yb-master

Use the yb-master binary and its flags to configure the YB-Master server. The yb-master executable file is located in the bin directory of YugabyteDB home.

Syntax

yb-master [ flag  ] | [ flag ]

Example

./bin/yb-master \
--master_addresses 172.151.17.130:7100,172.151.17.220:7100,172.151.17.140:7100 \
--rpc_bind_addresses 172.151.17.130 \
--fs_data_dirs "/home/centos/disk1,/home/centos/disk2" \
--replication_factor=3

Online help

To display the online help, run yb-master --help from the YugabyteDB home directory:

./bin/yb-master --help

General flags

--version

Shows version and build information, then exits.

--flagfile

Specifies the configuration file to load flags from.

--master_addresses

Specifies a comma-separated list of all RPC addresses for yb-master consensus-configuration.

Note

The number of comma-separated values should match the total number of YB-Master server (or the replication factor).

Required.

Default: 127.0.0.1:7100

--fs_data_dirs

Specifies a comma-separated list of mount directories, where yb-master will add a yb-data/master data directory, master.err, master.out, and pg_data directory.

Required.

Changing the value of this flag after the cluster has already been created is not supported.

--fs_wal_dirs

Specifies a comma-separated list of directories, where yb-master will store write-ahead (WAL) logs. This can be the same as one of the directories listed in --fs_data_dirs, but not a subdirectory of a data directory.

Default: Same value as --fs_data_dirs

--rpc_bind_addresses

Specifies the comma-separated list of the network interface addresses to which to bind for RPC connections.

The values used must match on all yb-master and yb-tserver configurations.

Default: Private IP address of the host on which the server is running, as defined in /home/yugabyte/master/conf/server.conf. For example:

egrep -i rpc /home/yugabyte/master/conf/server.conf
--rpc_bind_addresses=172.161.x.x:7100

Make sure that the server_broadcast_addresses flag is set correctly if the following applies:

  • rpc_bind_addresses is set to 0.0.0.0
  • rpc_bind_addresses involves public IP addresses such as, for example, 0.0.0.0:7100, which instructs the server to listen on all available network interfaces.
--server_broadcast_addresses

Specifies the public IP or DNS hostname of the server (with an optional port). This value is used by servers to communicate with one another, depending on the connection policy parameter.

Default: ""

--dns_cache_expiration_ms

Specifies the duration, in milliseconds, until a cached DNS resolution expires. When hostnames are used instead of IP addresses, a DNS resolver must be queried to match hostnames to IP addresses. By using a local DNS cache to temporarily store DNS lookups, DNS queries can be resolved quicker and additional queries can be avoided. This reduces latency, improves load times, and reduces bandwidth and CPU consumption.

Default: 60000 (1 minute)

Note

If this value is changed from the default, make sure to add the same value to all YB-Master and YB-TSever configurations.
--use_private_ip

Specifies the policy that determines when to use private IP addresses for inter-node communication. Possible values are never, zone, cloud, and region. Based on the values of the geo-distribution flags.

Valid values for the policy are:

Default: never

--webserver_interface

Specifies the bind address for web server user interface access.

Default: 0.0.0.0

--webserver_port

Specifies the web server monitoring port.

Default: 7000

--webserver_doc_root

Monitoring web server home.

Default: The www directory in the YugabyteDB home directory.

--webserver_certificate_file

Location of the SSL certificate file (in .pem format) to use for the web server. If empty, SSL is not enabled for the web server.

Default: ""

--webserver_authentication_domain

Domain used for .htpasswd authentication. This should be used in conjunction with --webserver_password_file.

Default: ""

--webserver_password_file

Location of .htpasswd file containing usernames and hashed passwords, for authentication to the web server.

Default: ""

--defer_index_backfill

If enabled, yb-master avoids launching any new index-backfill jobs on the cluster for all new YCQL indexes. You will need to run yb-admin backfill_indexes_for_table manually for indexes to be functional. See CREATE DEFERRED INDEX for reference.

Default: false

--allow_batching_non_deferred_indexes

If enabled, indexes on the same (YCQL) table may be batched together during backfill, even if they were not deferred.

Default: true

YSQL flags

--enable_ysql

Note

Ensure that enable_ysql values in yb-master configurations match the values in yb-tserver configurations.

Enables the YSQL API when value is true.

Default: true

Logging flags

--colorlogtostderr

Color messages logged to stderr (if supported by terminal).

Default: false

--logbuflevel

Buffer log messages logged at this level (or lower).

Valid values: -1 (don't buffer); 0 (INFO); 1 (WARN); 2 (ERROR); 3 (FATAL)

Default: 0

--logbufsecs

Buffer log messages for at most this many seconds.

Default: 30

--logtostderr

Write log messages to stderr instead of logfiles.

Default: false

--log_dir

The directory to write yb-master log files.

Default: Same as --fs_data_dirs

Put additional links to the log files in this directory.

Default: ""

--log_prefix

Prepend the log prefix to each log line.

Default: true

--max_log_size

The maximum log size, in megabytes (MB). A value of 0 will be silently overridden to 1.

Default: 1800 (1.8 GB)

--minloglevel

The minimum level to log messages. Values are: 0 (INFO), 1 (WARN), 2 (ERROR), 3 (FATAL).

Default: 0 (INFO)

--stderrthreshold

Log messages at, or above, this level are copied to stderr in addition to log files.

Default: 2

--callhome_enabled

Disable callhome diagnostics.

Default: true

Memory division flags

These flags are used to determine how the RAM of a node is split between the master process and other processes, including Postgres and a TServer process if present, as well as how to split memory inside of a master process between various internal components like the RocksDB block cache.

Warning

Ensure you do not oversubscribe memory when changing these flags: make sure the amount of memory reserved for the master process and TServer if present leaves enough memory on the node for Postgres, and any required other processes like monitoring agents plus the memory needed by the kernel.

Flags controlling the defaults for the other memory division flags

The memory division flags have multiple sets of defaults; which set of defaults is in force depends on these flags. Note that these defaults can differ between TServer and master.

--use_memory_defaults_optimized_for_ysql

If true, the defaults for the memory division settings take into account the amount of RAM and cores available and are optimized for using YSQL. If false, the defaults will be the old defaults, which are more suitable for YCQL but do not take into account the amount of RAM and cores available.

Default: false

If this flag is true then the memory division flag defaults change to provide much more memory for Postgres; furthermore, they optimize for the node size.

If these defaults are used for both TServer and master, then a node's available memory is partitioned as follows:

node RAM GiB (M): M  ≤  4 4 < M  ≤  8 8 < M  ≤  16 16 < M
TServer % 45% 48% 57% 60%
master % 20% 15% 10% 10%
Postgres % 25% 27% 28% 27%
other % 10% 10% 5% 3%

To read this table, take your node's available memory in GiB, call it M, and find the column who's heading condition M meets. For example, a node with 7 GiB of available memory would fall under the column labeled "4 < M ≤ 8" because 4 < 7 ≤ 8. The defaults for --default_memory_limit_to_ram_ratio on this node will thus be 0.48 for TServers and 0.15 for masters. The Postgres and other percentages are not set via a flag currently but rather consist of whatever memory is left after TServer and master take their cut. There is currently no distinction between Postgres and other memory except on YugabyteDB Managed where a cgroup is used to limit the Postgres memory.

For comparison, when --use_memory_defaults_optimized_for_ysql is false, the split is TServer 85%, master 10%, Postgres 0%, and other 5%.

The defaults for the master process partitioning flags when --use_memory_defaults_optimized_for_ysql is true do not depend on the node size, and are described in the following table:

flag default
--db_block_cache_size_percentage 25
--tablet_overhead_size_percentage 0

Currently these are the same as the defaults when --use_memory_defaults_optimized_for_ysql is false, but may change in future releases.

Given the amount of RAM devoted to per tablet overhead, it is possible to compute the maximum number of tablet replicas (see allowing for tablet replica overheads); following are some sample values for selected node sizes using --use_memory_defaults_optimized_for_ysql:

total node GiB max number of tablet replicas max number of Postgres connections
4 240 30
8 530 65
16 1,250 130
32 2,700 225
64 5,500 370
128 11,000 550
256 22,100 730

These values are approximate because different kernels use different amounts of memory, leaving different amounts of memory for the TServer and thus the per-tablet overhead TServer component.

Also shown is an estimate of how many Postgres connections that node can handle assuming default Postgres flags and usage. Unusually memory expensive queries or preloading Postgres catalog information will reduce the number of connections that can be supported.

Thus a 8 GiB node would be expected to be able support 530 tablet replicas and 65 (physical) typical Postgres connections. A universe of six of these nodes would be able to support 530 * 2 = 1,060 RF3 tablets and 65 * 6 = 570 typical physical Postgres connections assuming the connections are evenly distributed among the nodes.

Flags controlling the split of memory among processes

Note that in general these flags will have different values for TServer and master processes.

--memory_limit_hard_bytes

Maximum amount of memory this process should use in bytes, that is, its hard memory limit. A value of 0 specifies to instead use a percentage of the total system memory; see --default_memory_limit_to_ram_ratio for the percentage used. A value of -1 disables all memory limiting.

Default: 0

--default_memory_limit_to_ram_ratio

The percentage of available RAM to use for this process if --memory_limit_hard_bytes is 0. The special value -1000 means to instead use the default value for this flag. Available RAM excludes memory reserved by the kernel.

Default: 0.10 unless --use_memory_defaults_optimized_for_ysql is true.

Flags controlling the split of memory within a master process

--db_block_cache_size_bytes

Size of the shared RocksDB block cache (in bytes). A value of -1 specifies to instead use a percentage of this processes' hard memory limit; see --db_block_cache_size_percentage for the percentage used. A value of -2 disables the block cache.

Default: -1

--db_block_cache_size_percentage

Percentage of the process' hard memory limit to use for the shared RocksDB block cache if --db_block_cache_size_bytes is -1. The special value -1000 means to instead use the default value for this flag. The special value -3 means to use an older default that does not take the amount of RAM into account.

Default: 25 unless --use_memory_defaults_optimized_for_ysql is true.

--tablet_overhead_size_percentage

Percentage of the process' hard memory limit to use for tablet-related overheads. A value of 0 means no limit. Must be between 0 and 100 inclusive. Exception: -1000 specifies to instead use the default value for this flag.

Each tablet replica generally requires 700 MiB of this memory.

Default: 0 unless --use_memory_defaults_optimized_for_ysql is true.

Raft flags

For a typical deployment, values used for Raft and the write ahead log (WAL) flags in yb-master configurations should match the values in yb-tserver configurations.

--follower_unavailable_considered_failed_sec

The duration, in seconds, after which a follower is considered to be failed because the leader has not received a heartbeat.

Default: 7200 (2 hours)

The --follower_unavailable_considered_failed_sec value should match the value for --log_min_seconds_to_retain.

--evict_failed_followers

Failed followers will be evicted from the Raft group and the data will be re-replicated.

Default: false

Note that it is not recommended to set the flag to true for masters as you cannot automatically recover a failed master once it is evicted.

--leader_failure_max_missed_heartbeat_periods

The maximum heartbeat periods that the leader can fail to heartbeat in before the leader is considered to be failed. The total failure timeout, in milliseconds, is --raft_heartbeat_interval_ms multiplied by --leader_failure_max_missed_heartbeat_periods.

For read replica clusters, set the value to 10 in all yb-tserver and yb-master configurations. Because the data is globally replicated, RPC latencies are higher. Use this flag to increase the failure detection interval in such a higher RPC latency deployment.

Default: 6

--leader_lease_duration_ms

The leader lease duration, in milliseconds. A leader keeps establishing a new lease or extending the existing one with every consensus update. A new server is not allowed to serve as a leader (that is, serve up-to-date read requests or acknowledge write requests) until a lease of this duration has definitely expired on the old leader's side, or the old leader has explicitly acknowledged the new leader's lease.

This lease allows the leader to safely serve reads for the duration of its lease, even during a network partition. For more information, refer to Leader leases.

Leader lease duration should be longer than the heartbeat interval, and less than the multiple of --leader_failure_max_missed_heartbeat_periods multiplied by --raft_heartbeat_interval_ms.

Default: 2000

--raft_heartbeat_interval_ms

The heartbeat interval, in milliseconds, for Raft replication. The leader produces heartbeats to followers at this interval. The followers expect a heartbeat at this interval and consider a leader to have failed if it misses several in a row.

Default: 500

Write ahead log (WAL) flags

Ensure that values used for the write ahead log (WAL) in yb-master configurations match the values in yb-tserver configurations.

--fs_wal_dirs

The directory where the yb-tserver retains WAL files. May be the same as one of the directories listed in --fs_data_dirs, but not a subdirectory of a data directory.

Default: Same as --fs_data_dirs

--durable_wal_write

If set to false, the writes to the WAL are synced to disk every interval_durable_wal_write_ms milliseconds (ms) or every bytes_durable_wal_write_mb megabyte (MB), whichever comes first. This default setting is recommended only for multi-AZ or multi-region deployments where the availability zones (AZs) or regions are independent failure domains and there is not a risk of correlated power loss. For single AZ deployments, this flag should be set to true.

Default: false

--interval_durable_wal_write_ms

When --durable_wal_write is false, writes to the WAL are synced to disk every --interval_durable_wal_write_ms or --bytes_durable_wal_write_mb, whichever comes first.

Default: 1000

--bytes_durable_wal_write_mb

When --durable_wal_write is false, writes to the WAL are synced to disk every --bytes_durable_wal_write_mb or --interval_durable_wal_write_ms, whichever comes first.

Default: 1

--log_min_seconds_to_retain

The minimum duration, in seconds, to retain WAL segments, regardless of durability requirements. WAL segments can be retained for a longer amount of time, if they are necessary for correct restart. This value should be set long enough such that a tablet server which has temporarily failed can be restarted in the given time period.

Default: 7200 (2 hours)

The --log_min_seconds_to_retain value should match the value for --follower_unavailable_considered_failed_sec.

--log_min_segments_to_retain

The minimum number of WAL segments (files) to retain, regardless of durability requirements. The value must be at least 1.

Default: 2

--log_segment_size_mb

The size, in megabytes (MB), of a WAL segment (file). When the WAL segment reaches the specified size, then a log rollover occurs and a new WAL segment file is created.

Default: 64

--reuse_unclosed_segment_threshold_bytes

When the server restarts from a previous crash, if the tablet's last WAL file size is less than or equal to this threshold value, the last WAL file will be reused. Otherwise, WAL will allocate a new file at bootstrap. To disable WAL reuse, set the value to -1.

Default: The default value in 2.18.1 is -1 - feature is disabled by default. The default value starting from 2.19.1 is 524288 (0.5 MB) - feature is enabled by default.

Load balancing flags

For information on YB-Master load balancing, see Tablet assignments.

For load balancing commands in yb-admin, see Rebalancing commands (yb-admin).

--enable_load_balancing

Enables or disables the load balancing algorithm, to move tablets around.

Default: true

--leader_balance_threshold

Specifies the number of leaders per tablet server to balance below. If this is configured to 0 (the default), the leaders will be balanced optimally at extra cost.

Default: 0

--leader_balance_unresponsive_timeout_ms

Specifies the period of time, in milliseconds, that a YB-Master can go without receiving a heartbeat from a YB-TServer before considering it unresponsive. Unresponsive servers are excluded from leader balancing.

Default: 3000 (3 seconds)

--load_balancer_max_concurrent_adds

Specifies the maximum number of tablet peer replicas to add in a load balancer operations.

Default: 1

--load_balancer_max_concurrent_moves

Specifies the maximum number of tablet leaders on tablet servers (across the cluster) to move in a load balancer operation.

Default: 2

--load_balancer_max_concurrent_moves_per_table

Specifies the maximum number of tablet leaders per table to move in any one run of the load balancer. The maximum number of tablet leader moves across the cluster is still limited by the flag load_balancer_max_concurrent_moves. This flag is meant to prevent a single table from using all of the leader moves quota and starving other tables.

Default: 1

--load_balancer_max_concurrent_removals

Specifies the maximum number of over-replicated tablet peer removals to do in a load balancer operation.

Default: 1

--load_balancer_max_concurrent_tablet_remote_bootstraps

Specifies the maximum number of tablets being remote bootstrapped across the cluster.

Default: 10

--load_balancer_max_concurrent_tablet_remote_bootstraps_per_table

Maximum number of tablets being remote bootstrapped for any table. The maximum number of remote bootstraps across the cluster is still limited by the flag load_balancer_max_concurrent_tablet_remote_bootstraps. This flag is meant to prevent a single table use all the available remote bootstrap sessions and starving other tables.

Default: 2

--load_balancer_max_over_replicated_tablets

Specifies the maximum number of running tablet replicas that are allowed to be over the configured replication factor.

Default: 1

--load_balancer_num_idle_runs

Specifies the number of idle runs of load balancer to deem it idle.

Default: 5

--load_balancer_skip_leader_as_remove_victim

Should the LB skip a leader as a possible remove candidate.

Default: false

Sharding flags

--max_clock_skew_usec

The expected maximum clock skew, in microseconds (µs), between any two servers in your deployment.

Default: 500000 (500,000 µs = 500ms)

--replication_factor

The number of replicas, or copies of data, to store for each tablet in the universe.

Default: 3

--yb_num_shards_per_tserver

The number of shards (tablets) per YB-TServer for each YCQL table when a user table is created.

Default: -1, where the number of shards is determined at runtime, as follows:

  • If enable_automatic_tablet_splitting is true

    • The default value is considered as 1.
    • For servers with 4 CPU cores or less, the number of tablets for each table doesn't depend on the number of YB-TServers. Instead, for 2 CPU cores or less, 1 tablet per cluster is created; for 4 CPU cores or less, 2 tablets per cluster are created.
  • If enable_automatic_tablet_splitting is false

    • For servers with up to two CPU cores, the default value is considered as 4.
    • For three or more CPU cores, the default value is considered as 8.

Local cluster installations created using yb-ctl and yb-docker-ctl use a default value of 2 for this flag.

Clusters created using yugabyted always use a default value of 1.

Note

  • This value must match on all yb-master and yb-tserver configurations of a YugabyteDB cluster.
  • If the value is set to Default (-1), then the system automatically determines an appropriate value based on the number of CPU cores and internally updates the flag with the intended value during startup prior to version 2.18 and the flag remains unchanged starting from version 2.18.
  • The CREATE TABLE ... WITH TABLETS = <num> clause can be used on a per-table basis to override the yb_num_shards_per_tserver value.
--ysql_num_shards_per_tserver

The number of shards (tablets) per YB-TServer for each YSQL table when a user table is created.

Default: -1, where the number of shards is determined at runtime, as follows:

  • If enable_automatic_tablet_splitting is true

    • The default value is considered as 1.
    • For servers with 4 CPU cores or less, the number of tablets for each table doesn't depend on the number of YB-TServers. Instead, for 2 CPU cores or less, 1 tablet per cluster is created; for 4 CPU cores or less, 2 tablets per cluster are created.
  • If enable_automatic_tablet_splitting is false

    • For servers with up to two CPU cores, the default value is considered as 2.
    • For servers with three or four CPU cores, the default value is considered as 4.
    • Beyond four cores, the default value is considered as 8.

Local cluster installations created using yb-ctl and yb-docker-ctl use a default value of 2 for this flag.

Clusters created using yugabyted always use a default value of 1.

Note

  • This value must match on all yb-master and yb-tserver configurations of a YugabyteDB cluster.
  • If the value is set to Default (-1), the system automatically determines an appropriate value based on the number of CPU cores and internally updates the flag with the intended value during startup prior to version 2.18 and the flag remains unchanged starting from version 2.18.
  • The CREATE TABLE ...SPLIT INTO clause can be used on a per-table basis to override the ysql_num_shards_per_tserver value.
--ysql_colocate_database_by_default

When enabled, all databases created in the cluster are colocated by default. If you enable the flag after creating a cluster, you need to restart the YB-Master and YB-TServer services.

For more details, see clusters in colocated tables.

Default: false

Tablet splitting flags

--enable_automatic_tablet_splitting

Enables YugabyteDB to automatically split tablets, based on the specified tablet threshold sizes configured below.

Default: true

Important

This value must match on all yb-master and yb-tserver configurations of a YugabyteDB cluster.
--tablet_split_low_phase_shard_count_per_node

The threshold number of shards (per cluster node) in a table below which automatic tablet splitting will use --tablet_split_low_phase_size_threshold_bytes to determine which tablets to split.

Default: 1

--tablet_split_low_phase_size_threshold_bytes

The size threshold used to determine if a tablet should be split when the tablet's table is in the "low" phase of automatic tablet splitting. See --tablet_split_low_phase_shard_count_per_node.

Default: 128_MB

--tablet_split_high_phase_shard_count_per_node

The threshold number of shards (per cluster node) in a table below which automatic tablet splitting will use --tablet_split_high_phase_size_threshold_bytes to determine which tablets to split.

Default: 24

--tablet_split_high_phase_size_threshold_bytes

The size threshold used to determine if a tablet should be split when the tablet's table is in the "high" phase of automatic tablet splitting. See --tablet_split_high_phase_shard_count_per_node.

Default: 10_GB

--tablet_force_split_threshold_bytes

The size threshold used to determine if a tablet should be split even if the table's number of shards puts it past the "high phase".

Default: 100_GB

--tablet_split_limit_per_table

The maximum number of tablets per table for tablet splitting. Limitation is disabled if this value is set to 0.

Default: 256

--index_backfill_tablet_split_completion_timeout_sec

Total time to wait for tablet splitting to complete on a table on which a backfill is running before aborting the backfill and marking it as failed.

Default: 30

--index_backfill_tablet_split_completion_poll_freq_ms

Delay before retrying to see if tablet splitting has completed on the table on which a backfill is running.

Default: 2000

--process_split_tablet_candidates_interval_msec

The minimum time between automatic splitting attempts. The actual splitting time between runs is also affected by catalog_manager_bg_task_wait_ms, which controls how long the background tasks thread sleeps at the end of each loop.

Default: 0

--outstanding_tablet_split_limit

Limits the number of total outstanding tablet splits. Limitation is disabled if value is set to 0. Limit includes tablets that are performing post-split compactions.

Default: 0

--outstanding_tablet_split_limit_per_tserver

Limits the number of outstanding tablet splits per node. Limitation is disabled if value is set to 0. Limit includes tablets that are performing post-split compactions.

Default: 1

--enable_tablet_split_of_pitr_tables

Enables automatic tablet splitting of tables covered by Point In Time Recovery schedules.

Default: true

--prevent_split_for_ttl_tables_for_seconds

Number of seconds between checks for whether to split a tablet with a default TTL. Checks are disabled if this value is set to 0.

Default: 86400

--prevent_split_for_small_key_range_tablets_for_seconds

Number of seconds between checks for whether to split a tablet whose key range is too small to be split. Checks are disabled if this value is set to 0.

Default: 300

--sort_automatic_tablet_splitting_candidates

Determines whether to sort automatic split candidates from largest to smallest (prioritizing larger tablets for split).

Default: true

Syntax:

yb-admin --master_addresses <master-addresses> --tablet_force_split_size_threshold_bytes <bytes>
  • master-addresses: Comma-separated list of YB-Master hosts and ports. Default value is localhost:7100.
  • bytes: The threshold size, in bytes, after which tablets should be split. Default value of 0 disables automatic tablet splitting.

For details on automatic tablet splitting, see the following:

Geo-distribution flags

Settings related to managing geo-distributed clusters.

--placement_zone

The name of the availability zone (AZ), or rack, where this instance is deployed.

Default: rack1

--placement_region

Name of the region or data center where this instance is deployed.

Default: datacenter1

--placement_cloud

Name of the cloud where this instance is deployed.

Default: cloud1

--placement_uuid

The unique identifier for the cluster.

Default: ""

-- use_private_ip

Determines when to use private IP addresses. Possible values are never (default),zone,cloud and region. Based on the values of the placement_* configuration flags.

Default: never

--auto_create_local_transaction_tables

If true, transaction tables will be automatically created for any YSQL tablespace which has a placement and at least one other table in it.

Default: true

Security flags

For details on enabling server-to-server encryption, see Server-server encryption.

--certs_dir

Directory that contains certificate authority, private key, and certificates for this server.

Default: "" (uses <data drive>/yb-data/master/data/certs.)

--allow_insecure_connections

Allow insecure connections. Set to false to prevent any process with unencrypted communication from joining a cluster. Note that this flag requires the use_node_to_node_encryption to be enabled.

Default: true

--dump_certificate_entries

Adds certificate entries, including IP addresses and hostnames, to log for handshake error messages. Enabling this flag is helpful for debugging certificate issues.

Default: false

--use_node_to_node_encryption

Enables server-server or node-to-node encryption between YB-Master and YB-TServer servers in a cluster or universe. To work properly, all YB-Master servers must also have their --use_node_to_node_encryption flag enabled. When enabled, then --allow_insecure_connections flag must be disabled.

Default: false

--cipher_list

Specify cipher lists for TLS 1.2 and earlier versions. (For TLS 1.3, use --ciphersuite.) Use a colon-separated list of TLS 1.2 cipher names in order of preference. Use an exclamation mark ( ! ) to exclude ciphers. For example:

--cipher_list DEFAULTS:!DES:!IDEA:!3DES:!RC2

This allows all ciphers for TLS 1.2 to be accepted, except those matching the category of ciphers omitted.

This flag requires a restart or rolling restart.

Default: DEFAULTS

For more information, refer to SSL_CTX_set_cipher_list in the OpenSSL documentation.

--ciphersuite

Specify cipher lists for TLS 1.3. For TLS 1.2 and earlier, use --cipher_list.

Use a colon-separated list of TLS 1.3 ciphersuite names in order of preference. Use an exclamation mark ( ! ) to exclude ciphers. For example:

--ciphersuite DEFAULTS:!CHACHA20

This allows all ciphersuites for TLS 1.3 to be accepted, except CHACHA20 ciphers.

This flag requires a restart or rolling restart.

Default: DEFAULTS

For more information, refer to SSL_CTX_set_cipher_list in the OpenSSL documentation.

Change data capture (CDC) flags

To learn about CDC, see Change data capture (CDC).

For information on other CDC configuration flags, see YB-TServer's CDC flags.

--cdc_state_table_num_tablets

The number of tablets to use when creating the CDC state table. Used in both xCluster and CDCSDK.

Default: 0 (Use the same default number of tablets as for regular tables.)

--cdc_wal_retention_time_secs

WAL retention time, in seconds, to be used for tables for which a CDC stream was created. Used in both xCluster and CDCSDK.

Default: 14400 (4 hours)

--enable_tablet_split_of_cdcsdk_streamed_tables

Toggle automatic tablet splitting for tables in a CDCSDK stream, enhancing user control over replication processes.

Default: false

Metric export flags

--export_help_and_type_in_prometheus_metrics

YB-Master metrics are available in Prometheus format at http://localhost:7000/prometheus-metrics. This flag controls whether #TYPE and #HELP information is included as part of the Prometheus metrics output by default.

To override this flag on a per-scrape basis, set the URL parameter show_help to true to include or to false to not include type and help information. For example, querying http://localhost:7000/prometheus-metrics?show_help=true will return type and help information regardless of the setting of this flag.

Default: true

Catalog flags

ysql_enable_db_catalog_version_mode

Enable the per database catalog version mode. A DDL statement that affects the current database can only increment catalog version for that database.

Default: true

Important

Previously, after a DDL statement is executed, if the DDL statement increments the catalog version, then all the existing connections need to refresh catalog caches before they execute the next statement. When per database catalog version mode is enabled, multiple DDL statements can be concurrently executed if each DDL only affects its current database and is executed in a separate database. Existing connections only need to refresh their catalog caches if they are connected to the same database as that of a DDL statement. It is recommended to keep the default value of this flag because per database catalog version mode helps to avoid unnecessary cross-database catalog cache refresh which is considered as an expensive operation.

If you encounter any issues caused by per database catalog version mode, you can disable per database catalog version mode using the following steps:

  1. Shut down the cluster.

  2. Start the cluster with --ysql_enable_db_catalog_version_mode=false.

  3. Execute the following YSQL statements:

    SET yb_non_ddl_txn_for_sys_tables_allowed=true;
    SELECT yb_fix_catalog_version_table(false);
    SET yb_non_ddl_txn_for_sys_tables_allowed=false;
    

To re-enable the per database catalog version mode, use the following steps:

  1. Execute the following YSQL statements:

    SET yb_non_ddl_txn_for_sys_tables_allowed=true;
    SELECT yb_fix_catalog_version_table(true);
    SET yb_non_ddl_txn_for_sys_tables_allowed=false;
    
  2. Shut down the cluster.

  3. Start the cluster with --ysql_enable_db_catalog_version_mode=true.

enable_heartbeat_pg_catalog_versions_cache

Whether to enable the use of heartbeat catalog versions cache for the pg_yb_catalog_version table which can help to reduce the number of reads from the table. This is beneficial when there are many databases and/or many yb-tservers in the cluster.

Note that enable_heartbeat_pg_catalog_versions_cache is only used when ysql_enable_db_catalog_version_mode is true.

Default: false

Important

Each yb-tserver regularly sends a heartbeat request to the yb-master leader. As part of the heartbeat response, yb-master leader reads all the rows in the table pg_yb_catalog_version and sends the result back in the heartbeat response. As there is one row in the table pg_yb_catalog_version for each database, the cost of reading table pg_yb_catalog_version becomes more expensive when the number of yb-tservers, or the number of databases goes up.

Advanced flags

ysql_index_backfill_rpc_timeout_ms

Deadline (in milliseconds) for each internal YB-Master to YB-TServer RPC for backfilling a chunk of the index.

Default: 60000 (1 minute)

hide_dead_node_threshold_mins

After this many minutes of no heartbeat from a node, hide it from the UI (we presume it has been removed from the cluster). If -1, this flag is ignored and the node is never hidden from the UI

Default: 1440 (1 day)

Admin UI

The Admin UI for YB-Master is available at http://localhost:7000.

Home

Home page of the YB-Master server that gives a high level overview of the cluster. Not all YB-Master servers in a cluster show identical information.

master-home

Namespaces

List of namespaces present in the cluster.

master-namespaces

Tables

List of tables present in the cluster.

master-tables

Tablet servers

List of all nodes (aka YB-TServer servers) present in the cluster.

master-tservers

Debug

List of all utilities available to debug the performance of the cluster.

master-debug