mz_internal

The following sections describe the available objects in the mz_internal schema.

mz_recent_activity_log

The mz_recent_activity_log view contains a log of the SQL statements that have been issued to Materialize in the last three days, along with various metadata about them.

Entries in this log may be sampled. The sampling rate is controlled by the configuration parameter statement_logging_sample_rate, which may be set to any value between 0 and 1. For example, to disable statement logging entirely for a session, execute SET statement_logging_sample_rate TO 0. Materialize may apply a lower sampling rate than the one set in this parameter.

The view can be accessed by Materialize superusers or users that have been granted the mz_monitor role.

Field	Type	Meaning
execution_id	uuid	An ID that is unique for each executed statement.
sample_rate	double precision	The actual rate at which the statement was sampled.
cluster_id	text	The ID of the cluster the statement execution was directed to. Corresponds to mz_clusters.id.
application_name	text	The value of the application_name configuration parameter at execution time.
cluster_name	text	The name of the cluster with ID cluster_id at execution time.
database_name	text	The value of the database configuration parameter at execution time.
search_path	text list	The value of the search_path configuration parameter at execution time.
transaction_isolation	text	The value of the transaction_isolation configuration parameter at execution time.
execution_timestamp	uint8	The logical timestamp at which execution was scheduled.
transient_index_id	text	The internal index of the compute dataflow created for the query, if any.
params	text array	The parameters with which the statement was executed.
mz_version	text	The version of Materialize that was running when the statement was executed.
began_at	timestamp with time zone	The wall-clock time at which the statement began executing.
finished_at	timestamp with time zone	The wall-clock time at which the statement finished executing.
finished_status	text	The final status of the statement (e.g., success, canceled, error, or aborted). aborted means that Materialize exited before the statement finished executing.
error_message	text	The error message, if the statement failed.
result_size	bigint	The size in bytes of the result, for statements that return rows.
rows_returned	bigint	The number of rows returned, for statements that return rows.
execution_strategy	text	For SELECT queries, the strategy for executing the query. constant means computed in the control plane without the involvement of a cluster, fast-path means read by a cluster directly from an in-memory index, and standard means computed by a temporary dataflow.
transaction_id	uint8	The ID of the transaction that the statement was part of. Note that transaction IDs are only unique per session.
prepared_statement_id	uuid	An ID that is unique for each prepared statement. For example, if a statement is prepared once and then executed multiple times, all executions will have the same value for this column (but different values for execution_id).
sql_hash	bytea	An opaque value uniquely identifying the text of the query.
prepared_statement_name	text	The name given by the client library to the prepared statement.
session_id	uuid	An ID that is unique for each session. Corresponds to mz_sessions.id.
prepared_at	timestamp with time zone	The time at which the statement was prepared.
statement_type	text	The type of the statement, e.g. select for a SELECT query, or NULL if the statement was empty.
throttled_count	uint8	The number of statements that were dropped due to throttling before the current one was seen. If you have a very high volume of queries and need to log them without throttling, contact our team.
initial_application_name	text	The initial value of application_name at the beginning of the session.
authenticated_user	text	The name of the user for which the session was established.
sql	text	The SQL text of the statement.

mz_aws_connections

The mz_aws_connections table contains a row for each AWS connection in the system.

Field	Type	Meaning
id	text	The ID of the connection.
endpoint	text	The value of the ENDPOINT option, if set.
region	text	The value of the REGION option, if set.
access_key_id	text	The value of the ACCESS KEY ID option, if provided in line.
access_key_id_secret_id	text	The ID of the secret referenced by the ACCESS KEY ID option, if provided via a secret.
secret_access_key_secret_id	text	The ID of the secret referenced by the SECRET ACCESS KEY option, if set.
session_token	text	The value of the SESSION TOKEN option, if provided in line.
session_token_secret_id	text	The ID of the secret referenced by the SESSION TOKEN option, if provided via a secret.
assume_role_arn	text	The value of the ASSUME ROLE ARN option, if set.
assume_role_session_name	text	The value of the ASSUME ROLE SESSION NAME option, if set.
principal	text	The ARN of the AWS principal Materialize will use when assuming the provided role, if the connection is configured to use role assumption.
external_id	text	The external ID Materialize will use when assuming the provided role, if the connection is configured to use role assumption.
example_trust_policy	jsonb	An example of an IAM role trust policy that allows this connection’s principal and external ID to assume the role.

mz_aws_privatelink_connection_status_history

The mz_aws_privatelink_connection_status_history table contains a row describing the historical status for each AWS PrivateLink connection in the system.

Field	Type	Meaning
occurred_at	timestamp with time zone	Wall-clock timestamp of the status change.
connection_id	text	The unique identifier of the AWS PrivateLink connection. Corresponds to mz_catalog.mz_connections.id.
status	text	The status of the connection: one of pending-service-discovery, creating-endpoint, recreating-endpoint, updating-endpoint, available, deleted, deleting, expired, failed, pending, pending-acceptance, rejected, or unknown.

mz_aws_privatelink_connection_statuses

The mz_aws_privatelink_connection_statuses table contains a row describing the most recent status for each AWS PrivateLink connection in the system.

Field	Type	Meaning
id	text	The ID of the connection. Corresponds to mz_catalog.mz_connections.id.
name	text	The name of the connection.
last_status_change_at	timestamp with time zone	Wall-clock timestamp of the connection status change.
status	text

mz_cluster_deployment_lineage

The mz_cluster_deployment_lineage table shows the blue/green deployment lineage of all clusters in mz_clusters. It determines all cluster IDs that are logically the same cluster.

Field	Type	Meaning
cluster_id	text	The ID of the cluster. Corresponds to mz_clusters.id (though the cluster may no longer exist).
current_deployment_cluster_id	text	The cluster ID of the last cluster in cluster_id’s blue/green lineage (the cluster is guaranteed to exist).
cluster_name	text	The name of the cluster

mz_cluster_schedules

The mz_cluster_schedules table shows the SCHEDULE option specified for each cluster.

Field	Type	Meaning
cluster_id	text	The ID of the cluster. Corresponds to mz_clusters.id.
type	text	on-refresh, or manual. Default: manual
refresh_hydration_time_estimate	interval	The interval given in the HYDRATION TIME ESTIMATE option.

mz_cluster_replica_metrics

The mz_cluster_replica_metrics table gives the last known CPU and RAM utilization statistics for all processes of all extant cluster replicas.

At this time, we do not make any guarantees about the exactness or freshness of these numbers.

Field	Type	Meaning
replica_id	text	The ID of a cluster replica.
process_id	uint8	The ID of a process within the replica.
cpu_nano_cores	uint8	Approximate CPU usage, in billionths of a vCPU core.
memory_bytes	uint8	Approximate RAM usage, in bytes.
disk_bytes	uint8	Approximate disk usage in bytes.

mz_cluster_replica_metrics_history

The mz_cluster_replica_metrics_history table records resource utilization metrics for all processes of all extant cluster replicas.

At this time, we do not make any guarantees about the exactness or freshness of these numbers.

Field	Type	Meaning
replica_id	text	The ID of a cluster replica.
process_id	uint8	The ID of a process within the replica.
cpu_nano_cores	uint8	Approximate CPU usage in billionths of a vCPU core.
memory_bytes	uint8	Approximate memory usage in bytes.
disk_bytes	uint8	Approximate disk usage in bytes.
occurred_at	timestamp with time zone	Wall-clock timestamp at which the event occurred.

mz_cluster_replica_statuses

The mz_cluster_replica_statuses table contains a row describing the status of each process in each cluster replica in the system.

Field	Type	Meaning
replica_id	text	Materialize’s unique ID for the cluster replica.
process_id	uint8	The ID of the process within the cluster replica.
status	text	The status of the cluster replica: online or offline.
reason	text	If the cluster replica is in a offline state, the reason (if available). For example, oom-killed.
updated_at	timestamp with time zone	The time at which the status was last updated.

mz_cluster_replica_status_history

The mz_cluster_replica_status_history table records status changes for all processes of all extant cluster replicas.

Field	Type	Meaning
replica_id	text	The ID of a cluster replica.
process_id	uint8	The ID of a process within the replica.
status	text	The status of the cluster replica: online or offline.
reason	text	If the cluster replica is in an offline state, the reason (if available). For example, oom-killed.
occurred_at	timestamp with time zone	Wall-clock timestamp at which the event occurred.

mz_cluster_replica_utilization

The mz_cluster_replica_utilization view gives the last known CPU and RAM utilization statistics for all processes of all extant cluster replicas, as a percentage of the total resource allocation.

At this time, we do not make any guarantees about the exactness or freshness of these numbers.

Field	Type	Meaning
replica_id	text	The ID of a cluster replica.
process_id	uint8	The ID of a process within the replica.
cpu_percent	double precision	Approximate CPU usage in percent of the total allocation.
memory_percent	double precision	Approximate RAM usage in percent of the total allocation.
disk_percent	double precision	Approximate disk usage in percent of the total allocation.

mz_cluster_replica_utilization_history

The mz_cluster_replica_utilization_history view records resource utilization metrics for all processes of all extant cluster replicas, as a percentage of the total resource allocation.

At this time, we do not make any guarantees about the exactness or freshness of these numbers.

Field	Type	Meaning
replica_id	text	The ID of a cluster replica.
process_id	uint8	The ID of a process within the replica.
cpu_percent	double precision	Approximate CPU usage in percent of the total allocation.
memory_percent	double precision	Approximate RAM usage in percent of the total allocation.
disk_percent	double precision	Approximate disk usage in percent of the total allocation.
occurred_at	timestamp with time zone	Wall-clock timestamp at which the event occurred.

mz_cluster_replica_history

The mz_cluster_replica_history view contains information about the timespan of each replica, including the times at which it was created and dropped (if applicable).

Field	Type	Meaning
replica_id	text	The ID of a cluster replica.
size	text	The size of the cluster replica. Corresponds to mz_cluster_replica_sizes.size.
cluster_id	text	The ID of the cluster associated with the replica.
cluster_name	text	The name of the cluster associated with the replica.
replica_name	text	The name of the replica.
created_at	timestamp with time zone	The time at which the replica was created.
dropped_at	timestamp with time zone	The time at which the replica was dropped, or NULL if it still exists.
credits_per_hour	numeric	The number of compute credits consumed per hour. Corresponds to mz_cluster_replica_sizes.credits_per_hour.

mz_cluster_replica_name_history

The mz_cluster_replica_name_history view contains historical information about names of each cluster replica.

Field	Type	Meaning
occurred_at	timestamp with time zone	The time at which the cluster replica was created or renamed. NULL if it’s a built in system cluster replica.
id	text	The ID of the cluster replica.
previous_name	text	The previous name of the cluster replica. NULL if there was no previous name.
new_name	text	The new name of the cluster replica.

mz_internal_cluster_replicas

The mz_internal_cluster_replicas table lists the replicas that are created and maintained by Materialize support.

Field	Type	Meaning
id	text	The ID of a cluster replica. Corresponds to mz_cluster_replicas.id.

mz_pending_cluster_replicas

The mz_pending_cluster_replicas table lists the replicas that were created during managed cluster alter statement that has not yet finished. The configurations of these replica may differ from the cluster’s configuration.

Field	Type	Meaning
id	text	The ID of a cluster replica. Corresponds to mz_cluster_replicas.id.

mz_comments

The mz_comments table stores optional comments (i.e., descriptions) for objects in the database.

Field	Type	Meaning
id	text	The ID of the object. Corresponds to mz_objects.id.
object_type	text	The type of object the comment is associated with.
object_sub_id	integer	For a comment on a column of a relation, the column number. NULL for other object types.
comment	text	The comment itself.

mz_compute_dependencies

The mz_compute_dependencies table describes the dependency structure between each compute object (index, materialized view, or subscription) and the sources of its data.

In contrast to mz_object_dependencies, this table only lists dependencies in the compute layer. SQL objects that don’t exist in the compute layer (such as views) are omitted.

Field	Type	Meaning
object_id	text	The ID of a compute object. Corresponds to mz_catalog.mz_indexes.id, mz_catalog.mz_materialized_views.id, or mz_internal.mz_subscriptions.
dependency_id	text	The ID of a compute dependency. Corresponds to mz_catalog.mz_indexes.id, mz_catalog.mz_materialized_views.id, mz_catalog.mz_sources.id, or mz_catalog.mz_tables.id.

mz_compute_hydration_statuses

The mz_compute_hydration_statuses view describes the per-replica hydration status of each compute object (index, materialized view).

A compute object is hydrated on a given replica when it has fully processed the initial snapshot of data available in its inputs.

Field	Type	Meaning
object_id	text	The ID of a compute object. Corresponds to mz_catalog.mz_indexes.id or mz_catalog.mz_materialized_views.id
replica_id	text	The ID of a cluster replica.
hydrated	boolean	Whether the compute object is hydrated on the replica.
hydration_time	interval	The amount of time it took for the replica to hydrate the compute object.

mz_compute_operator_hydration_statuses

The mz_compute_operator_hydration_statuses table describes the dataflow operator hydration status of compute objects (indexes or materialized views).

A dataflow operator is hydrated on a given replica when it has fully processed the initial snapshot of data available in its inputs.

Field	Type	Meaning
object_id	text	The ID of a compute object. Corresponds to mz_catalog.mz_indexes.id or mz_catalog.mz_materialized_views.id.
physical_plan_node_id	uint8	The ID of a node in the physical plan of the compute object. Corresponds to a node_id displayed in the output of EXPLAIN PHYSICAL PLAN WITH (node identifiers).
replica_id	text	The ID of a cluster replica.
hydrated	boolean	Whether the node is hydrated on the replica.

mz_frontiers

The mz_frontiers table describes the frontiers of each source, sink, table, materialized view, index, and subscription in the system, as observed from the coordinator.

At this time, we do not make any guarantees about the freshness of these numbers.

Field	Type	Meaning
object_id	text	The ID of the source, sink, table, index, materialized view, or subscription.
read_frontier	mz_timestamp	The earliest timestamp at which the output is still readable.
write_frontier	mz_timestamp	The next timestamp at which the output may change.

mz_history_retention_strategies

The mz_history_retention_strategies describes the history retention strategies for tables, sources, indexes, materialized views that are configured with a history retention period.

Field	Type	Meaning
id	text	The ID of the object.
strategy	text	The strategy. FOR is the only strategy, and means the object’s compaction window is the duration of the value field.
value	jsonb	The value of the strategy. For FOR, is a number of milliseconds.

mz_hydration_statuses

The mz_hydration_statuses view describes the per-replica hydration status of each object powered by a dataflow.

A dataflow-powered object is hydrated on a given replica when the respective dataflow has fully processed the initial snapshot of data available in its inputs.

Field	Type	Meaning
object_id	text	The ID of a dataflow-powered object. Corresponds to mz_catalog.mz_indexes.id, mz_catalog.mz_materialized_views.id, mz_internal.mz_subscriptions, mz_catalog.mz_sources.id, or mz_catalog.mz_sinks.id.
replica_id	text	The ID of a cluster replica.
hydrated	boolean	Whether the object is hydrated on the replica.

mz_index_advice

The mz_index_advice view provides advice on opportunities to optimize resource usage (memory and CPU) in Materialize. The advice provided suggests either creating indexes or materialized views to precompute intermediate results that can be reused across several objects, or removing unnecessary indexes or materialized views.

Known limitations

The suggestions are based on the graph of dependencies between objects and do not take into account other important factors, like the actual usage patterns and execution plans. This means that following the advice in this view might not always lead to resource usage optimizations. In some cases, the provided advice might even lead to suboptimal execution plans or even increased resource usage. For example:

• If a materialized view or an index has been created for direct querying, the dependency graph will not reflect this nuance and mz_index_advice might recommend using and unindexed view instead. In this case, you should refer to the the reference documentation for query optimization instead.
• If a view is depended on by multiple objects that use very selective filters, or multiple projections that can be pushed into or even beyond the view, adding an index may increase resource usage.
• If an index has been created to enable delta joins, removing it may lead to lower memory utilization, but the delta join optimization will no longer be used in the join implementation.

To guarantee that there are no regressions given your specific usage patterns, it’s important to test any changes in a development environment before deploying the changes to production.

Field	Type	Meaning
object_id	text	The ID of the object. Corresponds to mz_objects.id.
hint	text	A suggestion to either change the object (e.g. create an index, turn a materialized view into an indexed view) or keep the object unchanged.
details	text	Additional details on why the hint was proposed based on the dependencies of the object.
referenced_object_ids	[list]	The IDs of objects referenced by details. Corresponds to mz_objects.id.

mz_materialization_dependencies

The mz_materialization_dependencies view describes the dependency structure between each materialization (materialized view, index, or sink) and the sources of its data.

In contrast to mz_object_dependencies, this view only lists dependencies in the dataflow layer. SQL objects that don’t exist in the dataflow layer (such as views) are omitted.

Field	Type	Meaning
object_id	text	The ID of a materialization. Corresponds to mz_catalog.mz_indexes.id, mz_catalog.mz_materialized_views.id, or mz_catalog.mz_sinks.id.
dependency_id	text	The ID of a dataflow dependency. Corresponds to mz_catalog.mz_indexes.id, mz_catalog.mz_materialized_views.id, mz_catalog.mz_sources.id, or mz_catalog.mz_tables.id.

mz_materialization_lag

The mz_materialization_lag view describes the difference between the input frontiers and the output frontier for each materialized view, index, and sink in the system. For hydrated dataflows, this lag roughly corresponds to the time it takes for updates at the inputs to be reflected in the output.

At this time, we do not make any guarantees about the freshness of these numbers.

Field	Type	Meaning
object_id	text	The ID of the materialized view, index, or sink.
local_lag	interval	The amount of time the materialization lags behind its direct inputs.
global_lag	interval	The amount of time the materialization lags behind its root inputs (sources and tables).
slowest_local_input_id	text	The ID of the slowest direct input.
slowest_global_input_id	text	The ID of the slowest root input.

mz_materialized_view_refresh_strategies

The mz_materialized_view_refresh_strategies table shows the refresh strategies specified for materialized views. If a materialized view has multiple refresh strategies, a row will exist for each.

Field	Type	Meaning
materialized_view_id	text	The ID of the materialized view. Corresponds to mz_catalog.mz_materialized_views.id
type	text	at, every, or on-commit. Default: on-commit
interval	interval	The refresh interval of a REFRESH EVERY option, or NULL if the type is not every.
aligned_to	timestamp with time zone	The ALIGNED TO option of a REFRESH EVERY option, or NULL if the type is not every.
at	timestamp with time zone	The time of a REFRESH AT, or NULL if the type is not at.

mz_materialized_view_refreshes

The mz_materialized_view_refreshes table shows the time of the last successfully completed refresh and the time of the next scheduled refresh for each materialized view with a refresh strategy other than on-commit.

Field	Type	Meaning
materialized_view_id	text	The ID of the materialized view. Corresponds to mz_catalog.mz_materialized_views.id
last_completed_refresh	mz_timestamp	The time of the last successfully completed refresh. NULL if the materialized view hasn’t completed any refreshes yet.
next_refresh	mz_timestamp	The time of the next scheduled refresh. NULL if the materialized view has no future scheduled refreshes.

mz_object_dependencies

The mz_object_dependencies table describes the dependency structure between all database objects in the system.

Field	Type	Meaning
object_id	text	The ID of the dependent object. Corresponds to mz_objects.id.
referenced_object_id	text	The ID of the referenced object. Corresponds to mz_objects.id.

mz_object_fully_qualified_names

The mz_object_fully_qualified_names view enriches the mz_catalog.mz_objects view with namespace information.

Field	Type	Meaning
id	text	Materialize’s unique ID for the object.
name	text	The name of the object.
object_type	text	The type of the object: one of table, source, view, materialized view, sink, index, connection, secret, type, or function.
schema_id	text	The ID of the schema to which the object belongs. Corresponds to mz_schemas.id.
schema_name	text	The name of the schema to which the object belongs. Corresponds to mz_schemas.name.
database_id	text	The ID of the database to which the object belongs. Corresponds to mz_databases.id.
database_name	text	The name of the database to which the object belongs. Corresponds to mz_databases.name.
cluster_id	text	The ID of the cluster maintaining the source, materialized view, index, or sink. Corresponds to mz_clusters.id. NULL for other object types.

mz_object_lifetimes

The mz_object_lifetimes view enriches the mz_catalog.mz_objects view with information about the last lifetime event that occurred for each object in the system.

Field	Type	Meaning
id	text	Materialize’s unique ID for the object.
previous_id	text	The object’s previous ID, if one exists.
object_type	text	The type of the object: one of table, source, view, materialized view, sink, index, connection, secret, type, or function.
event_type	text	The lifetime event, either create or drop.
occurred_at	timestamp with time zone	Wall-clock timestamp of when the event occurred.

mz_object_history

The mz_object_history view enriches the mz_catalog.mz_objects view with historical information about each object in the system.

Field	Type	Meaning
id	text	Materialize’s unique ID for the object.
cluster_id	text	The object’s cluster ID. NULL if the object has no associated cluster.
object_type	text	The type of the object: one of table, source, view, materialized view, sink, index, connection, secret, type, or function.
created_at	timestamp with time zone	Wall-clock timestamp of when the object was created. NULL for built in system objects.
dropped_at	timestamp with time zone	Wall-clock timestamp of when the object was dropped. NULL for built in system objects or if the object hasn’t been dropped.

mz_object_transitive_dependencies

The mz_object_transitive_dependencies view describes the transitive dependency structure between all database objects in the system. The view is defined as the transitive closure of mz_object_dependencies.

Field	Type	Meaning
object_id	text	The ID of the dependent object. Corresponds to mz_objects.id.
referenced_object_id	text	The ID of the (possibly transitively) referenced object. Corresponds to mz_objects.id.

mz_notices

The mz_notices view contains a list of currently active notices emitted by the system. The view can be accessed by Materialize superusers.

Field	Type	Meaning
id	text	Materialize’s unique ID for this notice.
notice_type	text	The notice type.
message	text	A brief description of the issue highlighted by this notice.
hint	text	A high-level hint that tells the user what can be improved.
action	text	A concrete action that will resolve the notice.
redacted_message	text	A redacted version of the message column. NULL if no redaction is needed.
redacted_hint	text	A redacted version of the hint column. NULL if no redaction is needed.
redacted_action	text	A redacted version of the action column. NULL if no redaction is needed.
action_type	text	The type of the action string (sql_statements for a valid SQL string or plain_text for plain text).
object_id	text	The ID of the materialized view or index. Corresponds to mz_objects.id. For global notices, this column is NULL.
created_at	timestamp with time zone	The time at which the notice was created. Note that some notices are re-created on environmentd restart.

mz_notices_redacted

The mz_notices_redacted view contains a redacted list of currently active optimizer notices emitted by the system. The view can be accessed by Materialize superusers and Materialize support.

Field	Type	Meaning
id	text	Materialize’s unique ID for this notice.
notice_type	text	The notice type.
message	text	A redacted brief description of the issue highlighted by this notice.
hint	text	A redacted high-level hint that tells the user what can be improved.
action	text	A redacted concrete action that will resolve the notice.
action_type	text	The type of the action string (sql_statements for a valid SQL string or plain_text for plain text).
object_id	text	The ID of the materialized view or index. Corresponds to mz_objects.id. For global notices, this column is NULL.
created_at	timestamp with time zone	The time at which the notice was created. Note that some notices are re-created on environmentd restart.

mz_postgres_sources

The mz_postgres_sources table contains a row for each PostgreSQL source in the system.

Field	Type	Meaning
id	text	The ID of the source. Corresponds to mz_catalog.mz_sources.id.
replication_slot	text	The name of the replication slot in the PostgreSQL database that Materialize will create and stream data from.
timeline_id	uint8	The PostgreSQL timeline ID determined on source creation.

mz_postgres_source_tables

The mz_postgres_source_tables table contains the mapping between each Materialize subsource or table and the corresponding upstream PostgreSQL table being ingested.

Field	Type	Meaning
id	text	The ID of the subsource or table. Corresponds to mz_catalog.mz_sources.id or mz_catalog.mz_tables.id.
schema_name	text	The schema of the upstream table being ingested.
table_name	text	The name of the upstream table being ingested.

mz_mysql_source_tables

The mz_mysql_source_tables table contains the mapping between each Materialize subsource or table and the corresponding upstream MySQL table being ingested.

Field	Type	Meaning
id	text	The ID of the subsource or table. Corresponds to mz_catalog.mz_sources.id or mz_catalog.mz_tables.id.
schema_name	text	The schema (or, database) of the upstream table being ingested.
table_name	text	The name of the upstream table being ingested.

mz_kafka_source_tables

The mz_kafka_source_tables table contains the mapping between each Materialize table and the corresponding upstream Kafka topic being ingested.

Field	Type	Meaning
id	text	The ID of the table. Corresponds to mz_catalog.mz_tables.id.
topic	text	The topic being ingested.
envelope_type	text	The envelope type: none, upsert, or debezium. NULL for other source types.
key_format	text	The format of the Kafka message key: avro, protobuf, csv, regex, bytes, json, text, or NULL.
value_format	text	The format of the Kafka message value: avro, protobuf, csv, regex, bytes, json, text. NULL for other source types.

mz_sessions

The mz_sessions table contains a row for each active session in the system.

Field	Type	Meaning
id	uuid	The globally unique ID of the session.
connection_id	uint4	The connection ID of the session. Unique only for active sessions and can be recycled. Corresponds to pg_backend_pid().
role_id	text	The role ID of the role that the session is logged in as. Corresponds to mz_catalog.mz_roles.
client_ip	text	The IP address of the client that initiated the session.
connected_at	timestamp with time zone	The time at which the session connected to the system.

mz_network_policies

The mz_network_policies table contains a row for each network policy in the system.

Field	Type	Meaning
id	text	The ID of the network policy.
name	text	The name of the network policy.
owner_id	text	The role ID of the owner of the network policy. Corresponds to mz_catalog.mz_roles.id.
privileges	mz_aclitem array	The privileges belonging to the network policy.
oid	oid	A PostgreSQL-compatible OID for the network policy.

mz_network_policy_rules

The mz_network_policy_rules table contains a row for each network policy rule in the system.

Field	Type	Meaning
name	text	The name of the network policy rule. Can be combined with policy_id to form a unique identifier.
policy_id	text	The ID the network policy the rule is part of. Corresponds to mz_network_policy_rules.id.
action	text	The action of the rule. allow is the only supported action.
address	text	The address the rule will take action on.
direction	text	The direction of traffic the rule applies to. ingress is the only supported direction.

mz_show_network_policies

The mz_show_show_network_policies view contains a row for each network policy in the system.

mz_show_all_privileges

The mz_show_all_privileges view contains a row for each privilege granted in the system on user objects to user roles.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
database	text	The name of the database containing the object.
schema	text	The name of the schema containing the object.
name	text	The name of the privilege target.
object_type	text	The type of object the privilege is granted on.
privilege_type	text	They type of privilege granted.

mz_show_cluster_privileges

The mz_show_cluster_privileges view contains a row for each cluster privilege granted in the system on user clusters to user roles.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
name	text	The name of the cluster.
privilege_type	text	They type of privilege granted.

mz_show_database_privileges

The mz_show_database_privileges view contains a row for each database privilege granted in the system on user databases to user roles.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
name	text	The name of the database.
privilege_type	text	They type of privilege granted.

mz_show_default_privileges

The mz_show_default_privileges view contains a row for each default privilege granted in the system in user databases and schemas to user roles.

Field	Type	Meaning
object_owner	text	Privileges described in this row will be granted on objects created by object_owner.
database	text	Privileges described in this row will be granted only on objects created in database if non-null.
schema	text	Privileges described in this row will be granted only on objects created in schema if non-null.
object_type	text	Privileges described in this row will be granted only on objects of type object_type.
grantee	text	Privileges described in this row will be granted to grantee.
privilege_type	text	They type of privilege to be granted.

mz_show_object_privileges

The mz_show_object_privileges view contains a row for each object privilege granted in the system on user objects to user roles.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
database	text	The name of the database containing the object.
schema	text	The name of the schema containing the object.
name	text	The name of the object.
object_type	text	The type of object the privilege is granted on.
privilege_type	text	They type of privilege granted.

mz_show_role_members

The mz_show_role_members view contains a row for each role membership in the system.

Field	Type	Meaning
role	text	The role that member is a member of.
member	text	The role that is a member of role.
grantor	text	The role that granted membership of member to role.

mz_show_schema_privileges

The mz_show_schema_privileges view contains a row for each schema privilege granted in the system on user schemas to user roles.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
database	text	The name of the database containing the schema.
name	text	The name of the schema.
privilege_type	text	They type of privilege granted.

mz_show_system_privileges

The mz_show_system_privileges view contains a row for each system privilege granted in the system on to user roles.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
privilege_type	text	They type of privilege granted.

mz_show_all_my_privileges

The mz_show_all_my_privileges view is the same as mz_show_all_privileges, but only includes rows where the current role is a direct or indirect member of grantee.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
database	text	The name of the database containing the object.
schema	text	The name of the schema containing the object.
name	text	The name of the privilege target.
object_type	text	The type of object the privilege is granted on.
privilege_type	text	They type of privilege granted.

mz_show_my_cluster_privileges

The mz_show_my_cluster_privileges view is the same as mz_show_cluster_privileges, but only includes rows where the current role is a direct or indirect member of grantee.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
name	text	The name of the cluster.
privilege_type	text	They type of privilege granted.

mz_show_my_database_privileges

The mz_show_my_database_privileges view is the same as mz_show_database_privileges, but only includes rows where the current role is a direct or indirect member of grantee.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
name	text	The name of the cluster.
privilege_type	text	They type of privilege granted.

mz_show_my_default_privileges

The mz_show_my_default_privileges view is the same as mz_show_default_privileges, but only includes rows where the current role is a direct or indirect member of grantee.

Field	Type	Meaning
object_owner	text	Privileges described in this row will be granted on objects created by object_owner.
database	text	Privileges described in this row will be granted only on objects created in database if non-null.
schema	text	Privileges described in this row will be granted only on objects created in schema if non-null.
object_type	text	Privileges described in this row will be granted only on objects of type object_type.
grantee	text	Privileges described in this row will be granted to grantee.
privilege_type	text	They type of privilege to be granted.

mz_show_my_object_privileges

The mz_show_my_object_privileges view is the same as mz_show_object_privileges, but only includes rows where the current role is a direct or indirect member of grantee.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
database	text	The name of the database containing the object.
schema	text	The name of the schema containing the object.
name	text	The name of the object.
object_type	text	The type of object the privilege is granted on.
privilege_type	text	They type of privilege granted.

mz_show_my_role_members

The mz_show_my_role_members view is the same as mz_show_role_members, but only includes rows where the current role is a direct or indirect member of member.

Field	Type	Meaning
role	text	The role that member is a member of.
member	text	The role that is a member of role.
grantor	text	The role that granted membership of member to role.

mz_show_my_schema_privileges

The mz_show_my_schema_privileges view is the same as mz_show_schema_privileges, but only includes rows where the current role is a direct or indirect member of grantee.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
database	text	The name of the database containing the schema.
name	text	The name of the schema.
privilege_type	text	They type of privilege granted.

mz_show_my_system_privileges

The mz_show_my_system_privileges view is the same as mz_show_system_privileges, but only includes rows where the current role is a direct or indirect member of grantee.

Field	Type	Meaning
grantor	text	The role that granted the privilege.
grantee	text	The role that the privilege was granted to.
privilege_type	text	They type of privilege granted.

mz_sink_statistics

The mz_sink_statistics view contains statistics about each sink.

Counters

messages_staged, messages_committed, bytes_staged, and bytes_committed are all counters that monotonically increase. They are only useful for calculating rates to understand the general performance of your sink.

Note that:

• The non-rate values themselves are not directly comparable, because they are collected and aggregated across multiple threads/processes.

Field	Type	Meaning
id	text	The ID of the sink. Corresponds to mz_catalog.mz_sources.id.
messages_staged	uint8	The number of messages staged but possibly not committed to the sink.
messages_committed	uint8	The number of messages committed to the sink.
bytes_staged	uint8	The number of bytes staged but possibly not committed to the sink. This counts both keys and values, if applicable.
bytes_committed	uint8	The number of bytes committed to the sink. This counts both keys and values, if applicable.

mz_sink_statuses

The mz_sink_statuses view provides the current state for each sink in the system, including potential error messages and additional metadata helpful for debugging.

Field	Type	Meaning
id	text	The ID of the sink. Corresponds to mz_catalog.mz_sinks.id.
name	text	The name of the sink.
type	text	The type of the sink.
last_status_change_at	timestamp with time zone	Wall-clock timestamp of the sink status change.
status	text	The status of the sink: one of created, starting, running, stalled, failed, or dropped.
error	text	If the sink is in an error state, the error message.
details	jsonb	Additional metadata provided by the sink. In case of error, may contain a hint field with helpful suggestions.

mz_sink_status_history

The mz_sink_status_history table contains rows describing the history of changes to the status of each sink in the system, including potential error messages and additional metadata helpful for debugging.

Field	Type	Meaning
occurred_at	timestamp with time zone	Wall-clock timestamp of the sink status change.
sink_id	text	The ID of the sink. Corresponds to mz_catalog.mz_sinks.id.
status	text	The status of the sink: one of created, starting, running, stalled, failed, or dropped.
error	text	If the sink is in an error state, the error message.
details	jsonb	Additional metadata provided by the sink. In case of error, may contain a hint field with helpful suggestions.

mz_source_statistics

The mz_source_statistics view contains statistics about each source.

Field	Type	Meaning
id	text	The ID of the source. Corresponds to mz_catalog.mz_sources.id.
messages_received	uint8	The number of messages the source has received from the external system. Messages are counted in a source type-specific manner. Messages do not correspond directly to updates: some messages produce multiple updates, while other messages may be coalesced into a single update.
bytes_received	uint8	The number of bytes the source has read from the external system. Bytes are counted in a source type-specific manner and may or may not include protocol overhead.
updates_staged	uint8	The number of updates (insertions plus deletions) the source has written but not yet committed to the storage layer.
updates_committed	uint8	The number of updates (insertions plus deletions) the source has committed to the storage layer.
records_indexed	uint8	The number of individual records indexed in the source envelope state.
bytes_indexed	uint8	The number of bytes stored in the source’s internal index, if any.
rehydration_latency	interval	The amount of time it took for the source to rehydrate its internal index, if any, after the source last restarted.
snapshot_records_known	uint8	The size of the source’s snapshot, measured in number of records. See below to learn what constitutes a record.
snapshot_records_staged	uint8	The number of records in the source’s snapshot that Materialize has read. See below to learn what constitutes a record.
snapshot_committed	boolean	Whether the source has committed the initial snapshot for a source.
offset_known	uint8	The offset of the most recent data in the source’s upstream service that Materialize knows about. See below to learn what constitutes an offset.
offset_committed	uint8	The offset of the the data that Materialize has durably ingested. See below to learn what constitutes an offset.

Counter metrics

messages_received, bytes_received, updates_staged, and updates_committed are counter metrics that monotonically increase over time.

Counters are updated in a best-effort manner. An ill-timed restart of the source may cause undercounting or overcounting. As a result, counters are only useful for calculating rates to understand the general performance of your source.

For Postgres and MySQL sources, messages_received and bytes_received are collected on the top-level source, and updates_staged and updates_committed are collected on the source’s tables.

Gauge metrics

Gauge metrics reflect values that can increase or decrease over time. Gauge metrics are eventually consistent. They may lag the true state of the source by seconds or minutes, but if the source stops ingesting messages, the gauges will eventually reflect the true state of the source.

records_indexed and bytes_indexed are the size (in records and bytes respectively) of the index the source must maintain internally to efficiently process incoming data. Currently, only sources that use the upsert and Debezium envelopes must maintain an index. These gauges reset to 0 when the source is restarted, as the index must be rehydrated.

rehydration_latency represents the amount of time it took for the source to rehydrate its index after the latest restart. It is reset to NULL when a source is restarted and is populated with a duration after hydration finishes.

When a source is first created, it must process an initial snapshot of data. snapshot_records_known is the total number of records in the snapshot, and snapshot_records_staged is how many of the records the source has read so far.

The meaning of record depends on the source:

• For Kafka sources, its the total number of offsets in the snapshot.
• For Postgres and MySQL sources, its the number of rows in the snapshot.

Note that when tables are added to Postgres or MySQL sources, snapshot_records_known and snapshot_records_staged will reset as the source snapshots those new tables. The metrics will also reset if the source is restarted while the snapshot is in progres.

snapshot_committed becomes true when we have fully committed the snapshot for the given source.

offset_known and offset_committed are used to represent the progress a source is making relative to its upstream source. offset_known is the maximum offset in the upstream system that Materialize knows about. offset_committed is the offset that Materialize has durably ingested. These metrics will never decrease over the lifetime of a source.

The meaning of offset depends on the source:

• For Kafka sources, an offset is the Kafka message offset.
• For MySQL sources, an offset is the number of transactions committed across all servers in the cluster.
• For Postgres sources, an offset is a log sequence number (LSN).

mz_source_statuses

The mz_source_statuses view provides the current state for each source in the system, including potential error messages and additional metadata helpful for debugging.

Field	Type	Meaning
id	text	The ID of the source. Corresponds to mz_catalog.mz_sources.id.
name	text	The name of the source.
type	text	The type of the source.
last_status_change_at	timestamp with time zone	Wall-clock timestamp of the source status change.
status	text	The status of the source: one of created, starting, running, stalled, failed, or dropped.
error	text	If the source is in an error state, the error message.
details	jsonb	Additional metadata provided by the source. In case of error, may contain a hint field with helpful suggestions.

mz_source_status_history

The mz_source_status_history table contains a row describing the status of the historical state for each source in the system, including potential error messages and additional metadata helpful for debugging.

Field	Type	Meaning
occurred_at	timestamp with time zone	Wall-clock timestamp of the source status change.
source_id	text	The ID of the source. Corresponds to mz_catalog.mz_sources.id.
status	text	The status of the source: one of created, starting, running, stalled, failed, or dropped.
error	text	If the source is in an error state, the error message.
details	jsonb	Additional metadata provided by the source. In case of error, may contain a hint field with helpful suggestions.

mz_statement_lifecycle_history

Field	Type	Meaning
statement_id	uuid	The ID of the execution event. Corresponds to mz_recent_activity_log.execution_id
event_type	text	The type of lifecycle event, e.g. 'execution-began', 'storage-dependencies-finished', 'compute-dependencies-finished', or 'execution-finished'
occurred_at	timestamp with time zone	The time at which the event took place.

mz_subscriptions

The mz_subscriptions table describes all active SUBSCRIBE operations in the system.

Field	Type	Meaning
id	text	The ID of the subscription.
session_id	uuid	The ID of the session that runs the subscription. Corresponds to mz_sessions.id.
cluster_id	text	The ID of the cluster on which the subscription is running. Corresponds to mz_clusters.id.
created_at	timestamp with time zone	The time at which the subscription was created.
referenced_object_ids	text list	The IDs of objects referenced by the subscription. Corresponds to mz_objects.id

mz_wallclock_lag_history

The mz_wallclock_lag_history table records the historical wallclock lag, i.e., the difference between the write frontier and the current wallclock time, for each table, source, index, materialized view, and sink in the system.

Field	Type	Meaning
object_id	text	The ID of the table, source, materialized view, index, or sink. Corresponds to mz_objects.id.
replica_id	text	The ID of a replica computing the object, or NULL for persistent objects. Corresponds to mz_cluster_replicas.id.
lag	interval	The amount of time the object’s write frontier lags behind wallclock time.
occurred_at	timestamp with time zone	Wall-clock timestamp at which the event occurred.

mz_webhook_sources

The mz_webhook_sources table contains a row for each webhook source in the system.

Field	Type	Meaning
id	text	The ID of the webhook source. Corresponds to mz_sources.id.
name	text	The name of the webhook source.
url	text	The URL which can be used to send events to the source.