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 configuration file and the environment variables, the default value is used. Configuration of logging is handled separately and details of configuring this behavior can be found at the logging section below.

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:

QDB_ prefix
uppercase characters
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

Docker#

This section describes how to configure QuestDB server settings when running QuestDB in a Docker container. A command to run QuestDB via Docker with default interfaces is as follows:

Example of running docker container with built-in storage

docker run -p 9000:9000 \
 -p 9009:9009 \
 -p 8812:8812 \
 -p 9003:9003 \
 questdb/questdb

This publishes the following ports:

-p 9000:9000 - REST API and Web Console
-p 9009:9009 - InfluxDB line protocol
-p 8812:8812 - Postgres wire protocol
-p 9003:9003 - Min health server and Prometheus metrics

The examples in this section change the default HTTP and REST API port from 9000 to 4000 for illustrative purposes, and demonstrate how to publish this port with a non-default property.

Environment variables#

Server configuration can be passed to QuestDB running in Docker by using the -e flag to pass an environment variable to a container:

docker run -p 4000:4000 -e QDB_HTTP_BIND_TO=0.0.0.0:4000 questdb/questdb

Mounting a volume#

A server configuration file can be provided by mounting a local directory in a QuestDB container. Given the following configuration file which overrides the default HTTP bind property:

./server.conf

http.bind.to=0.0.0.0:4000

Running the container with the -v flag allows for mounting the current directory to QuestDB's conf directory in the container. With the server configuration above, HTTP ports for the web console and REST API will be available on localhost:4000:

docker run -v "$(pwd):/var/lib/questdb/conf" -p 4000:4000 questdb/questdb

To mount the full root directory of QuestDB when running in a Docker container, provide a the configuration in a conf directory:

./conf/server.conf

http.bind.to=0.0.0.0:4000

Mount the current directory using the -v flag:

docker run -v "$(pwd):/var/lib/questdb/" -p 4000:4000 questdb/questdb

The current directory will then have data persisted to disk:

Current directory contents

├── conf
│  └── server.conf
├── db
└── public

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	Toggle whether worker should stop on error.

Minimal HTTP server#

This server runs embedded in a QuestDB instance by default and enables health checks of an instance via HTTP. It responds to all requests with a HTTP status code of 200 unless the QuestDB process dies.

info

Port 9003 also provides a /metrics endpoint with Prometheus metrics exposed. Examples of how to use the min server and Prometheus endpoint can be found on the health monitoring page.

Property	Default	Description
http.min.enabled	true	Enable or disable Minimal HTTP server.
http.min.bind.to	0.0.0.0:9003	IPv4 address and port of the server. `0` means it will bind to all network interfaces, otherwise the IP address must be one of the existing network adapters.
http.min.net.connection.limit	4	Active connection limit.
http.min.net.connection.timeout	300000	Idle connection timeout is milliseconds.
http.min.net.connection.hint	false	Windows specific flag to overcome OS limitations on TCP backlog size.
http.min.worker.count		By default, minimal HTTP server uses shared thread pool for CPU core count 16 and below. It will use dedicated thread for core count above 16. When `0`, the server will use the shared pool. Do not set pool size to more than `1`.
http.min.worker.affinity		Core number to pin thread to.

HTTP server#

This section describes configuration settings for the Web Console 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.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.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 worker thread must shutdown on unhandled error.
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.
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.
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.commit.lag (QuestDB 6.5.5 and earlier)	10 minutes	Expected maximum time lag for out-of-order rows in milliseconds.
cairo.o3.max.lag (QuestDB 6.6 and later)	10 minutes	The maximum size of in-memory buffer in milliseconds. The buffer is allocated dynamically through analysing the shape of the incoming data, and `o3MaxLag` is the upper 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.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	Frequency of reader pool checks for inactive readers in milliseconds.
cairo.inactive.writer.ttl	-600000	Frequency of writer pool checks for 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	5	Number of attempts to get TableReader.
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.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.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.date.locale	en	The locale to handle date types.
cairo.timestamp.locale	en	The locale to handle timestamp types.
cairo.o3.column.memory.size	8M	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 2x8M).
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.
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.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.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.system.table.prefix	sys.	Prefix of the tables used for QuestDB internal data storage. These tables are hidden from QuestDB web console.

CSV import#

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

Mandatory settings to enable COPY:

Property	Default	Description
cairo.sql.copy.root	null	Input root directory for CSV imports via `COPY` SQL. This path should not overlap with other directory (e.g. db, conf) of running instance, otherwise import may delete or overwrite existing files.
cairo.sql.copy.work.root	null	Temporary import file directory. Defaults to `root_directory/tmp` if not set explicitly.

Optional settings for COPY:

Property	Default	Description
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.
cairo.page.frame.task.pool.capacity	4	Initial object pool capacity for local reduce tasks. These tasks are used to avoid blocking query execution when the reduce queue is full.

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.security.readonly	false	Forces PGWire 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 PGWire 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.

InfluxDB line protocol#

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

Property	Default	Description
line.default.partition.by	DAY	The default partitioning strategy applied to new tables dynamically created by sending records via ILP.

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.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.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.default.partition.by	DAY	Table partition strategy to be used with tables that are created automatically by ILP. Possible values are: `HOUR`, `DAY`, `MONTH` and `YEAR`
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 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	true	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`.

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.

Logging#

The logging behavior of QuestDB may be set in dedicated configuration files or by environment variables. This section describes how to configure logging using these methods.

Configuration file#

Logs may be configured via a dedicated configuration file log.conf.

log.conf

# list of configured writers
writers=file,stdout

# file writer
#w.file.class=io.questdb.log.LogFileWriter
#w.file.location=questdb-debug.log
#w.file.level=INFO,ERROR

# rolling file writer
#w.file.class=io.questdb.log.LogRollingFileWriter
#w.file.location=${log.dir}/questdb-rolling.log.${date:yyyyMMdd}
#w.file.level=INFO,ERROR
#rollEvery accepts: day, hour, minute, month
#w.file.rollEvery=day
#w.file.rollSize=1g

# stdout
w.stdout.class=io.questdb.log.LogConsoleWriter
w.stdout.level=INFO,ERROR

QuestDB will look for /log.conf first in conf/ directory and then on the classpath unless this name is overridden via a command line property: -Dout=/something_else.conf. QuestDB will create conf/log.conf using default values If -Dout is not set and file doesn't exist .

On Windows log messages go to depending on run mode :

interactive session - console and $dataDir\log\stdout-%Y-%m-%dT%H-%M-%S.txt (default is .\log\stdout-%Y-%m-%dT%H-%M-%S.txt )
service - $dataDir\log\service-%Y-%m-%dT%H-%M-%S.txt (default is C:\Windows\System32\qdbroot\log\service-%Y-%m-%dT%H-%M-%S.txt )

Environment variables#

Values in the log configuration file can be overridden with environment variables. All configuration keys must be formatted as described in the environment variables section above.

For example, to set logging on ERROR level only:

Setting log level to ERROR in log-stdout.conf

w.stdout.level=ERROR

This can be passed as an environment variable as follows:

Setting log level to ERROR via environment variable

export QDB_LOG_W_STDOUT_LEVEL=ERROR

Configuring Docker logging#

When mounting a volume to a Docker container, a logging configuration file may be provided in the container located at ./conf/log.conf. For example, a file with the following contents can be created:

./conf/log.conf

# list of configured writers
writers=file,stdout,http.min

# file writer
w.file.class=io.questdb.log.LogFileWriter
w.file.location=questdb-docker.log
w.file.level=INFO,ERROR,DEBUG

# stdout
w.stdout.class=io.questdb.log.LogConsoleWriter
w.stdout.level=INFO

# min http server, used monitoring
w.http.min.class=io.questdb.log.LogConsoleWriter
w.http.min.level=ERROR
w.http.min.scope=http-min-server

The current directory can be mounted:

Mount the current directory to a QuestDB container

docker run -p 9000:9000 -v "$(pwd):/var/lib/questdb/" questdb/questdb

The container logs will be written to disk using the logging level and file name provided in the ./conf/log.conf file, in this case in ./questdb-docker.log.

Prometheus Alertmanager#

QuestDB includes a log writer that sends any message logged at critical level (logger.critical("may-day")) to Prometheus Alertmanager over a TCP/IP socket. Details for configuring this can be found in the Prometheus documentation. To configure this writer, add it to the writers config alongside other log writers.

log.conf

# Which writers to enable
writers=stdout,alert

# stdout
w.stdout.class=io.questdb.log.LogConsoleWriter
w.stdout.level=INFO

# Prometheus Alerting
w.alert.class=io.questdb.log.LogAlertSocketWriter
w.alert.level=CRITICAL
w.alert.location=/alert-manager-tpt.json
w.alert.alertTargets=localhost:9093,localhost:9096,otherhost:9093
w.alert.defaultAlertHost=localhost
w.alert.defaultAlertPort=9093

# The `inBufferSize` and `outBufferSize` properties are the size in bytes for the
# socket write buffers.
w.alert.inBufferSize=2m
w.alert.outBufferSize=4m
# Delay in milliseconds between two consecutive attempts to alert when
# there is only one target configured
w.alert.reconnectDelay=250

Of all properties, only w.alert.class and w.alert.level are required, the rest assume default values as stated above (except for w.alert.alertTargets which is empty by default).

Alert targets are specified using w.alert.alertTargets as a comma-separated list of up to 12 host:port TCP/IP addresses. Specifying a port is optional and defaults to the value of defaultAlertHost. One of these alert managers is picked at random when QuestDB starts, and a connection is created.

All alerts will be sent to the chosen server unless it becomes unavailable. If it is unavailable, the next server is chosen. If there is only one server configured and a fail-over cannot occur, a delay of 250 milliseconds is added between send attempts.

The w.alert.location property refers to the path (absolute, otherwise relative to -d database-root) of a template file. By default, it is a resource file which contains:

/alert-manager-tpt.json

[
  {
    "Status": "firing",
    "Labels": {
      "alertname": "QuestDbInstanceLogs",
      "service": "QuestDB",
      "category": "application-logs",
      "severity": "critical",
      "version": "${QDB_VERSION}",
      "cluster": "${CLUSTER_NAME}",
      "orgid": "${ORGID}",
      "namespace": "${NAMESPACE}",
      "instance": "${INSTANCE_NAME}",
      "alertTimestamp": "${date: yyyy/MM/ddTHH:mm:ss.SSS}"
    },
    "Annotations": {
      "description": "ERROR/cl:${CLUSTER_NAME}/org:${ORGID}/ns:${NAMESPACE}/db:${INSTANCE_NAME}",
      "message": "${ALERT_MESSAGE}"
    }
  }
]

Four environment variables can be defined, and referred to with the ${VAR_NAME} syntax:

ORGID
NAMESPACE
CLUSTER_NAME
INSTANCE_NAME

Their default value is GLOBAL, they mean nothing outside a cloud environment.

In addition, ALERT_MESSAGE is a placeholder for the actual critical message being sent, and QDB_VERSION is the runtime version of the QuestDB instance sending the alert. The ${date: <format>} syntax can be used to produce a timestamp at the time of sending the alert.

Debug#

QuestDB logging can be quickly forced globally to DEBUG via either providing the java option -Debug or setting the environment variable QDB_DEBUG=true.