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:

  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 keyenv var
shared.worker.countQDB_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 QBD_SHARED_WORKER_COUNT=5

Docker#

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

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

This publishes the following ports:

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 QBD_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):/root/.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):/root/.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.

Shared worker#

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

PropertyDefaultDescription
shared.worker.count2Number of worker threads shared across the application. Increasing this number will increase parallelism in the application at the expense of CPU resources.
shared.worker.affinityComma-delimited list of CPU ids, one per thread specified in shared.worker.count. By default, threads have no CPU affinity.
shared.worker.haltOnErrorfalseToggle whether worker should stop on error.

Load balancing#

This section describes configuration settings for the distribution of work by writer threads in a QuestDB instance.

PropertyDefaultDescription
line.tcp.n.updates.per.load.balance10000Maximum number of updates in a given table since the last load balancing before triggering a new load balancing job.
line.tcp.max.load.ratio1.9Maximum load ratio (max loaded worker/min loaded worker) before QuestDB will attempt to rebalance the load between the writer workers.
line.tcp.max.uncommitted.rows1000Maximum number of uncommitted rows, note that rows will always be committed if they have been received line.tcp.maintenance.job.interval ms ago.
line.tcp.maintenance.job.interval1000Maximum amount of time in between maintenance jobs, these will commit any uncommitted data.

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.

Examples of how to use this server, along with expected responses, can be found on the health monitoring page.

PropertyDefaultDescription
http.min.enabledtrueEnable Minimal HTTP server.
http.min.bind.to0.0.0.0:9003IPv4 address and port of the server. 0 means it will bind to all network interfaces. Otherwise IP address must by one of the existing network adaptors

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.

PropertyDefaultDescription
http.enabledtrueEnable HTTP server.
http.connection.pool.initial.capacity16Initial 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.capacity128Initial size of the string pool shared by HttpHeaderParser and HttpMultipartContentParser.
http.multipart.header.buffer.size512HeaderParser buffer size in bytes.
http.multipart.idle.spin.count10_000How long the code accumulates incoming data chunks for column and delimiter analysis.
http.receive.buffer.size1mSize of receive buffer.
http.request.header.buffer.size64kSize of internal buffer allocated for HTTP request headers. The value is rounded up to the nearest power of 2. When HTTP request contains headers that exceed the buffer size server will disconnect the client with HTTP error in server log.
http.response.header.buffer.size32kSize 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.count0Number of threads in private worker pool. When value is 0, HTTP server will be using shared worker pool of the server. Values above 0 switch on private pool.
http.worker.affinitycomma separated list of CPU core indexes. The number of items of this list must be equal to the worker count.
http.worker.haltOnErrorfalseFlag that indicates if worker thread must shutdown on unhandled error. We strongly recommend not to change default value.
http.send.buffer.size2mSize of the internal send buffer. The larger than buffer size the fewer IO interruptions server is making at 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.nameindex.htmlName of index file for the Web Console.
http.frozen.clockfalseSets the clock to always return zero. This configuration parameter is used for internal testing.
http.allow.deflate.before.sendfalseEnable / disable Gzip compression of outgoing data.
http.keep-alive.timeout5Used 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.max10_000See http.keep-alive.timeout. Has to be 0 when http.version is set to HTTP/1.0.
http.static.public.directorypublicThe name of directory for public web site.
http.net.active.connection.limit256The number of simultaneous TCP connection to the HTTP server. The rationale of the value is to control server memory consumption.
http.net.event.capacity1024Internal IO event queue capacity (EPoll, KQqueu, Select). Size of these queues must be larger than http.net.active.connection.limit.
http.net.io.queue.capacity1024Internal IO queue of HTTP server. Size of this queue must be larger than http.net.active.connection.limit. Queue size smaller than active connection max will substantially slow down the server by increasing wait times. Queue larger than connection max reduces wait time to 0.
http.net.idle.connection.timeout300000TCP connection idle timeout in milliseconds. Connection is closed by HTTP server when this timeout lapses.
http.net.interest.queue.capacity1024Internal queue size. This is also related to http.net.active.connection.limit in a way that sizes larger than connection max remove any waiting.
http.net.listen.backlog256Backlog argument value for listen() call.
http.net.snd.buf.size2mMaximum send buffer size on each TCP socket. If value is -1 socket send buffer remains unchanged from OS default.
http.net.rcv.buf.size2mMaximum receive buffer size on each TCP socket. If value is -1 socket receive buffer remains unchanged from OS default.
http.text.date.adapter.pool.capacity16Size of date adaptor 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.limit16384JSON 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.size8192Initial 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.stddev0.1222dThe 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.stddev0.8Maximum 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.capacity128The 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.limit4mThe limit of text roll buffer. See http.text.roll.buffer.size for description.
http.text.roll.buffer.size1024Roll buffer is a structure in 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.lines1000Number 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.capacity64The 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.capacity64Size of timestamp adaptor 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.size4096Initial size of UTF-8 adaptor sink. The value should correspond the maximum individual field value length in text input
http.json.query.connection.check.frequency1_000_000The value to throttle check if client socket has been disconnected. It is not recommended to change this value
http.json.query.float.scale10The scale value of string representation of FLOAT values
http.json.query.double.scale12The scale value of string representation of DOUBLE values
http.bind.to0.0.0.0:9000IP address and port of HTTP server. 0 means that http server will bind to all network interfaces. You can specify IP address of any individual network interface on your system
http.security.readonlyfalseForces HTTP read only mode when true, which disables commands which modify the data or data structure.
http.security.max.response.rowsLong.MAX_VALUELimit the number of response rows over HTTP.
http.security.interrupt.on.closed.connectiontrueSwitch to enable termination of SQL processing if the HTTP connection is closed. The mechanism affects performance so the connection is only checked after http.security.interruptor.iterations.per.check 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, http.security.interruptor.buffer.size denotes the size of the buffer for this.
http.security.interruptor.iterations.per.check2000000Number of internal iterations such as loops over data before checking if the HTTP connection is still open
http.security.interruptor.buffer.size32Size 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.alivetrueIf set to false, the server will disconnect the client after completion of each request.
http.versionHTTP/1.1Protocol version, other supported value is HTTP/1.0.

Cairo engine#

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

PropertyDefaultDescription
cairo.sql.copy.rootnullInput root directory for CSV imports via copy SQL.
cairo.sql.backup.rootnullOutput root directory for backups.
cairo.sql.backup.dir.datetime.formatnullDate format for backup directory.
cairo.sql.backup.dir.tmp.nametmpName of tmp directory used during backup.
cairo.sql.backup.mkdir.mode509Permission used when creating backup directories.
cairo.rootdbDirectory for storing db tables and metadata. This directory is inside the server root directory provided at startup.
cairo.commit.modenosyncHow changes to table are flushed to disk upon commit. Choices: nosync, async (flush call schedules update, returns immediately), sync (waits for flush to complete).
cairo.create.as.select.retry.count5Number of types table creation or insertion will be attempted.
cairo.default.map.typefastType of map used. Options: fast (speed at the expense of storage), compact.
cairo.default.symbol.cache.flagfalseWhen true, symbol values will be cached on Java heap.
cairo.default.symbol.capacity256Specifies 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.count30Number of attempts to open files.
cairo.idle.check.interval300000Frequency of writer maintenance job in milliseconds.
cairo.inactive.reader.ttl-120000Frequency of reader pool checks for inactive readers in milliseconds.
cairo.inactive.writer.ttl-600000Frequency of writer pool checks for inactive writers in milliseconds.
cairo.index.value.block.size256Approximation of number of rows for a single index key, must be power of 2.
cairo.max.swap.file.count30Number of attempts to open swap files.
cairo.mkdir.mode509File permission mode for new directories.
cairo.parallel.index.threshold100000Minimum number of rows before allowing use of parallel indexation.
cairo.reader.pool.max.segments5Number of attempts to get TableReader.
cairo.spin.lock.timeout1_000_000Timeout when attempting to get BitmapIndexReaders in microseconds.
cairo.cache.rows16Number of rows for the query cache.
cairo.cache.blocks4Number of blocks for the query cache.
cairo.character.store.capacity1024Size of the CharacterStore.
cairo.character.store.sequence.pool.capacity64Size of the CharacterSequence pool.
cairo.column.pool.capacity4096Size of the Column pool in the SqlCompiler.
cairo.compact.map.load.factor0.7Load factor for CompactMaps.
cairo.expression.pool.capacity8192Size of the ExpressionNode pool in SqlCompiler.
cairo.fast.map.load.factor0.5Load factor for all FastMaps.
cairo.sql.join.context.pool.capacity64Size of the JoinContext pool in SqlCompiler.
cairo.lexer.pool.capacity2048Size of FloatingSequence pool in GenericLexer.
cairo.sql.map.key.capacity2mKey capacity in FastMap and CompactMap.
cairo.sql.map.max.resizes2^31Number of map resizes in FastMap and CompactMap before a resource limit exception is thrown, each resize doubles the previous size.
cairo.sql.map.page.size4mMemory page size for FastMap and CompactMap.
cairo.sql.map.max.pages2^31Memory max pages for CompactMap.
cairo.model.pool.capacity1024Size of the QueryModel pool in the SqlCompiler.
cairo.sql.sort.key.page.size4mMemory page size for storing keys in LongTreeChain.
cairo.sql.sort.key.max.pages2^31Max number of pages for storing keys in LongTreeChain before a resource limit exception is thrown.
cairo.sql.sort.light.value.page.size1048576Memory page size for storing values in LongTreeChain.
cairo.sql.sort.light.value.max.pages2^31Max pages for storing values in LongTreeChain.
cairo.sql.hash.join.value.page.size16777216Memory page size of the slave chain in full hash joins.
cairo.sql.hash.join.value.max.pages2^31Max pages of the slave chain in full hash joins.
cairo.sql.latest.by.row.count1000Number of rows for LATEST BY.
cairo.sql.hash.join.light.value.page.size1048576Memory page size of the slave chain in light hash joins.
cairo.sql.hash.join.light.value.max.pages2^31Max pages of the slave chain in light hash joins.
cairo.sql.sort.value.page.size16777216Memory page size of file storing values in SortedRecordCursorFactory.
cairo.sql.sort.value.max.pages2^31Max pages of file storing values in SortedRecordCursorFactory.
cairo.work.steal.timeout.nanos10_000Latch await timeout in nanos for stealing indexing work from other threads.
cairo.parallel.indexing.enabledtrueAllows parallel indexation. Works in conjunction with cairo.parallel.index.threshold.
cairo.sql.join.metadata.page.size16384Memory page size for JoinMetadata file.
cairo.sql.join.metadata.max.resizes2^31Number of map resizes in JoinMetadata before a resource limit exception is thrown, each resize doubles the previous size.
cairo.sql.analytic.column.pool.capacity64Size of AnalyticColumn pool in SqlParser.
cairo.sql.create.table.model.pool.capacity16Size of CreateTableModel pool in SqlParser.
cairo.sql.column.cast.model.pool.capacity16Size of CreateTableModel pool in SqlParser.
cairo.sql.rename.table.model.pool.capacity16Size of RenameTableModel pool in SqlParser.
cairo.sql.with.clause.model.pool.capacity128Size of WithClauseModel pool in SqlParser.
cairo.sql.insert.model.pool.capacity64Size of InsertModel pool in SqlParser.
cairo.sql.copy.model.pool.capacity32Size of CopyModel pool in SqlParser.
cairo.sql.copy.buffer.size2mSize of buffer used when copying tables.
cairo.sql.double.cast.scale12Maximum number of decimal places that types cast as doubles have
cairo.sql.float.cast.scale4Maximum number of decimal places that types cast as floats have
cairo.sql.copy.formats.file/text_loader.jsonName of file with user's set of date and timestamp formats.
cairo.date.localeenThe locale to handle date types
cairo.timestamp.localeenThe locale to handle timestamp types

Postgres wire protocol#

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

PropertyDefaultDescription
pg.enabledtrueConfiguration for enabling or diabling the Postres interface
pg.net.active.connection.limit10The number of simultaneous PostgreSQL connections to the server. This value is intended to control server memory consumption.
pg.net.bind.to0.0.0.0:8812IP address and port of PostgreSQL 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.event.capacity1024Internal IO event queue capacity (EPoll, KQqueu, Select). Size of these queues must be larger than active.connection.limit
pg.net.io.queue.capacity1024Internal IO queue of the server. The size of this queue must be larger than the active.connection.limit. A queue size smaller than active connection max will substantially slow down the server by increasing wait times. A queue larger than connection max reduces wait time to 0.
pg.net.idle.timeout300000Connection idle timeout in milliseconds. Connections are closed by the server when this timeout lapses.
pg.net.interest.queue.capacity1024Internal queue size. This is also related to active.connection.limit in a way that sizes larger than connection max remove any waiting.
pg.net.listen.backlog50000Backlog argument value for listen() call.
pg.net.recv.buf.size-1Maximum send buffer size on each TCP socket. If value is -1 socket send buffer remains unchanged from OS default.
pg.net.send.buf.size-1Maximum receive buffer size on each TCP socket. If value is -1, the socket receive buffer remains unchanged from OS default.
pg.character.store.capacity4096Size of the CharacterStore
pg.character.store.pool.capacity64Size of the CharacterStore pool capacity
pg.connection.pool.capacity64The maximum amount of pooled connections this interface may have
pg.passwordquestPostgres database password
pg.useradminPostgres database username
pg.factory.cache.column.count16Number of columns to cache SQL execution plan against text to speed up execution. This value must be 2n (power of two).
pg.factory.cache.row.count16Number of rows to cache for SQL execution plan against text to speed up execution. This value must be 2n (power of two)
pg.idle.recv.count.before.giving.up10000Number of times to poll receive method that returns zero data before deciding what to do next with the connection
pg.idle.send.count.before.giving.up10000Number of times to poll send method that returns zero data before deciding what to do next with the connection
pg.max.blob.size.on.query512kFor binary values, clients will receive an error when requesting blob sizes above this value
pg.recv.buffer.size1MSize of the buffer for receiving data
pg.send.buffer.size1MSize of the buffer for sending data
pg.date.localeenThe locale to handle date types
pg.timestamp.localeenThe locale to handle timestamp types
pg.worker.count2Number of dedicated worker threads assigned to write data. When 0, the writer jobs will use the shared pool.
pg.worker.affinity-1,-1Comma-separated list of thread numbers which should be pinned for Postgres ingestion. Example line.tcp.worker.affinity=1,2,3.
pg.halt.on.errorfalseWhether ingestion should stop upon internal error

InfluxDB line protocol (TCP)#

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

PropertyDefaultDescription
line.tcp.enabledtrueEnable or disable line protocol over TCP.
line.tcp.net.active.connection.limit10The number of simultaneous connections to the server. This value is intended to control server memory consumption.
line.tcp.net.bind.to0.0.0.0:9009IP address of the network interface to bind listener to and port. By default, TCP receiver listens on all network interfaces.
line.tcp.net.event.capacity1024Internal IO event queue capacity (EPoll, KQqueu, Select). Size of these queues must be larger than active.connection.limit.
line.tcp.net.io.queue.capacity1024Internal IO queue of the server. The size of this queue must be larger than the active.connection.limit. A queue size smaller than active connection max will substantially slow down the server by increasing wait times. A queue larger than connection max reduces wait time to 0.
line.tcp.auth.db.pathPath which points to the authentication db file.
line.tcp.net.idle.timeout300000Connection idle timeout in milliseconds. Connections are closed by the server when this timeout lapses.
line.tcp.default.partition.byDAYThe default partitioning strategy applied to new tables dynamically created by sending records via ILP created
line.tcp.net.interest.queue.capacity1024Internal queue size. This is also related to active.connection.limit in a way that sizes larger than connection max remove any waiting.
line.tcp.net.listen.backlog50000Backlog argument value for listen() call.
line.tcp.net.recv.buf.size-1Maximum buffer receive size on each TCP socket. If value is -1, the socket receive buffer remains unchanged from OS default.
line.tcp.net.snd.buf.size-1Maximum buffer send size on each TCP socket. If value is -1, the socket receive buffer remains unchanged from OS default.
line.tcp.connection.pool.capacity64The maximum amount of pooled connections this interface may have
line.tcp.timestampnInput timestamp resolution. Possible values are n, u, ms, s and h.
line.tcp.msg.buffer.size2048Size of the buffer read from queue. Maximum size of write request, regardless of the number of measurements.
line.tcp.max.measurement.size2048Maximum size of any measurement.
line.tcp.writer.queue.size128Size of the queue between network IO and writer jobs. Each queue entry represents a measurement.
line.tcp.io.worker.count0Number of dedicated worker threads assigned to write data. When 0, the writer jobs will use the shared pool.
line.tcp.io.worker.affinity0Comma-separated list of thread numbers which should be pinned for line protocol ingestion over TCP. Example line.tcp.worker.affinity=1,3,4.
line.tcp.halt.on.errorfalseWhether ingestion should stop upon internal error

InfluxDB line protocol (UDP)#

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

PropertyDefaultDescription
line.udp.join232.1.2.3Multicast address receiver joins. This values is ignored when receiver is in "unicast" mode.
line.udp.bind.to0.0.0.0:9009IP address of the network interface to bind listener to and port. By default UDP receiver listens on all network interfaces.
line.udp.commit.rate1000000For 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.size2048Buffer used to receive single message. This value should be roughly equal to your MTU size.
line.udp.msg.count10000Only for Linux. On Linix QuestDB will use recvmmsg(). This is the max number of messages to receive at once.
line.udp.receive.buffer.size8388608UDP socket buffer size. Larger size of the buffer will help reduce message loss during bursts.
line.udp.enabledtrueFlag to enable or disable UDP receiver.
line.udp.own.threadfalseWhen "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.unicastfalseWhen true, UDP will me unicast. Otherwise multicast.
line.udp.timestampnInput timestamp resolution. Possible values are n, u, ms, s and h.
line.udp.commit.modenosyncCommit durability. Available values are nosync, sync and async.

Telemetry#

QuestDB sends anonymized 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.

PropertyDefaultDescription
telemetry.enabledtrueEnable / 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 file named log-stdout.conf.

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

QuestDB will look for /log-stdout.conf on the classpath unless this name is overridden via a "system" property: -Dout=/something_else.conf.

Docker#

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):/root/.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.

Environment variables#

Values in the log-stdout.conf 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
Setting log level to ERROR via environment variable
export QDB_LOG_W_STDOUT_LEVEL=ERROR

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.