Engine settings

List of Querona’s engine configuration options is a follows:

Configuration option	Default value	Requires restart?	Description
SQL Server edition emulation	SQL Azure	Yes	The following emulation options are supported: SQL Azure (default), SQL Server Enterprise Edition 2012 and SQL Server Enterprise Edition 2022.
Heartbeat interval seconds	10	No	The interval of a heartbeat in seconds.
Heartbeats missed limit	6	No	Max consecutive missed heartbeats before cluster failure detection.
Max prepared statements in connection	200	No	Max prepared statements per connection.
Plan cache cleanup interval [second]	10	No	Interval for evicting stale or expired query execution plans.
Cached execution plan unused max age [seconds]	3600	No	Max age of unused cached execution plans.
Execution plan cache size	1000	No	Max execution plans in cache.
Pool size [MB]	256	No	Memory pool size in megabytes.
Data transfer to federator limit [B]	52428800	No	Maximum data size to be sent to a data source for pushdown.
Min worker threads	100	No	Minimal count of worker threads in a thread pool.
Min completion port threads	100	No	Minimal count of completion port threads in a pool.
Max worker threads	32767	No	Maximum count of worker threads in a thread pool.
Max completion port threads	1000	No	Maximum count of completion port threads in a pool.
Max statements stored	1000	No	Maximum count of stored statements.
Row count of tables without statistics	10000000	No	Default rowcount that query optimizer will use for tables without statistics. Default value of 10.000.000 is optimized for analytical workloads. It is strongly recommended to adjust this value to match your environment.
Primary host connects to all instances on start	false	No	True, in a cluster environment, forces Querona’s Primary Instance to connect to all known instances during boot.
JVM Custom JAVA_HOME	empty	Yes	Querona automatically detects a supported JVM, but if a specific JVM has to be used, an explicit override of JAVA_HOME environment variable can be provided here.
JVM Startup Params	empty	Yes	Custom JVM startup parameters, for example, -XX:G1PeriodicGCInterval=5000.
Built-in JVM classpath (csv)	empty	Yes	A comma-separated list of paths to folders where Querona should look for JDBC drivers and load during boot all that it finds.
TDS char collation for returned character types	SQL_Latin1_General_CP1_CI_AS	No	Collation used by TDS for all returned string types.
Enable windows authentication	false	Yes	When enabled, users can logon to Web GUI using Windows Integrated authentication.
XQuery cache buffer size	500	No	Max number of compiled XQuery expressions cached for XML data type methods (value()/exist()/query()/nodes()). 0 disables the cache.

TDS Collation for Returned String Types

This setting controls collation used by TDS for all returned string types. Default value is SQL_Latin1_General_CP1_CI_AS. It does not change collations in source systems and does not alter stored provider data. The legacy text and ntext types are an exception: text is always returned in the collation’s single-byte code page and ntext is always UTF-16, so neither reflects a UTF-8 or supplementary-character (SC) collation variant. The standard char, varchar, nchar and nvarchar types are not affected.

Experimental settings

Configuration option	Default value	Requires restart?	Description
TOP push-down over UNION clause	false	No	When enabled, allows Querona to push a TOP clause down directly to a provider if a FROM clause grabs rows from a view/sub-select w/ UNION operator.
Predicate push-down over UNION clause	false	No	When enabled, allows Querona to push-down predicated through the UNION clause(s).
FOR JSON AUTO with JOIN statements	false	No	When enabled, allows for ‘FOR JSON AUTO’ clause with JOIN statements on SQL Server.