonio Andelic <antonio.andelic@memgraph.io>
This implements the initial version of synchronous replication.
Currently, only one replica is supported and that isn't configurable.
To run the main instance use the following command:
```
./memgraph \
--main \
--data-directory main-data \
--storage-properties-on-edges \
--storage-wal-enabled \
--storage-snapshot-interval-sec 300
```
To run the replica instance use the following command:
```
./memgraph \
--replica \
--data-directory replica-data \
--storage-properties-on-edges \
--bolt-port 7688
```
You can then write/read data to Bolt port 7687 (the main instance) and also you
can read the data from the replica instance using Bolt port 7688.
NOTE: The main instance *must* be started without any data and the replica
*must* be started before any data is added to the main instance.
* Add basic synchronous replication test
* Using RWLock for replication stuff
Co-authored-by: Matej Ferencevic <matej.ferencevic@memgraph.io>
Co-authored-by: Antonio Andelic <antonio.andelic@memgraph.io>
Summary:
This diff improves the performance of `PropertyStore` with two main
techniques:
First:
`PropertyValue` has a very expensive constructor and destructor. The
`PropertyValue` was previously passed as a return value from many functions
wrapped in a `std::optional`. That caused the `PropertyValue`
constructor/destructor to be called for each intermediary value that was passed
between functions. This diff changes the functions to return a `bool` value
that imitates the `std::optional` "emptyness" flag and the `PropertyValue` is
modified using a pointer to it so that its constructor/destructor is called
only once.
Second:
The `PropertyStore` buffer was previously iterated through at least twice.
First to determine the exact position of the encoded property and then to
actually decode the property. This diff combines the two passes into a single
pass so that the property is immediately loaded if it is found.
Reviewers: buda
Reviewed By: buda
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2766
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
