Configuration Parameters for HeavyDB

Following are the parameters for runtime settings on HeavyDB. The parameter syntax provides both the implied value and the default value as appropriate. Optional arguments are in square brackets, while implied and default values are in parentheses.

For example, consider allow-loop-joins [=arg(=1)] (=0).

• If you do not use this flag, loop joins are not allowed by default.

• If you provide no arguments, the implied value is 1 (true) (allow-loop-joins).

• If you provide the argument 0, that is the same as the default (allow-loop-joins=0).

• If you provide the argument 1, that is the same as the implied value (allow-loop-joins=1).

Flag	Description	Default Value
allow-cpu-retry [=arg]	Allow the queries that failed on GPU to retry on CPU, even when watchdog is enabled. When watchdog is enabled, most queries that run on GPU and throw a watchdog exception fail. Turn this on to allow queries that fail the watchdog on GPU to retry on CPU. The default behavior is for queries that run out of memory on GPU to throw an error if watchdog is enabled. Watchdog is enabled by default.	TRUE[1]
allow-cpu-kernel-concurrency	Allow for multiple queries to run execution kernels concurrently on CPU. Example: In a system with a number of executor of 4 (controlled by the parameter number-executors) 3+1 (the +1 is depending by the allow-cpu-gpu-kernel-concurrency) can run concurrently in the CPU.	DEFAULT: ON
allow-cpu-gpu-kernel-concurrency	Allow multiple queries to run execution kernels concurrently on CPU while a GPU query is executing. Example: In a system with a number of executor of 4 (controlled by the parameter number-executors), on of the 4 slot can be used to run a GPU query, along with other 3 running on CPU.	DEFAULT: ON
allow-local-auth-fallback [=arg(=1)] (=0)	If SAML or LDAP logins are enabled, and the logins fail, this setting enables authentication based on internally stored login credentials. Command-line tools or other tools that do not support SAML might reject those users from logging in unless this feature is enabled. This allows a user to log in using credentials on the local database.	FALSE[0]
allow-loop-joins [=arg(=1)] (=0)	Enables all join queries to fall back to the loop join implementation. During a loop join, queries loop over all rows from all tables involved in the join, and evaluate the join condition. By default, loop joins are only allowed if the number of rows in the inner table is fewer than the trivial-loop-join-threshold, since loop joins are computationally expensive and run for an extended period. Modifying the trivial-loop-join-threshold is a safer alternative to globally enabling loop joins. You might choose to globally enable loop joins when you have many small tables for which loop join performance has been determined to be acceptable but modifying the trivial join loop threshold would be tedious.	FALSE[0]
allowed-export-paths = ["root_path_1", root_path_2", ...]	Specify a list of allowed root paths that can be used in export operations, such as the COPY TO command. Helps prevent exploitation of security vulnerabilities and prevent server crashes, data breaches, and full remote control of the host machine. For example: allowed-export-paths = ["/heavyai-storage/data/heavyai_export", "/home/centos"] The list of paths must be on the same line as the configuration parameter. Allowed file paths are enforced by default. The default export path (<data directory>/heavyai_export) is allowed by default, and all child paths of that path are allowed. When using commands with other paths, the provided paths must be under an allowed root path. If you try to use a nonallowed path in a COPY TO command, an error response is returned.	N/A
allow-s3-server-privileges	Allow S3 server privileges if IAM user credentials are not provided. Credentials can be specified with environment variables (such as AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and so on), an AWS credentials file, or when running on an EC2 instance, with an IAM role that is attached to the instance.	FALSE[0]
allowed-import-paths = ["root_path_1", "root_path_2", ...]	Specify a list of allowed root paths that can be used in import operations, such as the COPY FROM command. Helps prevent exploitation of security vulnerabilities and prevent server crashes, data breaches, and full remote control of the host machine. For example: allowed-import-paths = ["/heavyai-storage/data/heavyai_import", "/home/centos"] The list of paths must be on the same line as the configuration parameter. Allowed file paths are enforced by default. The default import path (<data directory>/heavyai_import) is allowed by default, and all child paths of that allowed path are allowed. When using commands with other paths, the provided paths must be under an allowed root path. If you try to use a nonallowed path in a COPY FROM command, an error response is returned.	N/A
approx_quantile_buffer arg	Size of a temporary buffer that is used to copy in the data for APPROX_MEDIAN calculation. When full, is sorted before being merged into the internal distribution buffer configured in approx_quantile_centroids.	1000
approx_quantile_centroids arg	Size of the internal buffer used to approximate the distribution of the data for which the APPOX_MEDIAN calculation is taken. The larger the value, the greater the accuracy of the answer.	300
auth-cookie-name arg	Configure the authentication cookie name. If not explicitly set, the default name is oat.	oat
bigint-count [=arg]	Use 64-bit count. Disabled by default because 64-bit integer atomics are slow on GPUs. Enable this setting if you see negative values for a count, indicating overflow. In addition, if your data set has more than 4 billion records, you likely need to enable this setting.	FALSE[0]
bitmap-memory-limitarg	Set the maximum amount of memory (in GB) allocated for APPROX_COUNT_DISTINCT bitmaps per execution kernel (thread or GPU).	8
calcite-max-mem arg	Max memory available to calcite JVM. Change if Calcite reports out-of-memory errors.	1024
calcite-port arg	Calcite port number. Change to avoid collisions with ports already in use.	6279
calcite-service-timeout	Service timeout value, in milliseconds, for communications with Calcite. On databases with large numbers of tables, large numbers of concurrent queries, or many parallel updates and deletes, Calcite might return less quickly. Increasing the timeout value can prevent THRIFT_EAGAIN timeout errors.	5000
columnar-large-projections[=arg]	Sets automatic use of columnar output, instead of row-wise output, for large projections.	TRUE
columnar-large-projections-threshold arg	Set the row-number threshold size for columnar output instead of row-wise output.	1000000
config arg	Path to heavy.conf. Change for testing and debugging.	$HEAVYAI_STORAGE/ heavy.conf
cpu-only	Run in CPU-only mode. Set this flag to force HeavyDB to run in CPU mode, even when GPUs are available. Useful for debugging and on shared-tenancy systems where the current HeavyDB instance does not need to run on GPUs.	FALSE
cpu-buffer- mem-bytes arg	Size (in bytes) of memory reserved for CPU buffers. Change to restrict the amount of CPU/system memory HeavyDB can consume. A default value of 0 indicates that 80% of total CPU memory will be used by the HeavyDB server.	0
cuda-block-size arg	Size of block to use on GPU. GPU performance tuning: Number of threads per block. Default of 0 means use all threads per block.	0
cuda-grid-size arg	Size of grid to use on GPU. GPU performance tuning: Number of blocks per device. Default of 0 means use all available blocks per device.	0
data arg	Directory path to HEAVY.AI catalogs. Change for testing and debugging.	$HEAVYAI_STORAGE
db-query-list arg	Path to file containing HEAVY.AI queries. Use a query list to autoload data to GPU memory on startup to speed performance. See Preloading Data.	N/A
dynamic-watchdog-time-limit [=arg]	Dynamic watchdog time limit, in milliseconds. Change if dynamic watchdog is stopping queries expected to take longer than this limit.	100000
enable-auto-clear-render-mem [=arg]	Enable/disable clear render gpu memory on out-of-memory errors during rendering. If an out-of-gpu-memory exception is thrown while rendering, many users respond by running \clear_gpu via the heavysql command-line interface to refresh/defrag the memory heap. This process can be automated with this flag enabled. At present, only GPU memory in the renderer is cleared automatically.	TRUE[1]
enable-auto-metadata-update [=arg]	Enable automatic metadata updates on UPDATE queries. Automatic metadata updates are turned on by default. Disabling may result in stale metadata and reductions in query performance.	TRUE[1]
enable-columnar-output [=arg]	Allows HEAVY.AI Core to directly materialize intermediate projections and the final ResultSet in Columnar format where appropriate. Columnar output is an internal performance enhancement that projects the results of an intermediate processing step in columnar format. Consider disabling this feature if you see unexpected performance regressions in your queries.	TRUE[1]
enable-data-recycler [=arg]	Set to TRUE to enable the data recycler. Enabling the recycler enables the following: Hashtable recycler, which is the cache storage. Hashing scheme recycler, which preserves a hashtable layout (such as perfect hashing and keyed hashing). Overlaps hashtable tuning parameter recycler. Each overlap hashtable has its own parameters used during hashtable building.	TRUE[0]
enable-debug-timer [=arg]	Enable fine-grained query execution timers for debug. For debugging, logs verbose timing information for query execution (time to load data, time to compile code, and so on).	FALSE[0]
enable-direct-columnarization [=arg(=1)](=0)	Columnarization organizes intermediate results in a multi-step query in the most efficient way for the next step in the process. If you see an unexpected performance regression, you can try setting this value to false, enabling the earlier HEAVY.AI columnarization behavior.	TRUE[1]
enable-dynamic-watchdog [=arg]	Enable dynamic watchdog.	FALSE[0]
--enable-executor-resource-mgr [=arg]	Disable the executor resource manager.	TRUE[1]
enable-filter-push-down [=arg(=1)] (=0)	Enable filter push-down through joins. Evaluates filters in the query expression for selectivity and pushes down highly selective filters into the join according to selectivity parameters. See also What is Predicate Pushdown?	FALSE[0]
enable-foreign-table-scheduled-refresh [=arg]	Enable scheduled refreshes of foreign tables. Enables automated refresh of foreign tables with "REFRESH_TIMING_TYPE" option of "SCHEDULED" based on the specified refresh schedule.	TRUE[1]
enable-geo-ops-on-uncompressed-coords [=arg(=1)] (=0)	Allow geospatial operations ST_Contains and ST_Intersects to process uncompressed coordinates where possible to increase execution speed. Provides control over the selection of ST_Contains and ST_Intersects implementations. By default, for certain combinations of compressed geospatial arguments, such as ST_Contains(POLYGON, POINT), the implementation can process uncompressed coordinate values. This can result in much faster execution but could decrease precision. Disabling this option enables full decompression, which is slower but more precise.	TRUE[1]
enable-logs-system-tables [=arg(=1)] (=0)	Enable use of logs system tables. Also enables the Request Logs and Monitoring system dashboard (Enterprise Edition only).	FALSE[0]
enable-overlaps-hashjoin [=arg(=1)] (=0)	Enable the overlaps hash join framework allowing for range join (for example, spatial overlaps) computation using a hash table.	TRUE[1]
enable-runtime-query-interrupt [=arg(=1)] (=0)	Enable the runtime query interrupt. Enables runtime query interrupt. Setting to TRUE can reduce performance slightly. Use with runtime-query-interrupt-frequency to set the interrupt frequency.	FALSE[0]
enable-runtime-udf	Enable runtime user defined function registration. Enables runtime registration of user defined functions. This functionality is turned off unless you specifically request it, to prevent unintentional inclusion of nonstandard code. This setting is a precursor to more advanced object permissions planned in future releases.	FALSE[0]
enable-string-dict-hash-cache[=arg(=1)] (=0)	When importing a large table with low cardinality, set the flag to TRUE and leave it on to assist with bulk queries. If using String Dictionary Server, set the flag to FALSE if the String Dictionary server uses more memory than the physical system can support.	TRUE[1]
enable-thrift-logs [=arg(=1)] (=0)	Enable writing messages directly from Thrift to stdout/stderr. Change to enable verbose Thrift messages on the console.	FALSE[0]
enable-watchdog [arg]	Enable watchdog.	TRUE[1]
executor-cpu-result-mem-ratio	Set executor resource manager reserved memory for query result sets as a ratio greater than 0, representing the fraction of the system memory not allocatable for the CPU buffer pool. Values of 1.0 are permitted to allow over-subscription when warranted, but too high a value can cause out-of-memory errors. Example: In a system with 256GB of Ram, the default of the cpu-buffer-size is 204.8GB so this ratio will be calculated on 51.2GB, limiting the maximum result set memory for a single query to 41GB
Executor-cpu-result-mem-bytes	Set executor resource manager reserved memory for query result sets in bytes. This overrides the default reservation of 80% the size of the system memory that is not allocated for the CPU buffer pool. Use 0 for auto.	DEFAULT: None (result memory size is controlled via the ratio setting above)
executor-per-query-max-cpu-threads-ratio	Set max fraction of executor resource manager total CPU slots/threads that can be allocated for a single query. Note we allow executor-per-query-max-cpu-threads-ratio to have values > 1 to allow over-subscription of threads when warranted, given we may be overly pessimistic about kernel core occupation for some classes of queries. Care should be taken however with setting this value too high as thrashing and thread starvation can result. Example: on a physical server with 24 logical CPUs or in a VM with 24 vCPU the executor thread will be doubled to 48, so a value of 0.9 will use up 43 threads for a single query. This value can be lowered to lower memory requirements of single queries.	DEFAULT: 0.9
executor-per-query-max-cpu-result-mem-ratio	Set max fraction of executor resource manager total CPU result memory reservation that can be allocated for a single query. Note we allow executor-per-query-max-cpu-result-mem-ratio to have values > 0 to allow over-subscription of memory when warranted, but user should be careful with this as too high a value can cause out-of-memory errors.	Default: 0.8
filter-push-down-low-frac	Higher threshold for selectivity of filters which are pushed down. Filters with selectivity lower than this threshold are considered for a push down.
filter-push-down-passing-row-ubound	Upper bound on the number of rows that should pass the filter if the selectivity is less than the high fraction threshold.
flush-log [arg]	Immediately flush logs to disk. Set to FALSE if this is a performance bottleneck.	TRUE[1]
from-table-reordering [=arg(=1)] (=1)	Enable automatic table reordering in FROM clause. Reorders the sequence of a join to place large tables on the inside of the join clause and smaller tables on the outside. HEAVY.AI also reorders tables between join clauses to prefer hash joins over loop joins. Change this value only in consultation with an HEAVY.AI engineer.	TRUE[1]
gpu-buffer-mem-bytes [=arg]	Size of memory reserved for GPU buffers in bytes per GPU. Change to restrict the amount of GPU memory HeavyDB can consume per GPU. A default value of 0 indicates no limit on GPU memory use (HeavyDB uses all available GPU memory across all active GPUs on the system).	0
gpu-code-cache-max-size-in-bytes [=arg]	Maximum amount of memory in bytes that can be used for the GPU code cache.	134217728 (128MB)
gpu-input-mem-limit arg	Force query to CPU when input data memory usage exceeds this percentage of available GPU memory. OmniSciDB loads data to GPU incrementally until data exceeds GPU memory, at which point the system retries on CPU. Loading data to GPU evicts any resident data already loaded or any query results that are cached. Use this limit to avoid attempting to load datasets to GPU when they obviously will not fit, preserving cached data on GPU and increasing query performance. If watchdog is enabled and allow-cpu-retry is not enabled, the query fails instead of re-running on CPU.	0.9
hashtable-cache-total-bytes [=arg]	The total size of the cache storage for hashtable recycler, in bytes. Increase the cache size to store more hashtables. Must be larger than or equal to the value defined in max-cacheable-hashtable-size-bytes.	4294967296 (4GB)
hll-precision-bits [=arg]	Number of bits used from the hash value used to specify the bucket number. Change to increase or decrease approx_count_distinct() precision. Increased precision decreases performance.	11
http-port arg	HTTP port number. Change to avoid collisions with ports already in use.	6278
idle-session-duration arg	Maximum duration of an idle session, in minutes. Change to increase or decrease duration of an idle session before timeout.	60
inner-join-fragment-skipping [=arg(=1)] (=0)	Enable or disable inner join fragment skipping. Enables skipping fragments for improved performance during inner join operations.	FALSE[0]
license arg	Path to the file containing the license key. Change if your license file is in a different location or has a different name.
log-auto-flush	Flush logging buffer to file after each message. Changing to false can improve performance, but log lines might not appear in the log for a very long time. HEAVY.AI does not recommend changing this setting.	TRUE[1]
log-directory arg	Path to the log directory. Can be either a relative path to the $HEAVYAI_STORAGE/data directory or an absolute path. Use this flag to control the location of your HEAVY.AI log files. If the directory does not exist, HEAVY.AI creates the top level directory. For example, a/b/c/logdir is created only if the directory path a/b/c already exists.	/var/lib/heavyai/ data/heavyai_log
log-file-name	Boilerplate for the name of the HEAVY.AI log files. You can customize the name of your HEAVY.AI log files. {SEVERITY} is the only braced token recognized. It allows you to create separate files for each type of error message greater than or equal to the log-severity configuration option.	heavydb.{SEVERITY}. %Y%m%d-%H%M%S.log
log-max-files	Maximum number of log files to keep. When the number of log files exceeds this number, HEAVY.AI automatically deletes the oldest files.	100
log-min-free-space	Minimum number of bytes left on device before oldest log files are deleted. This is a safety feature to be sure the disk drive of the log directory does not fill up, and guarantees that at least this many bytes are free.	20971520
log-rotation-size	Maximum file size in bytes before new log files are started. Change to increase/decrease size of files. If log files fill quickly, you might want to increase this number so that there are fewer log files.	10485760
log-rotate-daily	Start new log files at midnight. Set to false to write to log files until they are full, rather than restarting each day.	TRUE[1]
log-severity	Log to file severity levels: DEBUG4 DEBUG3 DEBUG2 DEBUG1 INFO WARNING ERROR FATAL All levels after your chosen base severity level are listed. For example, if you set the severity level to WARNING, HEAVY.AI only logs WARNING, ERROR, and FATAL messages.	INFO
log-severity-clog	Log to console severity level: INFO WARNING ERROR FATAL. Output chosen severity messages to STDERR from running process.	WARNING
log-symlink	Symbolic link to the active log. Creates a symbolic link for every severity greater than or equal to the log-severity configuration option.	heavydb. {SEVERITY}.log
log-user-id	Log internal numeric user IDs instead of textual user names.
log-user-origin	Look up the origin of inbound connections by IP address and DNS name and print this information as part of stdlog. Some systems throttle DNS requests or have other network constraints that preclude timely return of user origin information. Set to FALSE to improve performance on those networks or when large numbers of users from different locations make rapid connect/disconnect requests to the server.	TRUE[1]
logs-system-tables-max-files-count [=arg]	Maximum number of log files that can be processed by each logs system table.	100
max-cacheable-hashtable-size-bytes [=arg]	Maximum size of the hashtable that the hashtable recycler can store. Limiting the size can enable more hashtables to be stored. Must be lesser than or equal to the value defined in hashtable-cache-total-bytes.	2147483648 (2GB)
max-session-duration arg	Maximum duration of the active session, in minutes. Change to increase or decrease session duration before timeout.	43200 (30 days)
ndv-group-estimator-multiplier	A value that determines how the result of the Number of Distinct Values (NDV) group estimator is scaled. This value must be between 1.0 and 2.0.	1.5
null-div-by-zero [=arg]	Allows processing to complete when when the dataset would cause a divide by zero error. Set to TRUE if you prefer to return null when dividing by zero, and set to FALSE to throw an exception.	FALSE[0]
num-executors arg	Beta functionality in Release 5.7. Set the number of executors.
num-gpus arg	Number of GPUs to use. In a shared environment, you can assign the number of GPUs to a particular application. The default, -1, uses all available GPUs. Use in conjunction with start-gpu.	-1
num-reader-threads arg	Number of reader threads to use. Drop the number of reader threads to prevent imports from using all available CPU power. Default is to use all threads.	0
overlaps-bucket- threshold arg	The minimum size of a bucket corresponding to a given inner table range for the overlaps hash join.
-p | port int	HeavyDB server port. Change to avoid collisions with other services if 6274 is already in use.	6274
pending-query-interrupt-freq=arg	Frequency with which to check the interrupt status of pending queries, in milliseconds. Values larger than 0 are valid. If you set pending-query-interrupt-freq=100, each session's interrupt status is checked every 100 ms. For example, assume you have three sessions (S1, S2, and S3) in your queue, and assume S1 contains a running query, and S2 and S3 hold pending queries. If you setpending-query-interrupt-freq=1000 both S2 and S3 are interrupted every 1000 ms (1 sec). See running-query-interrupt-freq for information about interrupting running queries. Decreasing the value increases the speed with which pending queries are removed, but also increases resource usage.	1000 (1 sec)
pki-db-client-auth [=arg]	Attempt authentication of users through a PKI certificate. Set to TRUE for the server to attempt PKI authentication.	FALSE[0]
read-only [=arg(=1)]	Enable read-only mode. Prevents changes to the dataset.	FALSE[0]
render-mem-bytes arg	Specifies the size of a per-GPU buffer that render query results are written to; allocated at the first rendering call. Persists while the server is running unless you run \clear_gpu_memory. Increase if rendering a large number of points or symbols and you get the following out-of-memory exception: Not enough OpenGL memory to render the query results. Default is 500 MB.	500000000
render-oom-retry-threshold = arg	A render execution time limit in milliseconds to retry a render request if an out-of-gpu-memory error is thrown. Requires enable-auto-clear-render-mem = true. If enable-auto-clear-render-mem = true, a retry of the render request can be performed after an out-of-gpu-memory exception. A retry only occurs if the first run took less than the threshold set here (in milliseconds). The retry is attempted after the render gpu memory is automatically cleared. If an OOM exception occurs, clearing the memory might get the request to succeed. Providing a reasonable threshold might give more stability to memory-constrained servers w/ rendering enabled. Only a single retry is attempted. A value of 0 disables retries.
rendering [=arg]	Enable or disable backend rendering. Disable rendering when not in use, freeing up memory reserved by render-mem-bytes. To reenable rendering, you must restart HEAVY.AI Server.	TRUE[1]
res-gpu-mem =arg	Reserved memory for GPU. Reserves extra memory for your system (for example, if the GPU is also driving your display, such as on a laptop or single-card desktop). HEAVY.AI uses all the memory on the GPU except for render-mem-bytes + res-gpu-mem. Also useful if other processes, such as a machine-learning pipeline, share the GPU with HEAVY.AI. In advanced rendering scenarios or distributed setups, increase to free up additional memory for the renderer, or for aggregating results for the renderer from multiple leaf nodes. HEAVY.AI recommends always setting res-gpu-mem when using backend rendering.	134217728
running-query-interrupt-freq arg	Controls the frequency of interruption status checking for running queries. Range: 0.0 (less frequently) to 1.0 (more frequently). For example, if you have 10 threads that evaluate a query of a table that has 1000 rows, then each thread advances its thread index up to 10 times. In this case, if you set the flag close to 1.0, you check a session's interrupt status for every increment of the thread index. If we set the flag value as close to 0.0, you only check the session's interrupt status when the index increment is close to 10. The default value of running interrupt checking is close to half of the maximum increment of the thread index. Frequent interrupt status checking reduces latency for the interrupt but also can decrease query performance.
seek-kafka-commit = <N>	Set the offset of the last Kafka message to be committed from a Kafka data stream. Set the offset of the last Kafka message to be committed from a Kafka data stream. This way, Kafka does not resend those messages. After the Kafka server commits messages through the number N, it resends messages starting at message N+1. This is particularly useful when you want to create a replica of the HEAVY.AI server from an existing data directory.	N/A
ssl-cert path	Path to the server's public PKI certificate (.crt file). Define the path the the .crt file. Used to establish an encrypted binary connection.
ssl-keystore path	Path to the server keystore. Used for an encrypted binary connection. The path to Java trust store containing the server's public PKI key. Used by HeavyDB to connect to the encrypted Calcite server port.
ssl-keystore-password password	The password for the SSL keystore. Used to create a binary encrypted connection to the Calcite server.
ssl-private-key path	Path to the server's private PKI key. Define the path to the HEAVY.AI server PKI key. Used to establish an encrypted binary connection.
ssl-trust-ca path	Enable use of CA-signed certificates presented by Calcite. Defines the file that contains trusted CA certificates. This information enables the server to validate the TCP/IP Thrift connections it makes as a client to the Calcite server. The certificate presented by the Calcite server is the same as the certificate used to identify the database server to its clients.
ssl-trust-ca-server path	Path to the file containing trusted CA certificates; for PKI authentication. Used to validate certificates submitted by clients. If the certificate provided by the client (in the password field of the connect command) was not signed by one of the certificates in the trusted file, then the connection fails. PKI authentication works only if the server is configured to encrypt connections via TLS. The common name extracted from the client certificate is used as the name of the user to connect. If this name does not already exist, the connection fails. If LDAP or SAML are also enabled, the servers fall back to these authentication methods if PKI authentication fails. Currently works only with JDBC clients. To allow connection from other clients, set allow-local-auth-fallback or add LDAP/SAML authentication.
ssl-trust-password password	The password for the SSL trust store. Password to the SSL trust store containing the server's public PKI key. Used to establish an encrypted binary connection.
ssl-trust-store path	The path to Java trustStore containing the server's public PKI key. Used by the Calcite server to connect to the encrypted OmniSci server port, to establish an encrypted binary connection.
start-gpu arg	First GPU to use. Used in shared environments in which the first assigned GPU is not GPU 0. Use in conjunction with num-gpus.	FALSE[0]
trivial-loop-join-threshold [=arg]	The maximum number of rows in the inner table of a loop join considered to be trivially small.	1000
use-cpu-mem-pool-for-output-buffers	Use the CPU memory buffer pool (whose capacity is determined by the cpu-buffer-mem-bytes configuration parameter) for output buffer allocations. When this configuration parameter is set to false, output (e.g. result set) buffer allocations will use heap memory outside the cpu-buffer-mem-bytes based memory buffer pool.	TRUE[1]
use-hashtable-cache	Set to TRUE to enable the hashtable recycler. Supports complex scenarios, such as hashtable recycling for queries that have subqueries.	TRUE[1]
vacuum-min-selectivity [=arg]	Specify the percentage (with a value of 0 implying 0% and a value of 1 implying 100%) of deleted rows in a fragment at which to perform automatic vacuuming. Automatic vacuuming occurs when deletes or updates on variable-length columns result in a percentage of deleted rows in a fragment exceeding the specified threshold. The default threshold is 10% of deleted rows in a fragment. When changing this value, consider the most common types of queries run on the system. In general, if you have infrequent updates and deletes, set vacuum-min-selectivity to a low value. Set it higher if you have frequent updates and deletes, because vacuuming adds overhead to affected UPDATE and DELETE queries.
watchdog-none-encoded-string-translation-limit [=arg]	The number of strings that can be casted using the ENCODED_TEXT string operator.	1,000,000
window-function-frame-aggregation-tree-fanout [=arg]	Tree fan out of the aggregation tree is used to compute aggregation over the window frame.	8

Additional Enterprise Edition Parameters

Following are additional parameters for runtime settings for the Enterprise Edition of HeavyDB. The parameter syntax provides both the implied value and the default value as appropriate. Optional arguments are in square brackets, while implied and default values are in parentheses.

Flag	Description	Default Value
cluster arg	Path to data leaves list JSON file. Indicates that the HEAVY.AI server instance is an aggregator node, and where to find the rest of its cluster. Change for testing and debugging.	$HEAVYAI_BASE
compression-limit-bytes [=arg(=536870912)] (=536870912)	Compress result sets that are transferred between leaves. Minimum length of payload above which data is compressed.	536870912
compressor arg (=lz4hc)	Compressor algorithm to be used by the server to compress data being transferred between server. See Data Compression for compression algorithm options.	lz4hc
ldap-dn arg	LDAP Distinguished Name.
ldap-role-query-regex arg	RegEx to use to extract role from role query result.
ldap-role-query-url arg	LDAP query role URL.
ldap-superuser-role arg	The role name to identify a superuser.
ldap-uri arg	LDAP server URI.
leaf-conn-timeout [=arg]	Leaf connect timeout, in milliseconds. Increase or decrease to fail Thrift connections between HeavyDB instances more or less quickly if a connection cannot be established.	20000
leaf-recv-timeout [=arg]	Leaf receive timeout, in milliseconds. Increase or decrease to fail Thrift connections between HeavyDB instances more or less quickly if data is not received in the time allotted.	300000
leaf-send-timeout [=arg]	Leaf send timeout, in milliseconds. Increase or decrease to fail Thrift connections between HeavyDB instances more or less quickly if data is not sent in the time allotted.	300000
saml-metadata-file arg	Path to identity provider metadata file. Required for running SAML. An identity provider (like Okta) supplies a metadata file. From this file, HEAVY.AI uses: Public key of the identity provider to verify that the SAML response comes from it and not from somewhere else. URL of the SSO login page used to obtain a SAML token.
saml-sp-target-url arg	URL of the service provider for which SAML assertions should be generated. Required for running SAML. Used to verify that a SAML token was issued for HEAVY.AI and not for some other service.
saml-sync-roles arg (=0)	Enable mapping of SAML groups to HEAVY.AI roles. The SAML Identity provider (for example, Okta) automatically creates users at login and assigns them roles they already have as groups in SAML.	saml-sync-roles [=0]
string-servers arg	Path to string servers list JSON file. Indicates that HeavyDB is running in distributed mode and is required to designate a leaf server when running in distributed mode.