title_wip

### NetworkSendErrors\_*name*[​](#networksenderrors_name "Direct link to networksenderrors_name")

Number of times error (e.g. TCP retransmit) happened while sending via the network interface. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### NetworkSendPackets\_*name*[​](#networksendpackets_name "Direct link to networksendpackets_name")

Number of network packets sent via the network interface. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### NumberOfDatabases[​](#numberofdatabases "Direct link to NumberOfDatabases")

Total number of databases on the server.

### NumberOfDetachedByUserParts[​](#numberofdetachedbyuserparts "Direct link to NumberOfDetachedByUserParts")

The total number of parts detached from MergeTree tables by users with the `ALTER TABLE DETACH` query (as opposed to unexpected, broken or ignored parts). The server does not care about detached parts, and they can be removed.

### NumberOfDetachedParts[​](#numberofdetachedparts "Direct link to NumberOfDetachedParts")

The total number of parts detached from MergeTree tables. A part can be detached by a user with the `ALTER TABLE DETACH` query or by the server itself it the part is broken, unexpected or unneeded. The server does not care about detached parts, and they can be removed.

### NumberOfTables[​](#numberoftables "Direct link to NumberOfTables")

Total number of tables summed across the databases on the server, excluding the databases that cannot contain MergeTree tables. The excluded database engines are those who generate the set of tables on the fly, like `Lazy`, `MySQL`, `PostgreSQL`, `SQlite`.

### OSContextSwitches[​](#oscontextswitches "Direct link to OSContextSwitches")

The number of context switches that the system underwent on the host machine. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server.

### OSGuestNiceTime[​](#osguestnicetime "Direct link to OSGuestNiceTime")

The ratio of time spent running a virtual CPU for guest operating systems under the control of the Linux kernel, when a guest was set to a higher priority (See `man procfs`). This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. This metric is irrelevant for ClickHouse, but still exists for completeness. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSGuestNiceTimeCPU\_*N*[​](#osguestnicetimecpu_n "Direct link to osguestnicetimecpu_n")

The ratio of time spent running a virtual CPU for guest operating systems under the control of the Linux kernel, when a guest was set to a higher priority (See `man procfs`). This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. This metric is irrelevant for ClickHouse, but still exists for completeness. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSGuestNiceTimeNormalized[​](#osguestnicetimenormalized "Direct link to OSGuestNiceTimeNormalized")

The value is similar to `OSGuestNiceTime` but divided to the number of CPU cores to be measured in the [0..1] interval regardless of the number of cores. This allows you to average the values of this metric across multiple servers in a cluster even if the number of cores is non-uniform, and still get the average resource utilization metric. If specified, the Cgroup CPU quota divided by its period can be used instead of the actual number of CPU cores, and in that case the value of this metric may exceed 1 at some moments.

### OSGuestTime[​](#osguesttime "Direct link to OSGuestTime")

The ratio of time spent running a virtual CPU for guest operating systems under the control of the Linux kernel (See `man procfs`). This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. This metric is irrelevant for ClickHouse, but still exists for completeness. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSGuestTimeCPU\_*N*[​](#osguesttimecpu_n "Direct link to osguesttimecpu_n")

The ratio of time spent running a virtual CPU for guest operating systems under the control of the Linux kernel (See `man procfs`). This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. This metric is irrelevant for ClickHouse, but still exists for completeness. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSGuestTimeNormalized[​](#osguesttimenormalized "Direct link to OSGuestTimeNormalized")

The value is similar to `OSGuestTime` but divided to the number of CPU cores to be measured in the [0..1] interval regardless of the number of cores. This allows you to average the values of this metric across multiple servers in a cluster even if the number of cores is non-uniform, and still get the average resource utilization metric. If specified, the Cgroup CPU quota divided by its period can be used instead of the actual number of CPU cores, and in that case the value of this metric may exceed 1 at some moments.

### OSIOWaitTime[​](#osiowaittime "Direct link to OSIOWaitTime")

The ratio of time the CPU core was not running the code but when the OS kernel did not run any other process on this CPU as the processes were waiting for IO. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSIOWaitTimeCPU\_*N*[​](#osiowaittimecpu_n "Direct link to osiowaittimecpu_n")

The ratio of time the CPU core was not running the code but when the OS kernel did not run any other process on this CPU as the processes were waiting for IO. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSIOWaitTimeNormalized[​](#osiowaittimenormalized "Direct link to OSIOWaitTimeNormalized")

The value is similar to `OSIOWaitTime` but divided to the number of CPU cores to be measured in the [0..1] interval regardless of the number of cores. This allows you to average the values of this metric across multiple servers in a cluster even if the number of cores is non-uniform, and still get the average resource utilization metric. If specified, the Cgroup CPU quota divided by its period can be used instead of the actual number of CPU cores, and in that case the value of this metric may exceed 1 at some moments.

### OSIdleTime[​](#osidletime "Direct link to OSIdleTime")

The ratio of time the CPU core was idle (not even ready to run a process waiting for IO) from the OS kernel standpoint. This is a system-wide metric, it includes all the processes on the host machine, not just clickhouse-server. This does not include the time when the CPU was under-utilized due to the reasons internal to the CPU (memory loads, pipeline stalls, branch mispredictions, running another SMT core). The value for a single CPU core will be in the interval [0..1]. The value for all CPU cores is calculated as a sum across them [0..num cores].

### OSIdleTimeCPU\_*N*[​](#osidletimecpu_n "Direct link to osidletimecpu_n")