memgraph/CHANGELOG.md

Change Log

Future

TODO: Don't forget to add items on the fly.

v1.3.0

Breaking Changes

• Added extra information in durability files to support replication, making it incompatible with the durability files generated by older versions of Memgraph. Even though the replication is an Enterprise feature, the files are compatible with the Community version.

Major Features and Improvements

• Added support for data replication across a cluster of Memgraph instances. Supported instance types are MAIN and REPLICA. Supported replication modes are SYNC (all SYNC REPLICAS have to receive data before the MAIN can commit the transaction), ASYNC (MAIN doesn't care if data is replicated), SYNC WITH TIMEOUT (MAIN will wait for REPLICAS within the given timeout period, after timout, replication isn't aborted but the replication demotes the REPLICA to the ASYNC mode).
• Added support for query type deduction. Possible query types are r (read), w (write), rw (read-write). The query type is returned as a part of the summary.
• Improved logging capabilities by introducing granular logging levels. Added new flag, --log-level, which specifies the minimum log level that will be printed. E.g., it's possible to print incoming queries or Bolt server states.
• Added ability to lock the storage data directory by executing the LOCK DATA DIRECTORY; query which delays the deletion of the files contained in the data directory. The data directory can be unlocked again by executing the UNLOCK DATA DIRECTORY; query.

Bug Fixes and Other Changes

• Added cleanup of query executions if not in an explicit transaction.
• Fix RPC dangling reference.

v1.2.0

Breaking Changes

• SSL is disabled by default (--bolt-cert-file and --bolt-key-file are empty). This change might only affect the client connection configuration.

Major Features and Improvements

• Added support for Bolt v4.0 and v4.1.
• Added mgp_networkx.py as an alternative implementation of NetworkX graph objects, which is useful to use Memgraph data from NetworkX algorithms optimally.
• Added nxalg.py query module as a proxy to NetworkX algorithms.
• Added plan optimization to use a label-property index where the property is not null. As a result, the query engine, instead of scanning all elements and applying the filter, performs a label-property index lookup when possible.

Bug Fixes and Other Changes

• Fixed Cypher ID function Null handling. When the ID function receives Null, it will also return Null.
• Fixed bug that caused random crashes in SSL communication on platforms that use older versions of OpenSSL (< 1.1) by adding proper multi-threading handling.
• Fix DISCARD message handling. The query is now executed before discarding the results.

v1.1.0

Major Features and Improvements

• Properties in nodes and edges are now stored encoded and compressed. This change significantly reduces memory usage. Depending on the specific dataset, total memory usage can be reduced up to 50%.
• Added support for rescanning query modules. Previously, the query modules directory was scanned only upon startup. Now it is scanned each time the user requests to load a query module. The functions used to load the query modules were renamed to mg.load() and mg.load_all() (from mg.reload() and mg.reload_all()).
• Improved execution performance of queries that have an IN list filter by using label+property indices. Example: MATCH (n:Label) WHERE n.property IN [] ...
• Added support for ANY and NONE openCypher functions. Previously, only ALL and SINGLE functions were implemented.

Bug Fixes and Other Changes

• Fixed invalid paths returned by variable expansion when the starting node and destination node used the same symbol. Example: MATCH path = (n:Person {name: "John"})-[:KNOWS*]->(n) RETURN path
• Improved semantics of ALL and SINGLE functions to be consistent with openCypher when handling lists with Nulls.
• SHOW CONSTRAINT INFO now returns property names as a list for unique constraints.
• Escaped label/property/edgetype names in DUMP DATABASE to support names with spaces in them.
• Fixed handling of DUMP DATABASE queries in multi-command transactions (BEGIN, ..., COMMIT).
• Fixed handling of various query types in explicit transactions. For example, constraints were allowed to be created in multi-command transactions (BEGIN, ..., COMMIT) but that isn't a transactional operation and as such can't be allowed in multi-command transactions.
• Fixed integer overflow bugs in COUNT, LIMIT and SKIP.
• Fixed integer overflow bugs in weighted shortest path expansions.
• Fixed various other integer overflow bugs in query execution.
• Added Marvel Comic Universe tutorial.
• Added FootballTransfers tutorial.

v1.0.0

Major Features and Improvements

• [Enterprise Ed.] Exposed authentication username/rolename regex as a flag (--auth-user-or-role-name-regex).
• [Enterprise Ed.] Improved auth module error handling and added support for relative paths.
• Added support for Python query modules. This release of Memgraph supports query modules written using the already existing C API and the new Python API.
• Added support for unique constraints. The unique constraint is created with a label and one or more properties.
• Implemented support for importing CSV files (mg_import_csv). The importer is compatible with the Neo4j batch CSV importer.
• Snapshot and write-ahead log format changed (backward compatible with v0.50).
• Vertices looked up by their openCypher ID (MATCH (n) WHERE ID(n) = ...) will now find the node in O(logn) instead of O(n).
• Improved planning of BFS expansion, a faster, specific approach is now favored instead of a ScanAll+Filter operation.
• Added syntax for limiting memory of CALL.
• Exposed server name that should be used for Bolt handshake as flag (--bolt-server-name-for-init).
• Added several more functions to the query module C API.
• Implemented a storage locking mechanism that prevents the user from concurrently starting two Memgraph instances with the same data directory.

Bug Fixes and Other Changes

• [Enterprise Ed.] Fixed a bug that crashed the database when granting privileges to a user.
• [Enterprise Ed.] Improved Louvain algorithm for community detection.
• Type of variable expansion is now printed in EXPLAIN (e.g. ExpandVariable, STShortestPath, BFSExpand, WeightedShortestPath).
• Correctly display CALL in EXPLAIN output.
• Correctly delimit arguments when printing the signature of a query module.
• Fixed a planning issue when CALL preceded filtering.
• Fixed spelling mistakes in the storage durability module.
• Fixed storage GC indices/constraints subtle race condition.
• Reduced memory allocations in storage API and indices.
• Memgraph version is now outputted to stdout when Memgraph is started.
• Improved RPM packaging.
• Reduced number of errors reported in production log when loading query modules.
• Removed early access wording from the Community Offering license.

v0.50.0

Breaking Changes

• [Enterprise Ed.] Remove support for Kafka streams.
• Snapshot and write-ahead log format changed (not backward compatible).
• Removed support for unique constraints.
• Label indices aren't created automatically, create them explicitly instead.
• Renamed several database flags. Please see the configuration file for a list of current flags.

Major Features and Improvements

• [Enterprise Ed.] Add support for auth module.
• [Enterprise Ed.] LDAP support migrated to auth module.
• Implemented new graph storage engine.
• Add support for disabling properties on edges.
• Add support for existence constraints.
• Add support for custom openCypher procedures using a C API.
• Support loading query modules implementing read-only procedures.
• Add CALL <procedure> YIELD <result> syntax for invoking loaded procedures.
• Add CREATE INDEX ON :Label for creating label indices.
• Add DROP INDEX ON :Label for dropping label indices.
• Add DUMP DATABASE clause to openCypher.
• Add functions for treating character strings as byte strings.

Bug Fixes and Other Changes

• Fix several memory management bugs.
• Reduce memory usage in query execution.
• Fix bug that crashes the database when EXPLAIN is used.

v0.15.0

Breaking Changes

• Snapshot and write-ahead log format changed (not backward compatible).
• indexInfo() function replaced with SHOW INDEX INFO syntax.
• Removed support for unique index. Use unique constraints instead.
• CREATE UNIQUE INDEX ON :label (property) replaced with CREATE CONSTRAINT ON (n:label) ASSERT n.property IS UNIQUE.
• Changed semantics for COUNTER openCypher function.

Major Features and Improvements

• [Enterprise Ed.] Add new privilege, STATS for accessing storage info.
• [Enterprise Ed.] LDAP authentication and authorization support.
• [Enterprise Ed.] Add audit logging feature.
• Add multiple properties unique constraint which replace unique indices.
• Add SHOW STORAGE INFO feature.
• Add PROFILE clause to openCypher.
• Add CREATE CONSTRAINT clause to openCypher.
• Add DROP CONSTRAINT clause to openCypher.
• Add SHOW CONSTRAINT INFO feature.
• Add uniformSample function to openCypher.
• Add regex matching to openCypher.

Bug Fixes and Other Changes

• Fix bug in explicit transaction handling.
• Fix bug in edge filtering by edge type and destination.
• Fix bug in query comment parsing.
• Fix bug in query symbol table.
• Fix OpenSSL memory leaks.
• Make authentication case insensitive.
• Remove COALESCE function.
• Add movie tutorial.
• Add backpacking tutorial.

v0.14.0

Breaking Changes

• Write-ahead log format changed (not backward compatible).

Major Features and Improvements

• [Enterprise Ed.] Reduce memory usage in distributed usage.
• Add DROP INDEX feature.
• Improve SSL error messages.

Bug Fixes and Other Changes

• [Enterprise Ed.] Fix issues with reading and writing in a distributed query.
• Correctly handle an edge case with unique constraint checks.
• Fix a minor issue with mg_import_csv.
• Fix an issue with EXPLAIN.

v0.13.0

Breaking Changes

• Write-ahead log format changed (not backward compatible).
• Snapshot format changed (not backward compatible).

Major Features and Improvements

• [Enterprise Ed.] Authentication and authorization support.
• [Enterprise Ed.] Kafka integration.
• [Enterprise Ed.] Support dynamic worker addition in distributed.
• Reduce memory usage and improve overall performance.
• Add CREATE UNIQUE INDEX clause to openCypher.
• Add EXPLAIN clause to openCypher.
• Add inDegree and outDegree functions to openCypher.
• Improve BFS performance when both endpoints are known.
• Add new node-label, relationship-type and quote options to mg_import_csv tool.
• Reduce memory usage of mg_import_csv.

Bug Fixes and Other Changes

• [Enterprise Ed.] Fix an edge case in distributed index creation.
• [Enterprise Ed.] Fix issues with Cartesian in distributed queries.
• Correctly handle large messages in Bolt protocol.
• Fix issues when handling explicitly started transactions in queries.
• Allow openCypher keywords to be used as variable names.
• Revise and make user visible error messages consistent.
• Improve aborting time consuming execution.

v0.12.0

Breaking Changes

• Snapshot format changed (not backward compatible).

Major Features and Improvements

• Improved Id Cypher function.
• Added string functions to openCypher (lTrim, left, rTrim, replace, reverse, right, split, substring, toLower, toUpper, trim).
• Added timestamp function to openCypher.
• Added support for dynamic property access with [] operator.

v0.11.0

Major Features and Improvements

• [Enterprise Ed.] Improve Cartesian support in distributed queries.
• [Enterprise Ed.] Improve distributed execution of BFS.
• [Enterprise Ed.] Dynamic graph partitioner added.
• Static nodes/edges id generators exposed through the Id Cypher function.
• Properties on disk added.
• Telemetry added.
• SSL support added.
• toString function added.

Bug Fixes and Other Changes

• Document issues with Docker on OS X.
• Add BFS and Dijkstra's algorithm examples to documentation.

v0.10.0

Breaking Changes

• Snapshot format changed (not backward compatible).

Major Features and Improvements

• [Enterprise Ed.] Distributed storage and execution.
• reduce and single functions added to openCypher.
• wShortest edge expansion added to openCypher.
• Support packaging RPM on CentOS 7.

Bug Fixes and Other Changes

• Report an error if updating a deleted element.
• Log an error if reading info on available memory fails.
• Fix a bug when MATCH would stop matching if a result was empty, but later results still contain data to be matched. The simplest case of this was the query: UNWIND [1,2,3] AS x MATCH (n :Label {prop: x}) RETURN n. If there was no node (:Label {prop: 1}), then the MATCH wouldn't even try to find for x being 2 or 3.
• Report an error if trying to compare a property value with something that cannot be stored in a property.
• Fix crashes in some obscure cases.
• Commit log automatically garbage collected.
• Add minor performance improvements.

v0.9.0

Breaking Changes

• Snapshot format changed (not backward compatible).
• Snapshot configuration flags changed, general durability flags added.

Major Features and Improvements

• Write-ahead log added.
• nodes and relationships functions added.
• UNION and UNION ALL is implemented.
• Concurrent index creation is now enabled.

Bug Fixes and Other Changes

v0.8.0

Major Features and Improvements

• CASE construct (without aggregations).
• Named path support added.
• Maps can now be stored as node/edge properties.
• Map indexing supported.
• rand function added.
• assert function added.
• counter and counterSet functions added.
• indexInfo function added.
• collect aggregation now supports Map collection.
• Changed the BFS syntax.

Bug Fixes and Other Changes

• Use \u to specify 4 digit codepoint and \U for 8 digit
• Keywords appearing in header (named expressions) keep original case.
• Our Bolt protocol implementation is now completely compatible with the protocol version 1 specification. (https://boltprotocol.org/v1/)
• Added a log warning when running out of memory and the memory_warning_threshold flag
• Edges are no longer additionally filtered after expansion.

v0.7.0

Major Features and Improvements

• Variable length path MATCH.
• Explicitly started transactions (multi-query transactions).
• Map literal.
• Query parameters (except for parameters in place of property maps).
• all function in openCypher.
• degree function in openCypher.
• User specified transaction execution timeout.

Bug Fixes and Other Changes

• Concurrent BUILD INDEX deadlock now returns an error to the client.
• A MATCH preceeded by OPTIONAL MATCH expansion inconsistencies.
• High concurrency Antlr parsing bug.
• Indexing improvements.
• Query stripping and caching speedups.

v0.6.0

Major Features and Improvements

• AST caching.
• Label + property index support.
• Different logging setup & format.

v0.5.0

Major Features and Improvements

• Use label indexes to speed up querying.
• Generate multiple query plans and use the cost estimator to select the best.
• Snapshots & Recovery.
• Abandon old yaml configuration and migrate to gflags.
• Query stripping & AST caching support.

Bug Fixes and Other Changes

• Fixed race condition in MVCC. Hints exp+aborted race condition prevented.
• Fixed conceptual bug in MVCC GC. Evaluate old records w.r.t. the oldest. transaction's id AND snapshot.
• User friendly error messages thrown from the query engine.

Build 837

Bug Fixes and Other Changes

• List indexing supported with preceeding IN (for example in query RETURN 1 IN [[1,2]][0]).

Build 825

Major Features and Improvements

• RETURN , count(), OPTIONAL MATCH, UNWIND, DISTINCT (except DISTINCT in aggregate functions), list indexing and slicing, escaped labels, IN LIST operator, range function.

Bug Fixes and Other Changes

• TCP_NODELAY -> import should be faster.
• Clear hint bits.

Build 783

Major Features and Improvements

• SKIP, LIMIT, ORDER BY.
• Math functions.
• Initial support for MERGE clause.

Bug Fixes and Other Changes

• Unhandled Lock Timeout Exception.

Build 755

Major Features and Improvements

• MATCH, CREATE, WHERE, SET, REMOVE, DELETE.