Command Line Interface

FoundationDB comes with a command line interface tool called fdbcli. This document describes basic usage of fdbcli and the commands it supports. The use of fdbcli while configuring and administering FoundationDB clusters is described in more detail in the documents on those topics and will be referenced as appropriate.

Invocation at the Command Line

You can invoke fdbcli at the command line simply by typing it. For example:

user@host$ fdbcli
Using cluster file `/etc/foundationdb/fdb.cluster'.

The database is available.

Welcome to the fdbcli. For help, type `help'.

This will result in fdbcli connecting to the default cluster file (/etc/foundationdb/fdb.cluster for Linux.) You can also specify a cluster file as an argument to fdbcli using the -C option. For further information, see Specifying the cluster file.

Commands within fdbcli

The following commands can be issued from within fdbcli at the internal fdb> prompt:


Forces the cluster to recover at the specified version. If the specified version is larger than the current version of the cluster, the cluster version is advanced to the specified version via a forced recovery.


The begin command begins a new transaction. By default, fdbcli operates in autocommit mode. All operations are performed in their own transaction and are automatically committed. By explicitly beginning a transaction, successive operations are all performed as part of a single transaction.

To commit the transaction, use the commit command. To discard the transaction, use the reset command.


The clear command clears a key from the database. Its syntax is clear <KEY>. This command succeeds even if the specified key is not present but may fail due to conflicts.

Note that characters can be escaped when specifying keys (or values) in fdbcli.


The clearrange command clears a range of keys from the database. Its syntax is clearrange <BEGINKEY> <ENDKEY>. All keys between <BEGINKEY> (inclusive) and <ENDKEY> (exclusive) are cleared from the database. This command succeeds even if the specified range is empty but may fail due to conflicts.

Note that characters can be escaped when specifying keys (or values) in fdbcli.


The commit command commits the current transaction. Any sets or clears executed after the start of the current transaction will be committed to the database. On success, the committed version number is displayed. If commit fails, the error is displayed and the transaction must be retried.


The configure command changes the database configuration. Its syntax is configure [new|tss] [single|double|triple|three_data_hall|three_datacenter] [ssd|memory] [grv_proxies=<N>] [commit_proxies=<N>] [resolvers=<N>] [logs=<N>] [count=<TSS_COUNT>] [perpetual_storage_wiggle=<WIGGLE_SPEED>] [perpetual_storage_wiggle_locality=<<LOCALITY_KEY>:<LOCALITY_VALUE>|0>] [storage_migration_type={disabled|aggressive|gradual}] [tenant_mode={disabled|optional_experimental|required_experimental}].

The new option, if present, initializes a new database with the given configuration rather than changing the configuration of an existing one. When new is used, both a redundancy mode and a storage engine must be specified.

The tss option, if present, changes the Testing Storage Server (TSS) configuration for a cluster. When used for the first time, both a count and a storage engine must be specified. For more details, see Testing Storage Server (TSS).

redundancy mode

Redundancy modes define storage requirements, required cluster size, and resilience to failure. The available redundancy modes are:

  • single

  • double

  • triple

  • three_data_hall

  • three_datacenter

For descriptions of redundancy modes, see Choosing a redundancy mode.

storage engine

The storage engine is responsible for durably storing data. FoundationDB has two storage engines:

  • ssd

  • memory

For descriptions of storage engines, see Storage engines.

process types

A FoundationDB cluster employs server processes of different types. It automatically allocates these processes in default numbers appropriate for small-to-medium sized clusters.

For large clusters, you can manually set the allocated number of processes of a given type. Valid process types are:

  • grv_proxies

  • commit_proxies

  • resolvers

  • logs

Set the process using configure [grv_proxies|commit_proxies|resolvers|logs]=<N>, where <N> is an integer greater than 0, or -1 to reset the value to its default.

For recommendations on appropriate values for process types in large clusters, see Guidelines for setting process class.

perpetual storage wiggle

perpetual_storage_wiggle sets the value speed (a.k.a., the number of processes that the Data Distributor should wiggle at a time). Currently, only 0 and 1 are supported. The value 0 means to disable the perpetual storage wiggle. perpetual_storage_wiggle_locality sets the process filter for wiggling. The processes that match the given locality key and locality value are only wiggled. The value 0 will disable the locality filter and matches all the processes for wiggling.

For more details, see Perpetual Storage Wiggle.

storage migration type

Set the storage migration type, or how FDB should migrate to a new storage engine if the value is changed. The default is disabled, which means changing the storage engine will not be possible.

  • disabled

  • gradual

  • aggressive

gradual replaces a single storage at a time when the perpetual storage wiggle is active. This requires the perpetual storage wiggle to be set to a non-zero value to actually migrate storage servers. It is somewhat slow but very safe. This is the recommended method for all production clusters. aggressive tries to replace as many storages as it can at once, and will recruit a new storage server on the same process as the old one. This will be faster, but can potentially hit degraded performance or OOM with two storages on the same process. The main benefit over gradual is that this doesn’t need to take one storage out of rotation, so it works for small or development clusters that have the same number of storage processes as the replication factor. Note that aggressive is not exclusive to running the perpetual wiggle. disabled means that if the storage engine is changed, fdb will not move the cluster over to the new storage engine. This will disable the perpetual wiggle from rewriting storage files.


The consistencycheck command enables or disables consistency checking. Its syntax is consistencycheck [on|off]. Calling it with on enables consistency checking, and off disables it. Calling it with no arguments displays whether consistency checking is currently enabled.

You must be running an fdbserver process with the consistencycheck role to perform consistency checking.


The coordinators command is used to change cluster coordinators or description. Its syntax is coordinators auto|<ADDRESS...> [description=<DESC>].

Addresses may be specified as a list of IP:port pairs (such as coordinators If addresses are specified, the coordinators will be set to them. An fdbserver process must be running on each of the specified addresses.

If auto is specified, coordinator addresses will be chosen automatically to support the configured redundancy level. Processes with class coordinator will be prioritized. (If the current set of coordinators are healthy and already support the configured redundancy level, nothing will be changed.)

For more information on setting coordinators, see Changing coordination servers.

If description=<DESC> is specified, the description field in the cluster file is changed to <DESC>, which must match [A-Za-z0-9_]+.

For more information on setting the cluster description, see Changing the cluster description.


The createtenant command is used to create new tenants in the cluster. Its syntax is createtenant <TENANT_NAME>.

The tenant name can be any byte string that does not begin with the \xff byte. If the tenant already exists, fdbcli will report an error.


The defaulttenant command configures fdbcli to run its commands without a tenant. This is the default behavior.

The active tenant cannot be changed while a transaction (using begin) is open.


The deletetenant command is used to delete tenants from the cluster. Its syntax is deletetenant <TENANT_NAME>.

In order to delete a tenant, it must be empty. To delete a tenant with data, first clear that data using the clear command. If the tenant does not exist, fdbcli will report an error.


The exclude command excludes servers from the database or marks them as failed. Its syntax is exclude [failed] [<ADDRESS...>] [locality_dcid:<excludedcid>] [locality_zoneid:<excludezoneid>] [locality_machineid:<excludemachineid>] [locality_processid:<excludeprocessid>] or any locality. If no addresses are specified, the command provides the set of excluded and failed servers and localities.

For each IP address or IP:port pair in <ADDRESS...> or locality (which include anything set on LocalityData like dcid, zoneid, machineid, processid), the command adds the address/locality to the set of excluded servers and localities. It then waits until all database state has been safely moved off the specified servers.

If the failed keyword is specified, the address is marked as failed and added to the set of failed servers. It will not wait for the database state to move off the specified servers.

For more information on excluding servers, see Removing machines from a cluster.

Warning about potential dataloss failed option: if a server is the last one in some team(s), excluding it with failed will lose all data in the team(s), and hence failed should only be set when the server(s) have permanently failed.

In the case all servers of a team have failed permanently, excluding all the servers will clean up the corresponding keyrange, and fix the invalid metadata. The keyrange will be assigned to a new team as an empty shard.


The exit command exits fdbcli.


The fileconfigure command is alternative to the configure command which changes the configuration of the database based on a json document. The command loads a JSON document from the provided file, and change the database configuration to match the contents of the JSON document.

The format should be the same as the value of the configuration entry in status JSON without excluded_servers or coordinators_count. Its syntax is fileconfigure [new] <FILENAME>.

“The new option, if present, initializes a new database with the given configuration rather than changing the configuration of an existing one.


The force_recovery_with_data_loss command will recover a multi-region database to the specified datacenter. Its syntax is force_recovery_with_data_loss <DCID>. It will likely result in the loss of the most recently committed mutations and is intended to be used if the primary datacenter has been lost.

This command will change the region configuration to have a positive priority for the chosen DCID and a negative priority for all other DCIDs. It will also set usable_regions to 1. If the database has already recovered, this command does nothing.


The get command fetches the value of a given key. Its syntax is get <KEY>. It displays the value of <KEY> if <KEY> is present in the database and not found otherwise.

Note that characters can be escaped when specifying keys (or values) in fdbcli.


The getrange command fetches key-value pairs in a range. Its syntax is getrange <BEGINKEY> [ENDKEY] [LIMIT]. It displays up to <LIMIT> keys and values for keys between <BEGINKEY> (inclusive) and <ENDKEY> (exclusive). If <ENDKEY> is omitted, then the range will include all keys starting with <BEGINKEY>. <LIMIT> defaults to 25 if omitted.

Note that characters can be escaped when specifying keys (or values) in fdbcli.


The getrangekeys command fetches keys in a range. Its syntax is getrangekeys <BEGINKEY> [ENDKEY] [LIMIT]. It displays up to <LIMIT> keys for keys between <BEGINKEY> (inclusive) and <ENDKEY> (exclusive). If <ENDKEY> is omitted, then the range will include all keys starting with <BEGINKEY>. <LIMIT> defaults to 25 if omitted.

Note that characters can be escaped when specifying keys (or values) in fdbcli.


The gettenant command fetches metadata for a given tenant and displays it. Its syntax is gettenant <TENANT_NAME>.

Included in the output of this command are the id and prefix assigned to the tenant. If the tenant does not exist, fdbcli will report an error.


The getversion command fetches the current read version of the cluster or currently running transaction.


The help command provides information on specific commands. Its syntax is help <TOPIC>, where <TOPIC> is any of the commands in this section, escaping, or options. The latter two topics are described below:

help escaping

help escaping provides the following information on escaping keys and values within fdbcli:

When parsing commands, fdbcli considers a space to delimit individual tokens. To include a space in a single value, you may either enclose the token in quotation marks ", prefix the space with a backslash \, or encode the space as a hex character.

To include a literal quotation mark in a token, precede it with a backslash \".

To express a binary value, encode each byte as a two-digit hex value, preceded by \x (e.g. \x20 for a space character, or \x0a\x00\x00\x00 for a 32-bit, little-endian representation of the integer 10).

All keys and values are displayed by fdbcli with non-printable characters and spaces encoded as two-digit hex bytes.

help options

The following options are available for use with the option command:

ACCESS_SYSTEM_KEYS - Allows this transaction to read and modify system keys (those that start with the byte 0xFF).

CAUSAL_READ_RISKY - In the event of a fault or partition, the read version returned may not the last committed version potentially causing you to read outdated data.

CAUSAL_WRITE_RISKY - The transaction, if not self-conflicting, may be committed a second time after commit succeeds, in the event of a fault.

INITIALIZE_NEW_DATABASE - This is a write-only transaction which sets the initial configuration.

NEXT_WRITE_NO_WRITE_CONFLICT_RANGE - The next write performed on this transaction will not generate a write conflict range. As a result, other transactions which read the key(s) being modified by the next write will not conflict with this transaction. Care needs to be taken when using this option on a transaction that is shared between multiple threads. When setting this option, write conflict ranges will be disabled on the next write operation, regardless of what thread it is on.

PRIORITY_BATCH - Specifies that this transaction should be treated as low priority and that default priority transactions should be processed first. Useful for doing batch work simultaneously with latency-sensitive work.

PRIORITY_SYSTEM_IMMEDIATE - Specifies that this transaction should be treated as highest priority and that lower priority transactions should block behind this one. Use is discouraged outside of low-level tools.

READ_AHEAD_DISABLE - Disables read-ahead caching for range reads. Under normal operation, a transaction will read extra rows from the database into cache if range reads are used to page through a series of data one row at a time (i.e. if a range read with a one row limit is followed by another one row range read starting immediately after the result of the first).

READ_YOUR_WRITES_DISABLE - Reads performed by a transaction will not see any prior mutations that occurred in that transaction, instead seeing the value which was in the database at the transaction’s read version. This option may provide a small performance benefit for the client, but also disables a number of client-side optimizations which are beneficial for transactions which tend to read and write the same keys within a single transaction.

RETRY_LIMIT - Set a maximum number of retries after which additional calls to onError will throw the most recently seen error code. Valid parameter values are [-1, INT_MAX]. If set to -1, will disable the retry limit. Like all transaction options, the retry limit must be reset after a call to onError. This behavior allows the user to make the retry limit dynamic.

TIMEOUT - Set a timeout in milliseconds which, when elapsed, will cause the transaction automatically to be cancelled. Valid parameter values are [0, INT_MAX]. If set to 0, will disable all timeouts. All pending and any future uses of the transaction will throw an exception. The transaction can be used again after it is reset. Like all transaction options, a timeout must be reset after a call to onError. This behavior allows the user to make the timeouts dynamic.


The include command permits previously excluded or failed servers/localities to rejoin the database. Its syntax is include [failed] all|[<ADDRESS...>] [locality_dcid:<excludedcid>] [locality_zoneid:<excludezoneid>] [locality_machineid:<excludemachineid>] [locality_processid:<excludeprocessid>] or any locality.

The failed keyword is required if the servers were previously marked as failed rather than excluded.

If all is specified, the excluded servers and localities list is cleared. This will not clear the failed servers and localities list.

If failed all or all failed is specified, the failed servers and localities list is cleared. This will not clear the excluded servers and localities list.

For each IP address or IP:port pair in <ADDRESS...> or locality, the command removes any matching exclusions from the excluded servers/localities list. (A specified IP will match all IP:* exclusion entries).

For information on adding machines to a cluster, see Adding machines to a cluster.


The kill command attempts to kill one or more processes in the cluster.


With no arguments, kill populates the list of processes that can be killed. This must be run prior to running any other kill commands.

kill list

Displays all known processes. This is only useful when the database is unresponsive.

kill <ADDRESS...>

Attempts to kill all specified processes. Each address should include the IP and port of the process being targeted.

kill all

Attempts to kill all known processes in the cluster.


The listtenants command prints the names of tenants in the cluster. Its syntax is listtenants [BEGIN] [END] [LIMIT].

By default, the listtenants command will print up to 100 entries from the entire range of tenants. A narrower sub-range can be printed using the optional [BEGIN] and [END] parameters, and the limit can be changed by specifying an integer [LIMIT] parameter.


The lock command locks the database with a randomly generated lockUID.


The maintenance command marks a particular zone ID (i.e. fault domain) as being under maintenance. Its syntax is maintenance [on|off] [ZONEID] [SECONDS].

A zone that is under maintenance will not have data moved away from it even if processes in that zone fail. In particular, this means the cluster will not attempt to heal the replication factor as a result of failures in the maintenance zone. This is useful when the amount of time that the processes in a fault domain are expected to be absent is reasonably short and you don’t want to move data to and from the affected processes.

Running this command with no arguments will display the state of any current maintenance.

Running maintenance on <ZONEID> <SECONDS> will turn maintenance on for the specified zone. A duration must be specified for the length of maintenance mode.

Running maintenance off will turn off maintenance mode.


The option command enables or disables an option. Its syntax is option <STATE> <OPTION> [ARG]. Descriptions of the available options can be obtained within fdbcli by typing help options.

If <STATE> is on, then <OPTION> will be enabled with optional parameter <ARG>, if required. If <STATE> is off, then <OPTION> will be disabled.

If there is no active transaction, then the option will be applied to all operations as well as all subsequently created transactions (using begin).

If there is an active transaction (one created with begin), then enabled options apply only to that transaction. Options cannot be disabled on an active transaction.

Calling the option command with no parameters prints a list of all enabled options.


The profile command is used to control various profiling actions.


profile client <get|set>

Reads or sets parameters of client transaction sampling. Use get to list the current parameters, and set <RATE|default> <SIZE|default> to set them. RATE is the fraction of transactions to be sampled, and SIZE is the amount (in bytes) of sampled data to store in the database. For more information, see Transaction profiling and analyzing.


profile list

Lists the processes that can be profiled using the flow and heap subcommands.


profile flow run <DURATION> <FILENAME> <PROCESS...>

Enables flow profiling on the specifed processes for DURATION seconds. Profiling output will be stored at the specified filename relative to the fdbserver process’s trace log directory. To profile all processes, use all for the PROCESS parameter.


profile heap <PROCESS>

Enables heap profiling for the specified process.


The reset command resets the current transaction. Any sets or clears executed after the start of the active transaction will be discarded.


The rollback command rolls back the current transaction. The active transaction will be discarded, including any sets or clears executed since the transaction was started.


The set command sets a value for a given key. Its syntax is set <KEY> <VALUE>. If <KEY> is not already present in the database, it will be created.

Note that characters can be escaped when specifying keys (or values) in fdbcli.


The setclass command can be used to change the process class for a given process. Its syntax is setclass [<ADDRESS> <CLASS>]. If no arguments are specified, then the process classes of all processes are listed. Setting the class to default to revert to the process class specified on the command line.

The available process classes are unset, storage, transaction, resolution, grv_proxy, commit_proxy, master, test, unset, stateless, log, router, cluster_controller, fast_restore, data_distributor, coordinator, ratekeeper, storage_cache, backup, and default.


The sleep command inserts a delay before running the next command. Its syntax is sleep <SECONDS>. This command can be useful when fdbcli is run with the --exec flag to control the timing of commands.


The status command reports the status of the FoundationDB cluster to which fdbcli is connected. Its syntax is status [minimal|details|json].

If the cluster is down, this command will print a diagnostic which may be useful in figuring out what is wrong. If the cluster is running, this command will print cluster statistics.

status minimal

status minimal will provide only an indication of whether the database is available.

status details

status details will provide load information for individual workers.

For a detailed description of status output, see Monitoring cluster status.

status json

status json will provide the cluster status in its JSON format. For a detailed description of this format, see Machine-Readable Status.


The throttle command is used to inspect and modify the list of throttled transaction tags in the cluster. For more information, see Transaction Tagging. The throttle command has the following subcommands:


throttle on tag <TAG> [RATE] [DURATION] [PRIORITY]

Enables throttling for the specified transaction tag.

TAG - the tag being throttled. This argument is required.

RATE - the number of transactions that may be started per second. Defaults to 0.

DURATION - the duration that the throttle should remain in effect, which must include a time suffix (s - seconds, m - minutes, h - hours, d - days). Defaults to 1h.

PRIORITY - the maximum priority that the throttle will apply to. Choices are default, batch, and immediate. Defaults to default.


throttle off [all|auto|manual] [tag <TAG>] [PRIORITY]

Disables throttling for all transaction tag throttles that match the specified filtering criteria. At least one filter must be specified, and filters can be given in any order.

all - affects all throttles (auto and manual).

auto - only throttles automatically created by the cluster will be affected.

manual - only throttles created manually will be affected (this is the default).

tag - only the specified tag will be affected.

PRIORITY - the priority of the throttle to disable. Choices are default, batch, and immediate. Defaults to default.

For example, to disable all throttles, run:

> throttle off all

To disable all manually created batch priority throttles, run:

> throttle off batch

To disable auto throttles at batch priority on the tag foo, run:

> throttle off auto tag foo batch


throttle enable auto

Enables cluster auto-throttling for busy transaction tags.


throttle disable auto

Disables cluster auto-throttling for busy transaction tags. This may not disable currently active throttles immediately, seconds of delay is expected.


throttle list [throttled|recommended|all] [LIMIT]

Prints a list of currently active transaction tag throttles, or recommended transaction tag throttles if auto-throttling is disabled.

throttled - list active transaction tag throttles.

recommended - list transaction tag throttles recommended by the ratekeeper, but not active yet.

all - list both active and recommended transaction tag throttles.

LIMIT - The number of throttles to print. Defaults to 100.


The triggerddteaminfolog command would trigger the data distributor to log very detailed teams information into trace event logs.


The unlock command unlocks the database with the specified lock UID. Because this is a potentially dangerous operation, users must copy a passphrase before the unlock command is executed.


The usetenant command configures fdbcli to run transactions within the specified tenant. Its syntax is usetenant <TENANT_NAME>.

When configured, transactions will read and write keys from the key-space associated with the specified tenant. By default, fdbcli runs without a tenant. Management operations that modify keys (e.g. exclude) will not operate within the tenant.

If the tenant chosen does not exist, fdbcli will report an error.

The active tenant cannot be changed while a transaction (using begin) is open.


Controls whether or not fdbcli can perform sets and clears.

writemode off

Disables writing from fdbcli (the default). In this mode, attempting to set or clear keys will result in an error.

writemode on

Enables writing from fdbcli.


Utility commands for handling quarantining Testing Storage Servers. For more information on this, see Testing Storage Server (TSS).

tssq start <StorageUID>

Manually quarantines a TSS process, if it is not already quarantined.

tssq stop <StorageUID>

Removes a TSS process from quarantine, disposing of the TSS and allowing Data Distribution to recruit a new storage process on the worker.

tssq list:

Lists the storage UIDs of all TSS processes currently in quarantine.