Configuration

This page describes methods for configuring QuestDB server settings.

Configuration can be set either:

• In the server.conf configuration file available in the root directory
• Using environment variables

When a key is absent from both the config file and the environment variables, the default value is used.

note

For Windows users

When entering path values, use either \\ or / instead of the native path separator char \.

• 👍 C:\\path\\to\\file\\path
• 👍 C:/path/to/file
• 👎 C:\path\to\file

The single backslash is interpreted as an escape sequence start within Java properties.

Environment variables

All settings in the configuration file can be set or overridden using environment variables. If a key is set in both the server.conf file and via an environment variable, the environment variable will take precedence and the value in the server configuration file will be ignored.

To make these configuration settings available to QuestDB via environment variables, they must be in the following format:

QDB_<KEY_OF_THE_PROPERTY>

Where <KEY_OF_THE_PROPERTY> is equal to the configuration key name. To properly format a server.conf key as an environment variable it must have:

1. QDB_ prefix
2. uppercase characters
3. all . period characters replaced with _ underscore

For example, the server configuration key for shared workers must be passed as described below:

server.conf key	env var
shared.worker.count	QDB_SHARED_WORKER_COUNT

note

QuestDB applies these configuration changes on startup and a running instance must be restarted in order for configuration changes to take effect

Examples

The following configuration property customizes the number of worker threads shared across the application:

conf/server.conf

shared.worker.count=5

Customizing the worker count via environment variable

export QDB_SHARED_WORKER_COUNT=5

Keys and default values

This section lists the configuration keys available to QuestDB by topic or subsystem. Parameters for specifying buffer and memory page sizes are provided in the format n<unit>, where <unit> can be one of the following:

• m for MB
• k for kB

For example:

Setting maximum send buffer size to 2MB per TCP socket

http.net.connection.sndbuf=2m

Shared worker

Shared worker threads service SQL execution subsystems and (in the default configuration) every other subsystem.

Property	Default	Description
shared.worker.count		Number of worker threads shared across the application. Increasing this number will increase parallelism in the application at the expense of CPU resources.
shared.worker.affinity		Comma-delimited list of CPU ids, one per thread specified in shared.worker.count. By default, threads have no CPU affinity.
shared.worker.haltOnError	false	Flag that indicates if the worker thread must stop when an unexpected error occurs.

HTTP server

This section describes configuration settings for the Web Console and the REST API available by default on port 9000. For details on the use of this component, refer to the web console documentation page.

Property	Default	Description
http.enabled	true	Enable or disable HTTP server.
http.bind.to	0.0.0.0:9000	IP address and port of HTTP server. A value of 0 means that the HTTP server will bind to all network interfaces. You can specify IP address of any individual network interface on your system.
http.user	N/A	Username for HTTP Basic Authentication in QuestDB Open Source. QuestDB Enterprise Edition supports more advanced authentication mechanisms: RBAC
http.password	N/A	Password for HTTP Basic Authentication in QuestDB Open Source. QuestDB Enterprise Edition supports more advanced authentication mechanisms: RBAC
http.net.connection.limit	64	The maximum number permitted for simultaneous TCP connection to the HTTP server. The rationale of the value is to control server memory consumption.
http.net.connection.timeout	300000	TCP connection idle timeout in milliseconds. Connection is closed by HTTP server when this timeout lapses.
http.net.connection.sndbuf	2M	Maximum send buffer size on each TCP socket. If this value is -1, the socket send buffer size remains unchanged from the OS defaults.
http.net.connection.rcvbuf	2M	Maximum receive buffer size on each TCP socket. If this value is -1, the socket receive buffer size remains unchanged from the OS defaults.
http.net.connection.hint	false	Windows specific flag to overcome OS limitations on TCP backlog size
http.net.connection.queue.timeout	5000	Amount of time in milliseconds a connection can wait in the listen backlog queue before it is refused. Connections will be aggressively removed from the backlog until the active connection limit is breached.
http.net.bind.to	0.0.0.0:9000	IP address and port of HTTP server.
http.connection.pool.initial.capacity	4	Initial size of pool of reusable objects that hold connection state. The pool should be configured to maximum realistic load so that it does not resize at runtime.
http.connection.string.pool.capacity	128	Initial size of the string pool shared by the HTTP header and multipart content parsers.
http.multipart.header.buffer.size	512	Buffer size in bytes used by the HTTP multipart content parser.
http.multipart.idle.spin.count	10000	How long the code accumulates incoming data chunks for column and delimiter analysis.
http.receive.buffer.size	1M	Size of receive buffer.
http.request.header.buffer.size	64K	Size of internal buffer allocated for HTTP request headers. The value is rounded up to the nearest power of 2. When HTTP requests contain headers that exceed the buffer size server will disconnect the client with HTTP error in server log.
http.response.header.buffer.size	32K	Size of the internal response buffer. The value will be rounded up to the nearest power of 2. The buffer size should be large enough to accommodate max size of server response headers.
http.worker.count	0	Number of threads in private worker pool. When 0, HTTP server will be using shared worker pool of the server. Values above 0 switch on private pool.
http.worker.affinity		Comma separated list of CPU core indexes. The number of items in this list must be equal to the worker count.
http.worker.haltOnError	false	Changing the default value is strongly discouraged. Flag that indicates if the worker thread must stop when an unexpected error occurs.
http.send.buffer.size	2M	Size of the internal send buffer. Larger buffer sizes result in fewer I/O interruptions the server is making at the expense of memory usage per connection. There is a limit of send buffer size after which increasing it stops being useful in terms of performance. 2MB seems to be optimal value.
http.static.index.file.name	index.html	Name of index file for the Web Console.
http.frozen.clock	false	Sets the clock to always return zero. This configuration parameter is used for internal testing.
http.allow.deflate.before.send	false	Flag that indicates if Gzip compression of outgoing data is allowed.
http.keep-alive.timeout	5	Used together with http.keep-alive.max to set the value of HTTP Keep-Alive response header. This instructs browser to keep TCP connection open. Has to be 0 when http.version is set to HTTP/1.0.
http.keep-alive.max	10000	See http.keep-alive.timeout. Has to be 0 when http.version is set to HTTP/1.0.
http.static.public.directory	public	The name of directory for public web site.
http.text.date.adapter.pool.capacity	16	Size of date adapter pool. This should be set to the anticipated maximum number of DATE fields a text input can have. The pool is assigned to connection state and is reused alongside of connection state object.
http.text.json.cache.limit	16384	JSON parser cache limit. Cache is used to compose JSON elements that have been broken up by TCP protocol. This value limits the maximum length of individual tag or tag value.
http.text.json.cache.size	8192	Initial size of JSON parser cache. The value must not exceed http.text.json.cache.limit and should be set to avoid cache resizes at runtime.
http.text.max.required.delimiter.stddev	0.1222d	The maximum standard deviation value for the algorithm that calculates text file delimiter. Usually when text parser cannot recognise the delimiter it will log the calculated and maximum standard deviation for the delimiter candidate.
http.text.max.required.line.length.stddev	0.8	Maximum standard deviation value for the algorithm that classifies input as text or binary. For the values above configured stddev input will be considered binary.
http.text.metadata.string.pool.capacity	128	The initial size of pool for objects that wrap individual elements of metadata JSON, such as column names, date pattern strings and locale values.
http.text.roll.buffer.limit	4M	The limit of text roll buffer. See http.text.roll.buffer.size for description.
http.text.roll.buffer.size	1024	Roll buffer is a structure in the text parser that holds a copy of a line that has been broken up by TCP. The size should be set to the maximum length of text line in text input.
http.text.analysis.max.lines	1000	Number of lines to read on CSV import for heuristics which determine column names & types. Lower line numbers may detect CSV schemas quicker, but possibly with less accuracy. 1000 lines is the maximum for this value.
http.text.lexer.string.pool.capacity	64	The initial capacity of string fool, which wraps STRING column types in text input. The value should correspond to the maximum anticipated number of STRING columns in text input.
http.text.timestamp.adapter.pool.capacity	64	Size of timestamp adapter pool. This should be set to the anticipated maximum number of TIMESTAMP fields a text input can have. The pool is assigned to connection state and is reused alongside of connection state object.
http.text.utf8.sink.size	4096	Initial size of UTF-8 adapter sink. The value should correspond the maximum individual field value length in text input.
http.json.query.connection.check.frequency	1000000	Changing the default value is strongly discouraged. The value to throttle check if client socket has been disconnected.
http.json.query.float.scale	4	The scale value of string representation of FLOAT values.
http.json.query.double.scale	12	The scale value of string representation of DOUBLE values.
http.query.cache.enabled	true	Enable or disable the query cache. Cache capacity is number_of_blocks * number_of_rows.
http.query.cache.block.count	4	Number of blocks for the query cache.
http.query.cache.row.count	16	Number of rows for the query cache.
http.security.readonly	false	Forces HTTP read only mode when true, disabling commands which modify the data or data structure, e.g. INSERT, UPDATE, or CREATE TABLE.
http.security.max.response.rows	2^63-1	Limit the number of response rows over HTTP.
http.security.interrupt.on.closed.connection	true	Switch to enable termination of SQL processing if the HTTP connection is closed. The mechanism affects performance so the connection is only checked after circuit.breaker.throttle calls are made to the check method. The mechanism also reads from the input stream and discards it since some HTTP clients send this as a keep alive in between requests, circuit.breaker.buffer.size denotes the size of the buffer for this.
http.pessimistic.health.check.enabled	false	When enabled, the health check returns HTTP 500 for any unhandled errors since the server started.
circuit.breaker.throttle	2000000	Number of internal iterations such as loops over data before checking if the HTTP connection is still open
circuit.breaker.buffer.size	32	Size of buffer to read from HTTP connection. If this buffer returns zero and the HTTP client is no longer sending data, SQL processing will be terminated.
http.server.keep.alive	true	If set to false, the server will disconnect the client after completion of each request.
http.version	HTTP/1.1	Protocol version, other supported value is HTTP/1.0.

Cairo engine

This section describes configuration settings for the Cairo SQL engine in QuestDB.

Property	Default	Description
query.timeout.sec	60	A global timeout (in seconds) for long-running queries. Timeout for each query can override the default by setting HTTP header Statement-Timeout or Postgres options.
cairo.max.uncommitted.rows	500000	Maximum number of uncommitted rows per table, when the number of pending rows reaches this parameter on a table, a commit will be issued.
cairo.o3.max.lag	10 minutes	The maximum size of in-memory buffer in milliseconds. The buffer is allocated dynamically through analyzing the shape of the incoming data, and o3MaxLag is the upper limit.
cairo.o3.min.lag	1 second	The minimum size of in-memory buffer in milliseconds. The buffer is allocated dynamically through analyzing the shape of the incoming data, and o3MinLag is the lower limit.
cairo.sql.backup.root	null	Output root directory for backups.
cairo.sql.backup.dir.datetime.format	null	Date format for backup directory.
cairo.sql.backup.dir.tmp.name	tmp	Name of tmp directory used during backup.
cairo.sql.backup.mkdir.mode	509	Permission used when creating backup directories.
cairo.snapshot.instance.id	empty string	Instance id to be included into disk snapshots.
cairo.snapshot.recovery.enabled	true	When false, disables snapshot recovery on database start.
cairo.root	db	Directory for storing db tables and metadata. This directory is inside the server root directory provided at startup.
cairo.commit.mode	nosync	How changes to table are flushed to disk upon commit. Choices: nosync, async (flush call schedules update, returns immediately), sync (waits for flush on the appended column files to complete).
cairo.rnd.memory.max.pages	128	Sets the max number of pages for memory used by rnd_ functions. Supports rnd_str() and rnd_symbol().
cairo.rnd.memory.page.size	8K	Sets the memory page size used by rnd_ functions. Supports rnd_str() and rnd_symbol().
cairo.create.as.select.retry.count	5	Number of types table creation or insertion will be attempted.
cairo.default.map.type	fast	Type of map used. Options: fast (speed at the expense of storage), compact.
cairo.default.symbol.cache.flag	true	When true, symbol values will be cached on Java heap instead of being looked up in the database files.
cairo.default.symbol.capacity	256	Specifies approximate capacity for SYMBOL columns. It should be equal to number of unique symbol values stored in the table and getting this value badly wrong will cause performance degradation. Must be power of 2.
cairo.file.operation.retry.count	30	Number of attempts to open files.
cairo.idle.check.interval	300000	Frequency of writer maintenance job in milliseconds.
cairo.inactive.reader.ttl	120000	TTL (Time-To-Live) to close inactive readers in milliseconds.
cairo.wal.inactive.writer.ttl	120000	TTL (Time-To-Live) to close inactive WAL writers in milliseconds.
cairo.inactive.writer.ttl	600000	TTL (Time-To-Live) to close inactive writers in milliseconds.
cairo.index.value.block.size	256	Approximation of number of rows for a single index key, must be power of 2.
cairo.max.swap.file.count	30	Number of attempts to open swap files.
cairo.mkdir.mode	509	File permission mode for new directories.
cairo.parallel.index.threshold	100000	Minimum number of rows before allowing use of parallel indexation.
cairo.reader.pool.max.segments	10	Number of segments in the table reader pool. Each segment holds up to 32 readers.
cairo.wal.writer.pool.max.segments	10	Number of segments in the WAL writer pool. Each segment holds up to 32 writers.
cairo.spin.lock.timeout	1000	Timeout when attempting to get BitmapIndexReaders in millisecond.
cairo.character.store.capacity	1024	Size of the CharacterStore.
cairo.character.store.sequence.pool.capacity	64	Size of the CharacterSequence pool.
cairo.column.pool.capacity	4096	Size of the Column pool in the SqlCompiler.
cairo.compact.map.load.factor	0.7	Load factor for CompactMaps.
cairo.expression.pool.capacity	8192	Size of the ExpressionNode pool in SqlCompiler.
cairo.fast.map.load.factor	0.5	Load factor for all FastMaps.
cairo.sql.join.context.pool.capacity	64	Size of the JoinContext pool in SqlCompiler.
cairo.lexer.pool.capacity	2048	Size of FloatingSequence pool in GenericLexer.
cairo.sql.map.key.capacity	2M	Key capacity in FastMap and CompactMap.
cairo.sql.map.max.resizes	2^31	Number of map resizes in FastMap and CompactMap before a resource limit exception is thrown, each resize doubles the previous size.
cairo.sql.map.page.size	4m	Memory page size for FastMap and CompactMap.
cairo.sql.map.max.pages	2^31	Memory max pages for CompactMap.
cairo.model.pool.capacity	1024	Size of the QueryModel pool in the SqlCompiler.
cairo.sql.sort.key.page.size	4M	Memory page size for storing keys in LongTreeChain.
cairo.sql.sort.key.max.pages	2^31	Max number of pages for storing keys in LongTreeChain before a resource limit exception is thrown.
cairo.sql.sort.light.value.page.size	1048576	Memory page size for storing values in LongTreeChain.
cairo.sql.sort.light.value.max.pages	2^31	Max pages for storing values in LongTreeChain.
cairo.sql.hash.join.value.page.size	16777216	Memory page size of the slave chain in full hash joins.
cairo.sql.hash.join.value.max.pages	2^31	Max pages of the slave chain in full hash joins.
cairo.sql.latest.by.row.count	1000	Number of rows for LATEST BY.
cairo.sql.hash.join.light.value.page.size	1048576	Memory page size of the slave chain in light hash joins.
cairo.sql.hash.join.light.value.max.pages	2^31	Max pages of the slave chain in light hash joins.
cairo.sql.sort.value.page.size	16777216	Memory page size of file storing values in SortedRecordCursorFactory.
cairo.sql.sort.value.max.pages	2^31	Max pages of file storing values in SortedRecordCursorFactory.
cairo.work.steal.timeout.nanos	10000	Latch await timeout in nanos for stealing indexing work from other threads.
cairo.parallel.indexing.enabled	true	Allows parallel indexation. Works in conjunction with cairo.parallel.index.threshold.
cairo.sql.join.metadata.page.size	16384	Memory page size for JoinMetadata file.
cairo.sql.join.metadata.max.resizes	2^31	Number of map resizes in JoinMetadata before a resource limit exception is thrown, each resize doubles the previous size.
cairo.sql.analytic.column.pool.capacity	64	Size of AnalyticColumn pool in SqlParser.
cairo.sql.create.table.model.pool.capacity	16	Size of CreateTableModel pool in SqlParser.
cairo.sql.create.table.model.batch.size	1000000	Batch size for non-atomic CREATE AS SELECT statements.
cairo.sql.column.cast.model.pool.capacity	16	Size of CreateTableModel pool in SqlParser.
cairo.sql.rename.table.model.pool.capacity	16	Size of RenameTableModel pool in SqlParser.
cairo.sql.with.clause.model.pool.capacity	128	Size of WithClauseModel pool in SqlParser.
cairo.sql.insert.model.pool.capacity	64	Size of InsertModel pool in SqlParser.
cairo.sql.insert.model.batch.size	1000000	Batch size for non-atomic INSERT INTO SELECT statements.
cairo.sql.copy.model.pool.capacity	32	Size of CopyModel pool in SqlParser.
cairo.sql.copy.buffer.size	2M	Size of buffer used when copying tables.
cairo.sql.double.cast.scale	12	Maximum number of decimal places that types cast as doubles have.
cairo.sql.float.cast.scale	4	Maximum number of decimal places that types cast as floats have.
cairo.sql.copy.formats.file	/text_loader.json	Name of file with user's set of date and timestamp formats.
cairo.sql.jit.mode	on	JIT compilation for SQL queries. May be disabled by setting this value to off.
cairo.sql.jit.debug.enabled	false	Sets debug flag for JIT compilation. When enabled, assembly will be printed into stdout.
cairo.sql.jit.bind.vars.memory.page.size	4K	Sets the memory page size for storing bind variable values for JIT compiled filter.
cairo.sql.jit.bind.vars.memory.max.pages	8	Sets the max memory pages for storing bind variable values for JIT compiled filter.
cairo.sql.jit.rows.threshold	1M	Sets minimum number of rows to shrink filtered rows memory after query execution.
cairo.sql.jit.page.address.cache.threshold	1M	Sets minimum cache size to shrink page address cache after query execution.
cairo.sql.jit.ir.memory.page.size	8K	Sets the memory page size for storing IR for JIT compilation.
cairo.sql.jit.ir.max.pages	8	Sets max memory pages for storing IR for JIT compilation.
cairo.sql.page.frame.min.rows	1000	Sets the minimum number of rows in page frames used in SQL queries.
cairo.sql.page.frame.max.rows	1000000	Sets the maximum number of rows in page frames used in SQL. queries
cairo.sql.sampleby.page.size	0	SampleBy index query page size. Max values returned in single scan. 0 is default, and it means to use symbol block capacity.
cairo.sql.sampleby.default.alignment.calendar	0	SampleBy default alignment behaviour. true corresponds to ALIGN TO CALENDAR, false corresponds to ALIGN TO FIRST OBSERVATION.
cairo.date.locale	en	The locale to handle date types.
cairo.timestamp.locale	en	The locale to handle timestamp types.
cairo.o3.column.memory.size	256k	Memory page size per column for O3 operations. Please be aware O3 will use 2x of the set value per column (therefore a default of 2x256kb).
cairo.writer.data.append.page.size	16M	mmap sliding page size that table writer uses to append data for each column.
cairo.writer.data.index.key.append.page.size	512K	mmap page size for appending index key data; key data is number of distinct symbol values times 4 bytes.
cairo.writer.data.index.value.append.page.size	16M	mmap page size for appending value data.
cairo.writer.misc.append.page.size	4K	mmap page size for mapping small files, default value is OS page size (4k Linux, 64K windows, 16k OSX M1). Overriding this rounds to the nearest (greater) multiple of the OS page size.
cairo.writer.command.queue.capacity	32	Maximum writer ALTER TABLE and replication command capacity. Shared between all the tables.
cairo.writer.tick.rows.count	1024	Row count to check writer command queue after on busy writing, e.g. tick after X rows written.
cairo.writer.alter.busy.wait.timeout	500	Maximum wait timeout in milliseconds for ALTER TABLE SQL statement run via REST and PostgreSQL Wire Protocol interfaces when statement execution is ASYNCHRONOUS.
cairo.sql.column.purge.queue.capacity	128	Purge column version job queue. Increase the size if column version not automatically cleanup after execution of UPDATE SQL statement. Reduce to decrease initial memory footprint.
cairo.sql.column.purge.task.pool.capacity	256	Column version task object pool capacity. Increase to reduce GC, reduce to decrease memory footprint.
cairo.sql.column.purge.retry.delay	10000	Initial delay (μs) before re-trying purge of stale column files.
cairo.sql.column.purge.retry.delay.multiplier	10.0	Multiplier used to increases retry delay with each iteration.
cairo.sql.column.purge.retry.delay.limit	60000000	Delay limit (μs), upon reaching which, the re-try delay remains constant.
cairo.sql.column.purge.retry.limit.days	31	Number of days purge system will continue to re-try deleting stale column files before giving up.
cairo.volumes	-	A comma separated list of alias -> root-path pairs defining allowed volumes to be used in CREATE TABLE IN VOLUME statements.
cairo.system.table.prefix	sys.	Prefix of the tables used for QuestDB internal data storage. These tables are hidden from QuestDB web console.
cairo.wal.enabled.default	true	Setting defining whether WAL table is the default when using CREATE TABLE.
cairo.o3.partition.split.min.size	50MB	The estimated partition size on disk. This setting is one of the conditions to trigger auto-partitioning.
cairo.o3.last.partition.max.splits	20	The number of partition pieces allowed before the last partition piece is merged back to the physical partition.
cairo.o3.partition.purge.list.initial.capacity	1	Number of partition expected on average. Initial value for purge allocation job, extended in runtime automatically.
cairo.sql.parallel.groupby.enabled	true	Enables parallel GROUP BY execution; requires at least 4 shared worker threads.
cairo.sql.parallel.groupby.merge.shard.queue.capacity	<auto>	Merge queue capacity for parallel GROUP BY; used for parallel tasks that merge shard hash tables.
cairo.sql.parallel.groupby.sharding.threshold	100000	Threshold for parallel GROUP BY to shard the hash table holding the aggregates.
cairo.sql.groupby.allocator.default.chunk.size	128k	Default size for memory buffers in GROUP BY function native memory allocator.
cairo.sql.groupby.allocator.max.chunk.size	4gb	Maximum allowed native memory allocation for GROUP BY functions.
cairo.sql.unordered.map.max.entry.size	24	Threshold in bytes for switching from single memory buffer hash table (unordered) to a hash table with separate heap for entries (ordered).
cairo.sql.window.max.recursion	128	Prevents stack overflow errors when evaluating complex nested SQLs. The value is an approximate number of nested SELECT clauses.
cairo.sql.query.registry.pool.size	<auto>	Pre-sizes the internal data structure that stores active query executions. The value is chosen automatically based on the number of threads in the shared worker pool.
cairo.sql.analytic.initial.range.buffer.size	32	Window function buffer size in record counts. Pre-sizes buffer for every windows function execution to contain window records.
cairo.system.writer.data.append.page.size	256k	mmap sliding page size that TableWriter uses to append data for each column specifically for System tables.

WAL table configurations

The following WAL tables settings on parallel threads are configurable for applying WAL data to the table storage:

Property	Default	Description
wal.apply.worker.count	equal to the CPU core count	Number of dedicated worker threads assigned to handle WAL table data.
wal.apply.worker.affinity	equal to the CPU core count	Comma separated list of CPU core indexes.
wal.apply.worker.haltOnError	false	Flag that indicates if the worker thread must stop when an unexpected error occurs.
cairo.wal.purge.interval	30000	Period in ms of how often WAL-applied files are cleaned up from the disk
cairo.wal.segment.rollover.row.count	200000	Row count of how many rows are written to the same WAL segment before starting a new segment. Triggers in conjunction with cairo.wal.segment.rollover.size (whichever is first).
cairo.wal.commit.squash.row.limit	500000	Maximum row count that can be squashed together from multiple transactions before applying to the table. A very low value can delay data visibility.
cairo.wal.squash.uncommitted.rows.multiplier	20.0	Multiplier to cairo.max.uncommitted.rows to calculate the limit of rows that can be kept invisible when writing to WAL table under heavy load, when multiple transactions are to be applied. It is used to reduce the number Out-Of-Order (O3) commits when O3 commits are unavoidable by squashing multiple commits together. Setting it very low can increase O3 commit frequency and decrease the throughput. Setting it too high may cause excessive memory usage and increase the latency.
cairo.wal.max.lag.txn.count	20	Maximum number of transactions that can be kept invisible when writing to WAL table. Once the number is reached, full commit occurs. If not set, defaults to the rounded value of cairo.wal.squash.uncommitted.rows.multiplier.

CSV import

This section describes configuration settings for using COPY to import large CSV files.

Settings for COPY:

Property	Default	Description
cairo.sql.copy.root	import	Input root directory for CSV imports via COPY SQL and for Parquet file reading. This path must not overlap with other directory (e.g. db, conf) of running instance, otherwise import may delete or overwrite existing files. Relative paths are resolved against the server root directory.
cairo.sql.copy.work.root	null	Temporary import file directory. Defaults to root_directory/tmp if not set explicitly.
cairo.iouring.enabled	true	Enable or disable io_uring implementation. Applicable to newer Linux kernels only. Can be used to switch io_uring interface usage off if there's a kernel bug affecting it.
cairo.sql.copy.buffer.size	2 MiB	Size of read buffers used in import.
cairo.sql.copy.log.retention.days	3	Number of days to keep import messages in sys.text_import_log.
cairo.sql.copy.max.index.chunk.size	100M	Maximum size of index chunk file used to limit total memory requirements of import. Indexing phase should use roughly thread_count * cairo.sql.copy.max.index.chunk.size of memory.
cairo.sql.copy.queue.capacity	32	Size of copy task queue. Should be increased if there's more than 32 import workers.

CSV import configuration for Docker

For QuestDB instances using Docker:

• cairo.sql.copy.root must be defined using one of the following settings:
  • The environment variable QDB_CAIRO_SQL_COPY_ROOT.
  • The cairo.sql.copy.root in server.conf.
• The path for the source CSV file is mounted.
• The source CSV file path and the path defined by QDB_CAIRO_SQL_COPY_ROOT are identical.
• It is optional to define QDB_CAIRO_SQL_COPY_WORK_ROOT.

The following is an example command to start a QuestDB instance on Docker, in order to import a CSV file:

docker run -p 9000:9000 \
-v "/tmp/questdb:/var/lib/questdb" \
-v "/tmp/questdb/my_input_root:/var/lib/questdb/questdb_import" \
-e QDB_CAIRO_SQL_COPY_ROOT=/var/lib/questdb/questdb_import \
questdb/questdb

Where:

• -v "/tmp/questdb/my_input_root:/var/lib/questdb/questdb_import": Defining a source CSV file location to be /tmp/questdb/my_input_root on local machine and mounting it to /var/lib/questdb/questdb_import in the container.
• -e QDB_CAIRO_SQL_COPY_ROOT=/var/lib/questdb/questdb_import: Defining the copy root directory to be /var/lib/questdb/questdb_import.

It is important that the two path are identical (/var/lib/questdb/questdb_import in the example).

Parallel SQL execution

This section describes settings that can affect parallelism level of SQL execution and therefore performance.

Property	Default	Description
cairo.sql.parallel.filter.enabled	true	Enable or disable parallel SQL filter execution. JIT compilation takes place only when this setting is enabled.
cairo.sql.parallel.filter.pretouch.enabled	true	Enable column pre-touch as part of the parallel SQL filter execution, to improve query performance for large tables.
cairo.page.frame.shard.count	4	Number of shards for both dispatch and reduce queues. Shards reduce queue contention between SQL statements that are executed concurrently.
cairo.page.frame.reduce.queue.capacity	64	Reduce queue is used for data processing and should be large enough to supply tasks for worker threads (shared worked pool).
cairo.page.frame.rowid.list.capacity	256	Row ID list initial capacity for each slot of the reduce queue. Larger values reduce memory allocation rate, but increase minimal RSS size.
cairo.page.frame.column.list.capacity	16	Column list capacity for each slot of the reduce queue. Used by JIT-compiled filter functions. Larger values reduce memory allocation rate, but increase minimal RSS size.

Postgres wire protocol

This section describes configuration settings for client connections using PostgresSQL wire protocol.

Property	Default	Description
pg.enabled	true	Configuration for enabling or disabling the Postres interface.
pg.net.bind.to	0.0.0.0:8812	IP address and port of Postgres wire protocol server. 0 means that the server will bind to all network interfaces. You can specify IP address of any individual network interface on your system.
pg.net.connection.limit	64	The maximum number permitted for simultaneous Postgres connections to the server. This value is intended to control server memory consumption.
pg.net.connection.timeout	300000	Connection idle timeout in milliseconds. Connections are closed by the server when this timeout lapses.
pg.net.connection.rcvbuf	-1	Maximum send buffer size on each TCP socket. If value is -1 socket send buffer remains unchanged from OS default.
pg.net.connection.sndbuf	-1	Maximum receive buffer size on each TCP socket. If value is -1, the socket receive buffer remains unchanged from OS default.
pg.net.connection.hint	false	Windows specific flag to overcome OS limitations on TCP backlog size
pg.net.connection.queue.timeout	300000	Amount of time in milliseconds a connection can wait in the listen backlog queue before it is refused. Connections will be aggressively removed from the backlog until the active connection limit is breached.
pg.security.readonly	false	Forces PostgreSQL Wire Protocol read only mode when true, disabling commands which modify the data or data structure, e.g. INSERT, UPDATE, or CREATE TABLE.
pg.character.store.capacity	4096	Size of the CharacterStore.
pg.character.store.pool.capacity	64	Size of the CharacterStore pool capacity.
pg.connection.pool.capacity	64	The maximum amount of pooled connections this interface may have.
pg.password	quest	Postgres database password.
pg.user	admin	Postgres database username.
pg.readonly.user.enabled	false	Enable or disable Postgres database read-only user account. When enabled, this additional user can be used to open read-only connections to the database.
pg.readonly.password	quest	Postgres database read-only user password.
pg.readonly.user	user	Postgres database read-only user username.
pg.select.cache.enabled	true	Enable or disable the SELECT query cache. Cache capacity is number_of_blocks * number_of_rows.
pg.select.cache.block.count	16	Number of blocks to cache SELECT query execution plan against text to speed up execution.
pg.select.cache.row.count	16	Number of rows to cache for SELECT query execution plan against text to speed up execution.
pg.insert.cache.enabled	true	Enable or disable the INSERT query cache. Cache capacity is number_of_blocks * number_of_rows.
pg.insert.cache.block.count	8	Number of blocks to cache INSERT query execution plan against text to speed up execution.
pg.insert.cache.row.count	8	Number of rows to cache for INSERT query execution plan against text to speed up execution.
pg.update.cache.enabled	true	Enable or disable the UPDATE query cache. Cache capacity is number_of_blocks * number_of_rows.
pg.update.cache.block.count	8	Number of blocks to cache UPDATE query execution plan against text to speed up execution.
pg.update.cache.row.count	8	Number of rows to cache for UPDATE query execution plan against text to speed up execution.
pg.max.blob.size.on.query	512k	For binary values, clients will receive an error when requesting blob sizes above this value.
pg.recv.buffer.size	1M	Size of the buffer for receiving data.
pg.send.buffer.size	1M	Size of the buffer for sending data.
pg.date.locale	en	The locale to handle date types.
pg.timestamp.locale	en	The locale to handle timestamp types.
pg.worker.count	0	Number of dedicated worker threads assigned to handle PostgreSQL Wire Protocol queries. When 0, the jobs will use the shared pool.
pg.worker.affinity		Comma-separated list of thread numbers which should be pinned for Postgres ingestion. Example pg.worker.affinity=1,2,3.
pg.halt.on.error	false	Whether ingestion should stop upon internal error.
pg.daemon.pool	true	Defines whether to run all PostgreSQL Wire Protocol worker threads in daemon mode (true) or not (false).
pg.binary.param.count.capacity	2	Size of the initial capacity for the pool used for binary bind variables.

InfluxDB Line Protocol (ILP)

This section describes ingestion settings for incoming messages using InfluxDB line protocol.

Property	Default	Description
line.default.partition.by	DAY	Table partition strategy to be used with tables that are created automatically by InfluxDB Line Protocol. Possible values are: HOUR, DAY, WEEK, MONTH, and YEAR.

HTTP specific settings

Property	Default	Description
line.http.enabled	true	Enable ILP over HTTP. Default port is 9000. Enabled by default within open source versions, defaults to false and must be enabled for Enterprise.
line.http.ping.version	v2.2.2	Version information for the ping response of ILP over HTTP.
HTTP properties	Various	See HTTP settings for general HTTP configuration. ILP over HTTP inherits from HTTP settings.

TCP specific settings

Property	Default	Description
line.tcp.enabled	true	Enable or disable line protocol over TCP.
line.tcp.net.bind.to	0.0.0.0:9009	IP address of the network interface to bind listener to and port. By default, TCP receiver listens on all network interfaces.
line.tcp.net.connection.limit	256	The maximum number permitted for simultaneous connections to the server. This value is intended to control server memory consumption.
line.tcp.net.connection.timeout	300000	Connection idle timeout in milliseconds. Connections are closed by the server when this timeout lapses.
line.tcp.net.connection.hint	false	Windows specific flag to overcome OS limitations on TCP backlog size
line.tcp.net.connection.rcvbuf	-1	Maximum buffer receive size on each TCP socket. If value is -1, the socket receive buffer remains unchanged from OS default.
line.tcp.net.connection.queue.timeout	5000	Amount of time in milliseconds a connection can wait in the listen backlog queue before its refused. Connections will be aggressively removed from the backlog until the active connection limit is breached.
line.tcp.auth.db.path		Path which points to the authentication db file.
line.tcp.connection.pool.capacity	64	The maximum amount of pooled connections this interface may have.
line.tcp.timestamp	n	Input timestamp resolution. Possible values are n, u, ms, s and h.
line.tcp.msg.buffer.size	32768	Size of the buffer read from queue. Maximum size of write request, regardless of the number of measurements.
line.tcp.maintenance.job.interval	1000	Maximum amount of time (in milliseconds) between maintenance jobs committing any uncommitted data on inactive tables.
line.tcp.min.idle.ms.before.writer.release	500	Minimum amount of idle time (in milliseconds) before a table writer is released.
line.tcp.commit.interval.fraction	0.5	Commit lag fraction. Used to calculate commit interval for the table according to the following formula: commit_interval = commit_lag ∗ fraction. The calculated commit interval defines how long uncommitted data will need to remain uncommitted.
line.tcp.commit.interval.default	1000	Default commit interval in milliseconds.
line.tcp.max.measurement.size	32768	Maximum size of any measurement.
line.tcp.writer.queue.size	128	Size of the queue between network I/O and writer jobs. Each queue entry represents a measurement.
line.tcp.writer.worker.count		Number of dedicated I/O worker threads assigned to write data to tables. When 0, the writer jobs will use the shared pool.
line.tcp.writer.worker.affinity		Comma-separated list of thread numbers which should be pinned for line protocol ingestion over TCP. CPU core indexes are 0-based.
line.tcp.writer.worker.sleep.threshold	1000	Amount of subsequent loop iterations with no work done before the worker goes to sleep.
line.tcp.writer.worker.yield.threshold	10	Amount of subsequent loop iterations with no work done before the worker thread yields.
line.tcp.writer.queue.capacity	128	Size of the queue between the IO jobs and the writer jobs, each queue entry represents a measurement.
line.tcp.writer.halt.on.error	false	Flag that indicates if the worker thread must stop when an unexpected error occurs.
line.tcp.io.worker.count		Number of dedicated I/O worker threads assigned to parse TCP input. When 0, the writer jobs will use the shared pool.
line.tcp.io.worker.affinity		Comma-separated list of thread numbers which should be pinned for line protocol ingestion over TCP. CPU core indexes are 0-based.
line.tcp.io.worker.sleep.threshold	1000	Amount of subsequent loop iterations with no work done before the worker goes to sleep.
line.tcp.io.worker.yield.threshold	10	Amount of subsequent loop iterations with no work done before the worker thread yields.
line.tcp.disconnect.on.error	true	Disconnect TCP socket that sends malformed messages.

UDP specific settings

note

The UDP receiver is deprecated since QuestDB version 6.5.2. We recommend the InfluxDB Line Protocol TCP receiver instead.

Property	Default	Description
line.udp.join	232.1.2.3	Multicast address receiver joins. This values is ignored when receiver is in "unicast" mode.
line.udp.bind.to	0.0.0.0:9009	IP address of the network interface to bind listener to and port. By default UDP receiver listens on all network interfaces.
line.udp.commit.rate	1000000	For packet bursts the number of continuously received messages after which receiver will force commit. Receiver will commit irrespective of this parameter when there are no messages.
line.udp.msg.buffer.size	2048	Buffer used to receive single message. This value should be roughly equal to your MTU size.
line.udp.msg.count	10000	Only for Linux. On Linux, QuestDB will use the recvmmsg() system call. This is the max number of messages to receive at once.
line.udp.receive.buffer.size	8388608	UDP socket buffer size. Larger size of the buffer will help reduce message loss during bursts.
line.udp.enabled	false	Enable or disable UDP receiver.
line.udp.own.thread	false	When true, UDP receiver will use its own thread and busy spin that for performance reasons. "false" makes receiver use worker threads that do everything else in QuestDB.
line.udp.own.thread.affinity	-1	-1 does not set thread affinity. OS will schedule thread and it will be liable to run on random cores and jump between the. 0 or higher pins thread to give core. This property is only valid when UDP receiver uses own thread.
line.udp.unicast	false	When true, UDP will use unicast. Otherwise multicast.
line.udp.timestamp	n	Input timestamp resolution. Possible values are n, u, ms, s and h.
line.udp.commit.mode	nosync	Commit durability. Available values are nosync, sync and async.

Database replication

note

Replication is Enterprise only.

Replication enables high availability clusters.

For setup instructions, see the replication operations guide.

For an overview of the concept, see the replication concept page.

For a tuning guide see... the replication tuning guide.

Property	Default	Description
replication.role	none	Defaults to none for stand-alone instances. To enable replication set to one of: primary, replica.
replication.object.store		A configuration string that allows connecting to an object store. The format is scheme::key1=value;key2=value2;…. The various keys and values are detailed in a later section. Ignored if replication is disabled. No default given variability.
cairo.wal.segment.rollover.size	2097152	The size of the WAL segment before it is rolled over. Default is 2MiB. However, defaults to 0 unless replication.role=primary is set.
cairo.writer.command.queue.capacity	32	Maximum writer ALTER TABLE and replication command capacity. Shared between all the tables.
replication.primary.throttle.window.duration	10000	The millisecond duration of the sliding window used to process replication batches. Default is 10000 ms.
replication.requests.max.concurrent	0	A limit to the number of concurrent object store requests. The default is 0 for unlimited.
replication.requests.retry.attempts	3	Maximum number of times to retry a failed object store request before logging an error and reattempting later after a delay. Default is 3.
replication.requests.retry.interval	200	How long to wait before retrying a failed operation. Default is 200 ms.
replication.primary.compression.threads	calculated	Max number of threads used to perform file compression operations before uploading to the object store. The default value is calculated as half the number of CPU cores.
replication.primary.compression.level	1	Zstd compression level. Defaults to 1. Valid values are from 1 to 22.
replication.replica.poll.interval	1000	Millisecond polling rate of a replica instance to check for the availability of new changes.
native.async.io.threads	cpuCount	The number of async (network) io threads used for replication (and in the future cold storage). The default should be appropriate for most use cases.
native.max.blocking.threads	cpuCount * 4	Maximum number of threads for parallel blocking disk IO read/write operations for replication (and other). These threads are ephemeral: They are spawned per need and shut down after a short duration if no longer in use. These are not cpu-bound threads, hence the relative large number. The default should be appropriate for most use cases.

OpenID Connect (OIDC)

note

OpenID Connect is Enterprise and Cloud only.

Integrate with OpenID Connect (OIDC) to sync QuestDB with an Identity Provider (IdP).

For a full explanation of OIDC, see the OpenID Connect (OIDC) integration guide.

Property	Default	Description
acl.oidc.enabled		Enables/disables OIDC authentication. When enabled, few other configuration options must also be set.
acl.oidc.host		OIDC provider hostname, required when OIDC is enabled.
acl.oidc.port	443	OIDC provider port number, required when OIDC is enabled.
acl.oidc.tls.enabled		Whether the OIDC provider requires a secure connection or not. It is highly unlikely, but if the User Info Endpoint does not require a secure connection, this option can be set to false.
acl.oidc.tls.validation.enabled		Enables/disables TLS certificate validation. If you are working with self-signed certificates that you would like QuestDB to trust, disable this option. Validation is strongly recommended in production environments. QuestDB will check that the certificate is valid, and that it is issued for the server to which it connects.
acl.oidc.tls.keystore.path		Path to a keystore file that contains trusted Certificate Authorities. Will be used when validating the certificate of the OIDC provider. Not required if your OIDC provider's certificate is signed by a public CA.
acl.oidc.tls.keystore.password		Keystore password, required if there is a keystore file and it is password protected.
acl.oidc.http.timeout	30000	OIDC provider HTTP request timeout in milliseconds.
acl.oidc.client.id		Client name assigned to QuestDB in the OIDC server, required when OIDC is enabled.
acl.oidc.authorization.endpoint	/as/authorization.oauth2	OIDC Authorization Endpoint, the default value should work for the Ping Identity Platform.
acl.oidc.token.endpoint	/as/token.oauth2	OIDC Token Endpoint, the default value should work for the Ping Identity Platform.
acl.oidc.userinfo.endpoint	/idp/userinfo.openid	OIDC User Info Endpoint, the default value should work for the Ping Identity Platform.
acl.oidc.groups.claim	groups	The name of the custom claim inside the user info response object, which contains the group memberships of the user.
acl.oidc.cache.ttl	30000	User info cache entry TTL (time to live) in milliseconds, default value is 30 seconds. For improved performance QuestDB caches user info responses for each valid access token, this settings drives how often the access token should be validated and the user info updated.

Config Validation

The database startup phase checks for configuration issues, such as invalid or deprecated settings. Issues may be classified as advisories or errors. Advisory issues are logged without causing the database to stop its startup sequence: These are usually setting deprecation warnings. Configuration errors can optionally cause the database to fail its startup.

Property	Default	Description
config.validation.strict	false	When enabled, startup fails if there are configuration errors.

We recommended enabling strict validation.

Telemetry

QuestDB sends anonymous telemetry data with information about usage which helps us improve the product over time. We do not collect any personally-identifying information, and we do not share any of this data with third parties.

Property	Default	Description
telemetry.enabled	true	Enable or disable anonymous usage metrics collection.
telemetry.hide.tables	false	Hides telemetry tables from select * from tables() output. As a result, telemetry tables will not be visible in the Web Console table view.
telemetry.queue.capacity	512	Capacity of the internal telemetry queue, which is the gateway of all telemetry events. This queue capacity does not require tweaking.

Logging & Metrics

For logging information with log.conf and for how to enable metrics with Prometheus, see Logging & Metrics.