Release Notes

Current release versions can be downloaded at

Known issue: If a query contains more than 32k positional parameters for Postgres, this can cause a query to fail. This is due to a limit in the underlying JDBC driver for Postgres. Postgres itself is limited to 64k positional parameters. To resolve, ensure that no more than 32k positional parameters are used.

Release build (April 5, 2021)

  1. Improved compatibility with delayed transactions;
  2. Resolved issue where commands like commit and rollback would result in a sql log entry for the previous SQL command;
  3. Added logic to trim prepared statements on a connection to no more than 2000 prepares to prevent memory overflow.  Ruby trims to 1000, and Java to 256, so this should be plenty for most environments;
  4. Added logic to forget the last used parameters of a prepared statement after use, to reduce memory overhead;
  5. Added support for hstore types in binary format for Postgres;
  6. Added better support for commands like drop, alter, etc. that do not actually touch a table, but other metadata.  These will be flagged as modification queries, so that read/write split doesn’t send them to the wrong server;
  7. Added to the sql server pool logic a default resetQuery of exec sp_reset_connection;
  8. Improved SQL parsing for many different query formats to improve table extraction;
  9. Avoid using the /tmp directory created by tomcat for temporary file uploads, as centos and derived systems clean up directories over time, and can break the update and other logic;
  10. Added a filter on keys used by Heimdall in external grid caches to prevent non-heimdall keys from being tracked in the cache logic, adding to memory overhead;
  11. Added a limit of 10x the number of objects specified in the cache object limit (if set) for tracking remote keys, again to limit memory usage;
  12. Fix various issues with prepared SQL statements that include ? as part of the content, which impacted java prepared statement formats;
  13. Improved temporary table detection logic, in particular for SQL Server;
  14. Improvement in TLS handling, including disabling tls 1.3 with SQL Server, as it doesn’t support it yet, and trying to negotiate it with SQL server libraries often breaks them;
  15. Improved accuracy of Prepared statement performance in the Analytics tab;
  16. Prevent alerts from prior to a clean restart of the management server from showing back up after restart.

Release build (Feb 27, 2021)

  1. Critical: Fix a problem with MySQL when using prepared statements and read/write split (or anything that expands the prepared query to raw SQL) introduced in the last release build. This also impacted SQL logging in some cases as well;
  2. Critical: Disable TLS 1.3 only for SQL Server–clients often will attempt to negotiate tls 1.3 if the proxy supports it, but they aren’t tested with tls 1.3, and end up breaking. SQL Server itself doesn’t support TLS 1.3; This would be observed as a connection hang on any attempt to connect. This was triggered by tls 1.3 being backported by Oracle into Java 8 in late 2020, which is used by default by Heimdall;
  3. Change the downloaded log filename format for .zip files to include yyyyMMddHHmm, previously it was using minutes for the month position;
  4. Add logging of full query hash in debug logs, along with logging some other error conditions for TLS, etc;
  5. Resolved issue where a rule disabling multiplexing was not taking effect due to a rule processing optimization;
  6. Resolved an issue with insert queries with more than 500k fields inserted (across all rows) due to limit in regex processing that limited the number of capture groups that could be created;
  7. Removed a limit of 1024k for a single Postgres packet on query read, which limited the size of an insert that could be done as a single operation;
  8. Added DML detection for generic create and drop commands for non-table oriented SQL. This prevents such queries from being directed to a read node with read/write split;
  9. Ignore quotes and question marks in comments when looking for unbalanced quotes or parameters to fill in for SQL expansion;
  10. Add further compatibility with the PHP PDO drivers for MySQL;
  11. Correct an issue where rows read was not reported correctly for SQL Server at the protocol level;
  12. Resolved issue where proxy auth being disabled for Postgres still resulted in Proxy auth being enabled in the resulting wizard configuration.

Release Build (Feb 13, 2021)

  1. Minor usability improvements in the wizard
  2. Detect Azure marketplace deployments for licensing
  3. Improved TLS handling and error logging
  4. Support binary uploads with prepared queries for PDO MySQL (PHP)
  5. Improved handling of temporary tables
  6. Improve manual update process in low memory situations
  7. Resolve issue with the proxy where it wouldn’t update the code on a restart (requires updating the script)
  8. Add example configuration for PHP’s MySQL PDO to extract the certificate from the keystore
  9. Properly handle table names/aliases with question marks when expanding prepared queries for read/write split or transformation.

Release Build (Jan 24, 2021)

  1. Resolve issue with Data Direct MySQL drivers that prevented queries from completing execution;
  2. Improved logic for Postgres failovers in the Azure cloud environment in the parsing of the replication connect string and to support the hostaddr option;
  3. Corrected some cases where the defaultCatalog option was not being used properly to establish connections;
  4. Resolved an infinite loop that could occur if using TLS and the client connection was disconnected unexpectedly;
  5. Updated the default included driver database and driver names;
  6. Remove the creation of new configuration files if the update server API was used;
  7. Updated Hazelcast to 4.1.1 and include yaml configuration file support;
  8. Resolve issue with internal commands like show pool with MS-SQL Server proxy configurations;
  9. Added an option to allow recursive transform calls, to allow the transformation to be applied more than once on a single query;
  10. Resolve a memory leak when connections were dropped by the client under very high new connection/second loads;
  11. Improved logging (as normal).

Previous year’s release notes can be found at: