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Version: 2.0.0

Changelog

v2.0.0 - Oct 5, 2021​

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Breaking Changes​

  • Changed the timestamp() function to return microseconds instead of milliseconds.
  • Most of the query modules C API functions are changed to return a mgp_error as a more fine-grained way of error reporting. The only exceptions are the functions that free allocated memory (mgp_free and mgp_global_free) and destroy objects (mgp_value_destroy, mgp_list_destory, etc.) which remain the same.
  • The first user created using the CREATE USER query will have all the privileges granted to him. Previously, you could've locked yourself out of Memgraph by creating a user and immediately disconnecting.

Major Features and Improvements​

  • Added support for temporal types, a feature that allows the user to manipulate and store time related data in the graph. For more information take a look at the reference guide
  • Added support for parameters with CREATE clause in the following form: CREATE (n $param).
  • Introduced settings to Memgraph that can be modified during runtime. You can check out more details here.
  • Added writeable procedure support, so procedures can modify the graph by creating and deleting vertices and edges, modifying the labels of vertices or setting the properties of vertices and edges.

Bug Fixes​

  • Fixed planning of queries with MERGE clause. If a previously defined symbol is used as property value inside the MERGE clause, the planner will correctly use the label-property index if present.
  • Unused memory is correctly returned to OS when FREE MEMORY query is used. Before, Memgraph would free up the memory internally and not return it to the OS. Because of that Memgraph could allocate more memory from the OS than it's allowed.
  • Fixed recovery from durability files. Because of a wrong check, Memgraph could crash and leave the durability files in an invalid state making recovery not possible.
  • Fixed usage of execute keyword in queries. Because of the special way we handle the EXECUTE keyword from the CREATE TRIGGER query using that same keyword in other contexts caused Memgraph to crash.

v1.6.1 - Jul 24, 2021​

Major Features and Improvements​

  • Added proper privilege checks for queries executed by triggers and stream transformations.

Bug Fixes​

  • Fixed error handling in streams to make restarting streams possible after failing. The issue is caused by not rolling back the transaction in which the query failed, so when the stream was restarted and tried to process the next batch of messages it was still in a transaction, but it tried to start a new one. Now the transaction is rolled back in case of any errors during query execution, so a new transaction can be started during the processing of the next batch of messages.

v1.6.0 - Jul 7, 2021​

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Breaking Changes​

  • Changed the LOCK_PATH permission to DURABILITY.

Major Features and Improvements​

  • Added support for consuming Kafka streams. You can connect Memgraph to a Kafka cluster and run queries based on the messages received. The transformation from Kafka to Cypher queries is done using Transformation Modules, a concept similar to Query Modules. Using our Python and C API, you can easily define functions that analyze Kafka messages and generate different queries based on them. The stream connection can be configured, tested, stopped, started, checked, and dropped.
  • Introduced global allocators for Query Modules using C API, so the data can be preserved between multiple runs of the same procedure.
  • Introduced new isolation levels, READ COMMITTED and READ_UNCOMMITTED. The isolation level can be set with a config. Also, you can set the isolation level for a certain session or the next transaction. The names of the isolation levels should be self-explanatory, unlike the SNAPSHOT ISOLATION which is still the default isolation level.
  • The query timeouts are now triggered using a different method. Before, we used the TSC to measure the execution time. Unfortunately, this proved unreliable for certain CPUs (AMD Ryzen 7 and M1), which caused queries to timeout almost instantly. We switched to POSIX timer which should work on every hardware, while not affecting the performance.
  • Added a config, allow-load-csv, with which you can disable LOAD CSV clause. LOAD CSV can read and display data from any file on the system which could be insecure for some systems. Because of that, we added a config that allows you to disable that clause in every case.
  • Added CREATE SNAPSHOT query. Snapshots are created every few minutes, using this query you can trigger snapshot creation instantly.
  • Increased the default query timeout to 10 minutes. The previous default amount of 3 minutes proved too small, especially for queries that use LOAD CSV with a large dataset.

Bug Fixes​

  • Fixed parsing of certain types in Query Modules using Python API.
  • Fixed a concurrency bug for Query Modules using Python API. Running the same procedure from multiple clients caused the Memgraph instance to crash.
  • Fixed restoring triggers that call procedures. Because the triggers were restored before the procedures, the query trigger executes couldn't find the called procedure, which caused the restore to fail. Switching up the order was enough to fix the problem.

v1.5.0 - May 28, 2021​

Major Features and Improvements​

  • Added database triggers. You can now create, delete, and print out triggers that execute Cypher statements. You can create custom actions whenever a node or an edge is created, updated, or deleted. All the triggers are persisted on the disk, so no information is lost between runs.
  • Replaced mg_client with the mgconsole command-line interface, which ships directly with Memgraph. You can now install mgconsole directly on Windows and macOS.

Bug Fixes​

  • Fixed parsing of types for Python procedures for types nested in mgp.List. For example, parsing of mgp.List[mgp.Map] works now.
  • Fixed memory tracking issues. Some of the allocation and deallocation wasn't tracked during the query execution.
  • Fixed reading CSV files that are using CRLF as the newline symbol.
  • Fixed permission issues for LOAD CSV, FREE MEMORY, LOCK DATA DIRECTORY, and replication queries.

v1.4.0 - Apr 2, 2021​

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Breaking Changes​

  • Changed MEMORY LIMIT num (KB|MB) clause in the procedure calls to PROCEDURE MEMORY LIMIT num (KB|MB). The functionality is still the same.

Major Features and Improvements​

  • Added replication to community version.
  • Added support for multiple query modules directories at the same time. You can now define multiple, comma-separated paths to directories from which the modules will be loaded using the --query-modules-directory flag.
  • Added support for programatically reading in data from CSV files through the LOAD CSV clause. We support CSV files with and without a header, the supported dialect being Excel.
  • Added a new flag --memory-limit which enables the user to set the maximum total amount of memory memgraph can allocate during its runtime.
  • Added FREE MEMORY query which tries to free unusued memory chunks in different parts of storage.
  • Added the memory limit and amount of currently allocated bytes in the result of SHOW STORAGE INFO query.
  • Added QUERY MEMORY LIMIT num (KB|MB) to Cypher queries which allows you to limit memory allocation for the entire query. It can be added only at the end of the entire Cypher query.
  • Added logs for the different parts of the recovery process. INFO, DEBUG and TRACE level all contain additional information that is printed out while the recovery is in progress.

Bug Fixes​

  • Fixed garbage collector by correctly marking the oldest current timestamp after the database was recovered using the durability files.
  • Fixed reloading of the modules with changed result names.
  • Fixed profile query to show the correct name of the ScanAll operator variant.

v1.3.0 - Jan 26, 2021​

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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 - Oct 20, 2020​

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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 - Jul 1, 2020​

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 - Apr 3, 2020​

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 - Dec 11, 2019​

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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 - Jul 17, 2019​

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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 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.

v0.14.1 - Jan 22, 2019​

Bug Fixes and Other Changes​

  • Fix bug in explicit transaction handling.
  • Fix bug in edge filtering by edge type and destination.

v0.14.0 - Oct 30, 2018​

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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 - Oct 18, 2018​

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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 - Jul 4, 2018​

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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 - Jun 20, 2018​

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 - Apr 24, 2018​

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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 - Dec 18, 2017​

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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.