obcdc parameters|V4.3.3| docs|Distributed Database

Note that for parameters of the Boolean type in the following table, the value 0 indicates False and the value 1 indicates True.

Cluster parameters

Metadata parameters

Parameter	Description	Default value	Real-time modification supported	Remarks
init_log_level	The initial log level at startup.	ALL.*:INFO;SHARE.SCHEMA:INFO	No	The initial log level is used to generate more detailed logs. The log level is changed to the specified log_level after startup.
log_level	The log level after startup.	ALL.*:INFO;SHARE.SCHEMA:WARN	Yes	/
max_log_file_count	The maximum number of log files.	0	No	The value must be greater than or equal to 0. If the value is 0, the number of logs is not restricted. If you change the value to a smaller one, restart OceanBase Change Data Capture (obcdc) for the configuration to take effect.
enable_log_limit	Specifies whether to enable log throttling.	1	Yes	The value `1` specifies to enable log throttling. The value `0` specifies to disable log throttling.
rootserver_list	The RootService server specified at startup.	`\\|`	Yes	The information about each server must be in the format of `server_ip:server_rpc_port:server_sql_port`.
cluster_url	The cluster URL specified at startup.	`\\|`	No	If OceanBase Database has a cluster URL, obcdc uses this URL to obtain the RootServer information. High availability is supported for servers.
cluster_user	The username in the sys tenant.	Empty (required, to be specified by the user)	No	Specify a user in the sys tenant. This user must have the read privilege on internal tables.
cluster_password	The password of the preceding user.	Empty (required, to be specified by the user)	No	/
cluster_db_name	The name of the database where the internal tables that obcdc queries reside.	oceanbase	No	You do not need to modify the value. By default, internal tables are in the oceanbase database.
tenant_endpoint	The list of servers where the tenant resides.	`\\|`	No	The information about each server must be in the format of `host:sql_port`. Separate the information about different servers with vertical bars (`\\|`).
tenant_user	The name of a user in the tenant.	`\\|`	No	The format is `user_name@tenant_name` or `user_name@tenant_name#cluster`.
tenant_password	The password of the preceding user in the tenant.	`\\|`	No	/
config_fpath	The dump path of the configuration file.	etc/liboblog.conf	No	All obcdc configuration information will be dumped into this file.
timezone	The time zone of obcdc.	+8:00	No	This parameter specifies the time zone in which data is formatted and exported, which must be consistent with that of the data source. The default time zone is UTC+8.
timezone_info_path	The directory where the timezone metadata file is located.	etc/timezone_info.conf	Yes	When `meta_data_refresh_mode` is set to `data_dict`, the `timezone_info.conf` file in the RPM package must be placed in this directory.
skip_ob_version_compat_check	Specifies whether to skip the OceanBase version compatibility check.	0	No	obcdc V3.x supports data synchronization with only OceanBase Database V2.x and V3.x. In addition, the obcdc version must be later than the OceanBase Database version.
cluster_version_refresh_interval_sec	The interval for querying the earliest OBServer node version of the OceanBase cluster.	600	No	This parameter specifies the interval for refreshing the OceanBase cluster version, in seconds.
log_router_background_refresh_interval_sec	The frequency for refreshing the log stream metadata.	10	Yes	This parameter specifies the interval, in seconds, for refreshing the corresponding server information at the backend for the log stream.

Parameter	Description	Default value	Real-time modification supported	Remarks
working_mode	The working mode.	storage (commercial edition)	No	The transaction size must be controlled in business scenarios. If large transactions exist in business scenarios, use the persistence mode. We recommend that you deploy obcdc on the SSD in persistence mode.
store_service_path	The path for storing data in persistence mode.	./storage	No	This parameter is valid only in persistence mode. Relative path: The persistent data is stored in a relative path in the path of the process that calls obcdc. Absolute path: The persistent data is stored in the specified absolute path, such as `store_service_path=/data/1`.

Synchronization granularity

obcdc supports data synchronization in multiple dimensions. A single obcdc instance can synchronize the data of one cluster, one or more tenants, several databases, and several tables.

Synchronization granularity	Single obcdc instance	Multiple obcdc instances
Cluster	Supported (A single obcdc instance does not support the data of multiple clusters.)	Supported
Tenant	Supported	Supported
Database	Not supported	Not supported
Table	Not supported	Not supported (For more information, see the following multi-instance-related parameters.)

If the traffic in the tenant is heavy, a single obcdc instance may fail to synchronize the data of the entire cluster in real time. In this case, you can use multiple obcdc instances to share the load, with each instance synchronizing the data of a different tenant.

Parameter	Description	Default value	Real-time modification supported	Remarks
enable_white_black_list	Specifies whether to enable the allowlist and blocklist feature in obcdc.	1	No	By default, the allowlist and blocklist feature is enabled, with the allowlist and blocklist parameters being effective. If you disable the allowlist and blocklist feature, all data of the tenants included in the allowlist is synchronized.
tb_white_list	The allowlist of the tables to be synchronized.	..*	No	The information about each table must be in the format of `tenant name.database name.table name`, for example, `mytenant1.db1.tb1\\|mytenant2.db2.\*`.
tb_black_list	The blocklist of tables not to be synchronized.	`\\|`	No	The format is the same as above.
tablegroup_white_list	The allowlist of table groups to be synchronized.	.	No	The information about each table group must be in the format of `tenant name.table group name`, for example, `mytenant1.\\\|or_tenant\.tg\*`.
tablegroup_black_list	The blocklist of table groups not to be synchronized	`\\|`	No	The format is the same as above.
enable_filter_sys_tenant	Specifies whether to filter synchronization data of the sys tenant.	0	No	Enable this option when the sys tenant is abnormal but the user tenants are normal.

Note

obcdc provides data filtering capabilities based on table and table group allowlists and blocklists.

Only the tables and table groups in the allowlist but not in the blocklist will be synchronized. By default, all tables and table groups in all tenants are in the allowlist, and the blocklist is empty. We recommend that you configure an allowlist for the production environment to synchronize data of specified tenants. Do not use the default values, which may pull redundant data.
The fnmatch function is used to match tables and table groups based on regular expressions. By default, case sensitivity is disabled for matching tables and table groups. You can set `enable_oracle_mode_match_case_sensitive` to `1` to enable case sensitivity for tenants in Oracle mode.

Parameter	Description	Default value	Real-time modification supported	Remarks
instance_num	The total number of obcdc instances.	1	No	/
instance_index	The index of the current obcdc instance to the total number of obcdc instances (which can be understood as the hash bucket ID).	0	No	The value range is [0, instance_num). Each obcdc instance processes only the data of the log streams that match the following formula: `hash(tenant_id, ls_id) % instance_num = instance_index`.
enable_global_unique_index_belong_to_multi_instance	Specifies whether to synchronize tables with globally unique indexes in multi-instance scenarios.	0	Yes	The value `0` specifies not to synchronize tables with globally unique indexes in multi-instance scenarios.

Throttling

To prevent out-of-memory (OOM) issues caused by data heaping in the memory in the case of exceptions, obcdc provides throttling capabilities. Throttling is triggered based on the internal status of obcdc. Data pulling stops during throttling and resumes when obcdc becomes normal. The following table describes the throttling control parameters. You can modify them to adjust the throttling level as needed.

Parameter	Description	Default value	Real-time modification supported	Remarks
memory_limit	The memory limit for triggering throttling.	`20G`	Yes	It is one of the throttling metrics. obcdc tries to keep the memory usage within the specified value of `memory_limit`. However, it does not restrict obcdc from using memory higher than `memory_limit`. The minimum value is `2G`.
memory_usage_warn_threshold	The ratio of the memory usage to the value of the `memory_limit` parameter for triggering log pull throttling.	85	Yes	/
system_memory_avail_percentage_lower_bound	The lower limit of available system memory, in percentage.	10	Yes	The value range is [10, 80].
part_trans_task_active_count_upper_bound	The maximum number of active partition transactions.	200000	Yes	This parameter specifies the number of active partition transaction structs in memory (allocated and not recycled).
storager_task_count_upper_bound	The throttling threshold of the number of tasks for storager to persist.	1000	Yes	The minimum value is `1`.
storager_mem_percentage	The percentage of memory used by the persistence module in the throttling memory.	1	Yes	The value `0` specifies automatic adjustment.
part_trans_task_reusable_count_upper_bound	The maximum number of partition transactions to reuse.	10240	Yes	This parameter specifies the sum of tasks to be generated to the user queue, tasks to be generated by users, tasks to be returned by users, and tasks pending for garbage collection (GC).
ready_to_seq_task_upper_bound	The maximum number of tasks to be sequenced.	2000	Yes	This parameter specifies the maximum number of tasks to be sequenced, including tasks pending for parsing, tasks pending for formatting, and tasks pending for persistence.
pause_fetcher	Specifies whether to forcibly stop pulling logs.	0	Yes	The value `0` specifies to forcibly stop pulling logs regardless of the logical computing result of the throttling conditions.
direct_load_inc_thread_num	The number of threads for reading and parsing incremental direct load logs.	0	Yes	This is a parameter used to limit memory usage. Its value can be automatically adapted based on the `memory_limit` parameter of obcdc or be manually modified for dynamic adjustment. Notice If you enable the incremental direct load feature and use obcdc for data synchronization, proceed with caution when adjusting this parameter. Otherwise, the memory usage limit may be exceeded.
direct_load_inc_queue_backlog_lowest_tolerance	The task backlog threshold for triggering throttling.	0	Yes	This is a parameter used to limit memory usage. Its value can be automatically adapted based on the `memory_limit` parameter of obcdc or be manually modified for dynamic adjustment. Notice If you enable the incremental direct load feature and use obcdc for data synchronization, proceed with caution when adjusting this parameter. Otherwise, the memory usage limit may be exceeded.

The reference throttling conditions are as follows:

Condition 1: The number of active partitions exceeds the threshold specified by part_trans_task_active_count_upper_bound. || The memory held by obcdc exceeds the threshold specified by memory_limit. || The available memory of the system is lower than the threshold specified by system_memory_avail_percentage_lower_bound.
Condition 2: The number of partition transaction structures to be reused exceeds the threshold specified by part_trans_task_reusable_count_upper_bound. || The number of tasks to be sequenced exceeds the threshold specified by ready_to_seq_task_upper_bound.
Condition 3 (since OceanBase Database V3.x): The number of tasks to be persisted exceeds the threshold specified by storager_task_count_upper_bound. && The memory held by obcdc exceeds the throttling triggering threshold (memory_limit) multiplied by the percentage of memory used by the persistence module in the throttling memory (storager_mem_percentage).

Throttling triggering condition: ((Condition 1 && Condition 2) || Condition 3) || (pause_fetcher != 0).

The following table shows the automatic adjustment strategy for the direct_load_inc_thread_num and direct_load_inc_queue_backlog_lowest_tolerance parameters.

memory_limit	2G	4G	8G	16G	32G	128G
direct_load_inc_thread_num	1	1	1	2	3	5
direct_load_inc_queue_backlog_lowest_tolerance	4096	8192	16384	32768	65536	131072

When the available memory is sufficient, increase direct_load_inc_thread_num to speed up the reading and parsing of incremental direct load logs, and increase direct_load_inc_queue_backlog_lowest_tolerance. When the available memory is insufficient, decrease direct_load_inc_thread_num and direct_load_inc_queue_backlog_lowest_tolerance or keep their default values.

Parameter	Description	Default value	Real-time modification supported	Remarks
enable_dump_pending_trans_info	Specifies whether to regularly collect and print statistics on the status of distributed transactions in obcdc.	0	Yes	The value `0` specifies not to regularly collect and print statistics on the status of distributed transactions in obcdc. If the value is set to `1`, the statistics are printed once every 10 seconds.
print_fetcher_slowest_ls_num	The number of partitions with the lowest log-pulling speed.	10	Yes	/
print_rpc_handle_info	Specifies whether to print information related to remote procedure calls (RPCs).	0	Yes	The value `0` specifies not to print RPC-related information.
print_stream_dispatch_info	Specifies whether to print the log stream information.	0	Yes	The value `0` specifies not to print the log stream information.
print_ls_heartbeat_info	Specifies whether to print partition heartbeat information.	0	Yes	The value `0` specifies not to print partition heartbeat information.
print_ls_serve_info	Specifies whether to print the partition service information, such as the partition status and the number of transactions of the partition.	0	Yes	The value `0` specifies not to print the partition service information, such as the partition status and the number of transactions of the partition.
print_participant_not_serve_info	Specifies whether to print the information about all transactions that are not in service (no data is generated) for the distributed transaction.	0	Yes	The value `0` specifies not to print the information about all transactions that are not in service (no data is generated) for the distributed transaction.
print_ls_server_list_update_info	Specifies whether to print the details of the servers when the list of partition servers is updated.	0	Yes	The value `0` specifies not to print the details of the servers when the list of partition servers is updated.
enable_formatter_print_log	Specifies whether to enable formatter to generate logs whose formatting data is omitted.	0	Yes	The value `0` specifies not to enable formatter to generate logs whose formatting data is omitted.

Parameter	Description	Default value	Real-time modification supported	Remarks
enable_direct_load_inc	Specifies whether to synchronize data imported in incremental direct load mode.	0	No	In V4.3.1, data imported in incremental direct load mode is not synchronized by default.

obcdc V4.1 can obtain metadata such as information about schemas and log streams from data dictionaries, without the need to pull logs from OBServer nodes by using RPCs.

Parameter	Description	Default value	Real-time modification supported	Remarks
meta_data_refresh_mode	The mode for obtaining metadata such as information about schemas and log streams.	online	No	online mode: obcdc queries OBServer nodes for schema information by using SchemaService. In this mode, obcdc must be able to access OBServer nodes. data_dict mode: obcdc parses schema information based on the data dictionaries in logs.

Parameter	Description	Default value	Real-time modification supported	Remarks
skip_rename_tenant_ddl	Specifies whether to ignore DDL statements that rename a tenant.	0	Yes	The renamed tenant is not affected if it is not included in the obcdc synchronization allowlist. Otherwise, an error message is displayed and the process is terminated. This is because the rename operation overruns the allowlist restriction. In this case, we recommend that you modify the allowlist to support the tenants before and after the rename operation. When the value is set to `true`, the system will skip the DDL statements of the renamed tenant and continue the data synchronization.
enable_oracle_mode_match_case_sensitive	The case sensitivity of tenants against the blocklist or allowlist in the Oracle mode of OceanBase Database.	0	No	/

Parameter	Description	Default value	Real-time modification supported	Remarks
ls_count_upper_limit	The number of partition progress values.	2000000	No	A maximum of 200 million partitions are supported.
check_switch_server_interval_min	The interval, in minutes, of periodic partition check for the necessity of switching log-pulling servers.	30	Yes	/

Parameter	Description	Default value	Real-time modification supported	Remarks
access_systable_helper_thread_num	The maximum number of connections in the connection pool for SQL execution.	64	No	The value range is [48, 1024].
rs_sql_connect_timeout_sec	The timeout period for SQL connections of the RootService.	40	Yes	/
rs_sql_query_timeout_sec	The timeout period for SQL requests of the RootService.	30	Yes	/
tenant_sql_connect_timeout_sec	The timeout period for SQL connections of a tenant.	40	Yes	/
tenant_sql_query_timeout_sec	The timeout period for SQL requests of a tenant.	30	Yes	/
sql_server_change_interval_sec	The time interval, in seconds, for changing the SQL execution server.	60	Yes	/

Filter data based on cluster_id

obcdc allows you to filter data based on the cluster_id blocklist. Although OceanBase Database specifies a valid cluster_id range, you can specify the cluster_id values to filter out the following unwanted data in a synchronization task. For more information about how to configure cluster_id values, see ob_org_cluster_id.

The data that is not included in the valid cluster_id range specified by OceanBase Database and OceanBase Migration Service (OMS). The value range is [1, 4294901759] U [4294901760, 4294967295].
The data whose cluster_id is specified in the cluster_id_black_list field.
Each cluster ID in the cluster_id_black_list field must range from cluster_id_value_min to cluster_id_value_max.

Parameter	Description	Default value	Real-time modification supported	Remarks
cluster_id_black_list	The blocklist of cluster IDs.	`\\|`	No	Separate multiple cluster IDs with vertical bars (`\\|`). Each cluster ID ranges from `cluster_id_value_min` to `cluster_id_value_max`.
cluster_id_black_value_min	The lower limit of cluster IDs in the synchronization blocklist.	2147473648	No	/
cluster_id_black_value_min	The upper limit of cluster IDs in the synchronization blocklist.	2147483647	No	/

obcdc can send SQL and RPC requests to OBServer nodes. OceanBase Database provides parameters that allow you to block all requests sent to specific servers.

In addition, as obcdc pulls logs at the partition level, a built-in blocklist is provided to add servers that have timed out or errors when pulling partition logs to the blocklist. Servers are automatically added to or removed from the blocklist.

Parameter	Description	Default value	Real-time modification supported	Remarks
server_blacklist	A blocklist of OBServer nodes that are blocked from receiving RPC requests from obcdc.	`\\|`	Yes	The information about each OBServer node must be in the format of `svr_ip:rpc_port`. Separate the information about multiple OBServer nodes with vertical bars (`\\|`). Logs are not pulled from the OBServer nodes in the blocklist. When an OBServer node cannot provide log services due to reasons such as network partitioning and high latency, you can manually add the node to the blocklist.
sql_server_blacklist	A blocklist of OBServer nodes that are blocked from receiving SQL requests from obcdc.	`\\|`	Yes	The information about each OBServer node must be in the format of `svr_ip:rpc_port`. Separate the information about multiple OBServer nodes with vertical bars (`\\|`).

Partition-level blocklist parameters (generally not modified)

Parameter	Description	Default value	Real-time modification supported	Remarks
blacklist_survival_time_sec	The waiting time, in seconds, of servers in the blocklist.	30	No	/
blacklist_survival_time_upper_limit_min	The maximum period, in minutes, of servers in the blocklist.	4	Yes	/
blacklist_survival_time_penalty_period_min	The penalty time interval threshold, in minutes. If a server is added to the blocklist again within this time interval, the time for the server to stay in the blocklist is doubled.	1	Yes	/
blacklist_history_overdue_time_min	The period, in minutes, after which a server is deleted from the blocklist history.	30	Yes	The minimum value is `10`.
blacklist_history_clear_interval_min	The time interval, in minutes, for clearing the information about servers in the blocklist.	20	Yes	The minimum value is `10`.

Parameter	Description	Default value	Real-time modification supported
all_server_cache_update_interval_sec	The time interval, in seconds, for updating the cached list of servers.	5	Yes
all_zone_cache_update_interval_sec	The time interval, in seconds, for updating the cached zone information.	5	Yes

Parameter	Description	Default value	Real-time modification supported	Remarks
idle_pool_thread_num	The number of threads that process the pending partition-level log-pulling tasks.	4	No	The value range is [1, 32].
dead_pool_thread_num	The number of threads that recycle the partition-level log-pulling tasks.	1	No	The value range is [1, 32].
stream_worker_thread_num	The number of threads that dispatch the partition-level log-pulling tasks.	8	No	The value range is [1, 64].
start_lsn_locator_thread_num	The number of threads that locate the ID of the starting partition log.	4	No	The value range is [1, 32].
lob_data_merger_thread_num	The number of threads that process large object (LOB) data.	2	No	The value rang is [1, +∞).
start_lsn_locator_locate_count	The number of requests that complete the task of locating the starting partition log.	1	N	The minimum value is `1`. To locate the ID of the starting partition log, the follower partitions of the specified number must return the same starting log ID.
skip_start_lsn_locator_result_consistent_check	Specifies whether to skip checking the consistency of the starting log ID.	No	No	/
svr_stream_cached_count	The initial size of the object pool of the server log stream.	16	No	The minimum value is `1`.
fetch_stream_cached_count	The initial number of logs in the object pool of the partition log stream.	16	No	The minimum value is `1`.
start_lsn_locator_rpc_timeout_sec	The timeout period, in seconds, of RPC requests for locating the starting partition log ID.	60	Yes	The minimum value is `1`.
start_lsn_locator_batch_count	The batch number of the RPC requests for locating the starting partition log ID.	2000	Yes	The minimum value is `1`.
heartbeat_interval_sec	The time interval, in seconds, to send RPC requests for partition heartbeats.	1	Yes	The minimum value is `1`.
fetch_log_rpc_timeout_sec	The timeout period, in seconds, of RPC requests for pulling partition logs.	15	Yes	The minimum value is `1`.
progress_limit_sec_for_dml	The maximum number of logs that can be pulled for DML operations.	300	Yes	The minimum value is `1`. Log-pulling in some partitions can be much faster than others. To ensure that the log-pulling progress is roughly at the same pace across partitions, the maximum number of DML logs that can be provided by the server is limited to the sum of the minimum number of pulled logs among all partitions and the value of the `progress_limit_sec_for_dml` parameter.
ls_fetch_progress_update_timeout_sec	The timeout threshold, in seconds, of RPC requests for pulling partition logs.	3	Yes	The minimum value is `1`.
ls_fetch_progress_update_timeout_sec_for_lagged_replica	The timeout threshold, in seconds, of pulling logs from the lagged replica.	15	Yes	The minimum value is `1`.
enable_continue_use_cache_server_list	Specifies whether to use the server information in the cache.	0	No	Enable this option when the sys tenant is abnormal but the user tenants are normal.
fetching_log_mode	The log pulling mode.	integrated	No	integrated mode: This is the default log pulling mode in which obcdc sends RPC requests to an OBServer node to pull logs. In this case, you must configure the address (`cluter_url` or `rootserver_list`) of the OBServer node and the username (`cluster_user`) and password (`cluster_password`) in the sys tenant. direct mode: In this mode, obcdc directly consumes archived logs without the need to send RPC requests to the OBServer node to pull logs. In this case, you must configure the archive destination in the form of a Network File System (NFS) path or Object Storage Service (OSS) information. For more information about the archive destination, see Overview. The server where obcdc is located must be able to directly access the archive destination. Notice obcdc cannot pull discontinuous archived logs.

Parameter	Description	Default value	Real-time modification supported	Remarks
region	The region from which obcdc preferentially pulls logs.	default_region	Yes	The region is queried from the internal table of OceanBase Database. obcdc preferentially pulls logs from OBServer nodes in the specified region.

Parameter	Description	Default value	Value range	Real-time modification supported
io_thread_num	The number of I/O threads for RPC requests.	4	[1, +∞)	No
rpc_result_cached_count	The initial number of pulled logs in the object pool of RPC requests for pulling logs.	16	[1, +∞)	No
rpc_process_handler_time_upper_limit_msec	The maximum time, for processing an RPC request.	200	[1, +∞)	Yes
rpc_result_count_per_rpc_upper_limit	The maximum number of unprocessed results of the log-pulling RPC request in a log stream.	16	[1, +∞)	Yes

Parameter	Description	Default value	Real-time modification supported	Remarks
ssl_client_authentication	Specifies whether to enable secure communication.	0	No	The default value is `0`, which specifies to disable secure communication.
ssl_external_kms_info	The secure communication method.	file	No	For external communication, only the file mode is supported. You must create a wallet directory in the boot directory of obcdc, and put the following key file in the wallet directory: ca.pem/client-cert.pem/client-key.pem.

Parameter	Description	Default value	Value range	Real-time modification supported
sequencer_thread_num	The number of threads in the thread pool for sequencing distributed transactions.	5	[1, +∞)	No
sequencer_queue_length	The number of partition transactions waiting to be sequenced.	102400	[1, +∞)	No

Parameter	Description	Default value	Value range	Real-time modification supported
redo_dispatched_memory_limit_exceed_ratio	Specifies the size limit of the redo logs to be processed when `enable_output_trans_order_by_sql_operation` is set to `1`. To be specific, the size of the redo logs allowed to be processed in the memory is `redo_dispatched_memory_limit_exceed_ratio` * `redo_dispatcher_memory_limit`.	2	[1, +∞)	Yes
redo_dispatcher_memory_limit	The size limit of the redo logs to be processed.	512 MB	[128 MB, +∞)	Yes
extra_redo_dispatch_memory_size	The extra redo size allocated to skew participants to avoid deadlocks, which may cause obcdc not to generate data in a data skew scenario.	4 MB	[0 MB, 512 MB]	Yes

Parameter	Description	Default value	Value range	Real-time modification supported
msg_sorter_task_count_upper_limit	The maximum number of tasks for the row data sorting module in a transaction.	200000	[1, +∞)	No
msg_sorter_thread_num	The total number of threads for the row data sorting module in a transaction.	1	[1, 32]	No

Parameters valid only in persistence mode

Parameter	Description	Default value	Real-time modification supported
storager_thread_num	The number of threads in the thread pool of the storager module.	10	No
storager_queue_length	The number of tasks to be persisted.	102400	No

Parameter	Description	Default value	Real-time modification supported
reader_thread_num	The number of threads in the thread pool for reading data from the storager module.	10	No
reader_queue_length	The number of data deserialization tasks waiting to be processed.	102400	No

Parameter	Description	Default value	Value range	Real-time modification supported
batch_buf_count	The number of memory buffers for batch redo log persistence.	10	[5, +∞)	No
batch_buf_size	The size of a memory buffer for batch redo log persistence.	20 MB	[2 MB, +∞)	No

Parameter	Description	Default value	Real-time modification supported	Remarks
dml_parser_thread_num	The number of threads in the thread pool for parsing DML statements.	5	No	The minimum value is `1`.
ddl_parser_thread_num	The number of threads in the thread pool for parsing DDL statements.	1	No	The minimum value is `1`.
skip_reversed_schema_version	Specifies whether to ignore schema version rollback.	0	No	Generally, the schema version monotonically increases during the processing of DDL statements. The rollback of the schema version indicates an exception. However, you can use this parameter to skip the exception.

Parameter	Description	Default value	Real-time modification supported	Remarks
formatter_thread_num	The number of threads in the thread pool for data formatting.	10	No	The minimum value is `1`.
skip_dirty_data	Specifies whether to skip data exceptions.	0	Yes	Current exceptions: Non-full column logging. This means that commit logs (clogs) recorded only columns that have been changed. Parameter: `binlog_row_image`. Exceptions in DDL statements of the tenant restored from a physical backup.

Parameter	Description	Default value	Real-time modification supported	Remarks
enable_output_trans_order_by_sql_operation	Specifies whether to generate data rows in the transaction in the order that the SQL statements are executed.	0	No	The execution order refers to the order in which OceanBase Database makes changes to the data. It may not be the same as the order in which the SQL statements are sent from the client.
sort_trans_participants	Specifies whether to sort SQL statements by the distributed transaction participants.	1	No	The parameter specifies whether to sort statements by the partition key. You can maintain a stable statement output sequence by using this parameter together with the `enable_output_trans_order_by_sql_operation` parameter.
enable_output_hidden_primary_key	Specifies whether to generate the hidden primary keys of tables without primary keys.	0	No	You can generate the hidden primary keys of tables without primary keys by setting the parameter value to `1`.
enable_convert_timestamp_to_unix_timestamp	Specifies whether to convert a timestamp to an integer in the Unix format.	0	No	/
enable_output_invisible_column	Specifies whether to generate the hidden columns.	0	No	/
output_heartbeat_interval_msec	The time interval, for generating the information about security timestamps.	3	Yes	/

Parameter	Description	Default value	Real-time modification supported	Remarks
resource_collector_thread_num	The number of threads in the thread pool for recycling resources.	10	No	The minimum value is `1`.
resource_collector_thread_num_for_br	The number of threads in the thread pool for recycling binlog records.	7	No	The value of this parameter must be larger than that of the `resource_collector_thread_num` parameter.

Notice

We recommend that you do not modify the parameters that are not listed in this topic.

obcdc parameters

Cluster parameters

Metadata parameters

Working mode-related parameters

Synchronization granularity

Allowlist- and blocklist-related parameters

Note

Multi-instance-related parameters

Monitoring-related parameters

Throttling

Notice

Notice

Parameters related to the monitoring information output

Feature control-related parameters

Metadata management-related parameters

Tenant management-related parameters

Fetcher module-related parameters

SQL query-related parameters

Filter data based on cluster_id

Parameters related to server-level blocklists

Partition-level blocklist parameters (generally not modified)

Server cache-related parameters

Log pulling-related parameters

Notice

Parameters related to the log pulling priority

RPC module-related parameters (modifications not recommended)

Secure communication-related parameters

Sequencer module-related parameters

Parameters related to the REDO read control module

Parameters related to the row data sorting module

Parameters valid only in persistence mode

Storager module-related parameters

Parameters related to the data processor module

Parameters related to batch redo log persistence

Parser module-related parameters

Formatter module-related parameters

Parameters related to the binlog record output

Resource recycling-related parameters (modifications not recommended)

Notice