[Yandex Cloud documentation](../../index.md) > [Yandex MPP Analytics for PostgreSQL](../index.md) > [Concepts](overview.md) > Command center settings # Yandex MPP Analytics for PostgreSQL Command Center parameters This section describes the session and query parameters available in [Yandex MPP Analytics for PostgreSQL Command Center](command-center.md). ## Session {#cc-session} **Resources**: * **CPU time**: Time used by CPU resources to process queries. * **Peak memory**: Maximum memory used to process queries. * **Spill**: Total size of the files generated and spilled to disk while executing the query. * **Disk R**: Number of bytes read from disk while executing the query. * **Disk W**: Number of bytes written to disk while executing the query. * **Packets recv**: Number of packets received via `interconnect`. * **Packets sent**: Number of packets sent via `interconnect`. **Session info**: * **User**: Username. * **Database**: Database name. * **Status changed**: Date and time of the most recent status change. * **Start time**: Session start date and time. * **Application**: Connected client’s app name. * **Client host**: Connected client’s host name. * **Process ID**: Current session ID. * **Client address**: Connected client’s IP address. * **Client port**: Number of the port the client uses for the connection. * **Transaction start time**: Current transaction’s start date and time. * **Waiting**: This parameter defines whether the session waits for blocking events to complete. * **Transaction horizon**: Earliest transaction ID. * **OID resource group**: [Resource group](resource-groups.md) object ID. * **Resource group**: Current resource group name. **Queries**: * **Key of running query**: [Query key](command-center.md#statement-key). * **Query text**: Text of the query being executed. * **Start time**: Date and time when the query started executing. * **Query state**: Status of the query being executed. * **Plan ID**: Query execution plan ID. **Other resources**: * **CPU user time**: Time used by CPU resources to run program instructions. * **CPU kernel time**: Time used by CPU resources to process system calls. * **Resident set size**: Memory used to execute session queries, in bytes. * **Virtual memory size**: Memory allocated to the session. * **Chars read**: Number of read characters. * **Chars written**: Number of written characters. * **Read syscalls**: Number of read operations. * **Write syscalls**: Number of write operations. * **Cancelled write bytes**: Size of data dropped due to a canceled write. * **Packets sent**: Number of packets sent via `interconnect`. * **Packets recv**: Number of packets received via `interconnect`. **Number of rows and optimizer rating**: * **Cycles count**: Number of plan node calls. * **First tuple time**: Time spent processing the first row, in seconds. * **Startup time**: Time spent starting the operator, in seconds. * **Total time**: Total time spent processing rows. **Number of buffer accesses and other DB counters**: * **Shared buffer hits**: Number of shared memory blocks fetched from the buffer. * **Shared disk blocks read**: Number of shared memory blocks read from disk as they were missing in the buffer. * **Shared blocks dirtied**: Number of shared memory blocks that were modified and now require writing to disk. * **Shared disk blocks written**: Number of shared memory blocks written to disk. * **Local buffer hits**: Number of local blocks fetched from the buffer. * **Local disk blocks read**: Number of local blocks read from disk as they were missing in the buffer. * **Local disk blocks written**: Number of local blocks written to disk. * **Temp blocks read**: Number of temporary file blocks read from disk. * **Temp blocks written**: Number of temporary file blocks written to disk. * **Time spent reading blocks**: Time spent reading blocks. * **Time spent writing blocks**: Time spent writing blocks. * **Spill file count**: Number of spill files. * **Planning and resource waiting time**: Time spent waiting for resources and planning. ## Query {#cc-query} **Resources**: * **CPU time**: Time used by CPU resources to process queries. * **Peak memory**: Maximum memory used to process queries. * **Spill**: Total size of the files generated and spilled to disk while executing the query. * **Disk R**: Number of bytes read from disk while executing the query. * **Disk W**: Number of bytes written to disk while executing the query. * **Packets recv**: Number of packets received via `interconnect`. * **Packets sent**: Number of packets sent via `interconnect`. * **Skew**: Data skew (non-uniform distribution across segments). **Query info**: * **Query key**: Unique attribute assigned to the query during its execution. * **Start time**: Query execution start date and time. * **End time**: Query execution end date and time. * **Optimizer**: [Query optimizer](https://techdocs.broadcom.com/us/en/vmware-tanzu/data-solutions/tanzu-greenplum/7/greenplum-database/admin_guide-query-topics-optimizer-hints.html). * **Min time**: Minimum query execution time. * **Max time**: Maximum query execution time. * **User**: Username. * **Database**: Database name. * **Query ID**: [Non-unique hash](command-center.md#statement-id) generated from the query text. **Other resources**: * **CPU user time**: Time used by CPU resources to run program instructions. * **CPU kernel time**: Time used by CPU resources to process system calls. * **Resident Set Size**: Memory used to execute the query, in bytes. * **Virtual Memory Size**: Memory allocated to execute the query. * **Chars read**: Number of read characters. * **Chars written**: Number of written characters. * **Read syscalls**: Number of read operations. * **Write syscalls**: Number of write operations. * **Cancelled write bytes**: Size of data dropped due to a canceled write. * **Packets sent**: Number of packets sent via `interconnect`. * **Packets recv**: Number of packets received via `interconnect`. **Number of rows and optimizer rating**: * **Cycles count**: Number of plan node calls. * **First tuple time**: Time spent processing the first row, in seconds. * **Startup time**: Time spent starting the operator, in seconds. * **Total time**: Total time spent processing rows. **Number of buffer accesses and other DB counters**: * **Shared buffer hits**: Number of shared memory blocks fetched from the buffer. * **Shared disk blocks read**: Number of shared memory blocks read from disk as they were missing in the buffer. * **Shared blocks dirtied**: Number of shared memory blocks that were modified and now require writing to disk. * **Shared disk blocks written**: Number of shared memory blocks written to disk. * **Local buffer hits**: Number of local blocks fetched from the buffer. * **Local disk blocks read**: Number of local blocks read from disk as they were missing in the buffer. * **Local blocks dirtied**: Number of local blocks that were modified and now require writing to disk. * **Local disk blocks written**: Number of local blocks written to disk. * **Temp blocks read**: Number of temporary file blocks read from disk. * **Temp blocks written**: Number of temporary file blocks written to disk. * **Time spent reading blocks**: Time spent reading blocks. * **Time spent writing blocks**: Time spent writing blocks. * **Spill file count**: Number of spill files. * **Planning and resource waiting time**: Time spent waiting for resources and planning. ## Interconnect network metrics {#cc-interconnect} * **Interconnect active connections num**: Maximum number of active outbound connections registered. * **Interconnect buffer counting time**: Monotonically increasing counter of buffer availability checks before sending packets. It increases with each successful outbound connection. * **Interconnect buffer counting time**: Monotonically increasing counter of outbound queue size checks. It increases with every processed connection. * **Interconnect CRC errors**: Monotonically increasing counter of packets that failed [checksum validation](https://en.wikipedia.org/wiki/Cyclic_redundancy_check). It applies if `gp_interconnect_full_crc` is enabled. * **Interconnect disordered pkt num**: Monotonically increasing counter of out-of-order packets. It increases if at least one of these conditions is met: * The sequence number of the inbound packet does not match the expected value. * The inbound packet queue overflowed and the packet was dropped. * **Interconnect duplicated pkt num**: Monotonically increasing counter of duplicate packets. It increases when the sequence number of the inbound packet is lower than the highest sequence number of processed packets. * **Interconnect mismatch num**: Monotonically increasing counter of mismatched packets. These packets pertain to the previous query or the current one but are not yet ready for processing. * **Interconnect recv ack num**: Monotonically increasing counter of acknowledgments for inbound packets. * **Interconnect recv pkt num**: Monotonically increasing counter of processed inbound packets. * **Interconnect recv queue size counting time**: Monotonically increasing counter of inbound queue size checks. It increases with every processed connection. * **Interconnect retransmits**: Monotonically increasing counter of retransmitted packets. Retransmission applies to out-of-order and outdated packets. * **Interconnect snd pkt num**: Monotonically increasing counter of sent packets. * **Interconnect startup cached pkt num**: Monotonically increasing counter of cached packets received but not yet ready for processing. * **Interconnect status query msg num**: Monotonically increasing counter of transmitted status packets. These packets are used to check the connection health if no packet transmission acknowledgments are received for a while. * **Interconnect total buffers**: Minimum number of available buffers registered before sending packets. * **Interconnect total capacity**: Maximum size of the outbound queue, in packets. * **Interconnect total recv queue size**: Maximum size of the inbound queue, in packets. Learn more about `interconnect` [here](https://techdocs.broadcom.com/us/en/vmware-tanzu/data-solutions/tanzu-greenplum/6/greenplum-database/admin_guide-intro-arch_overview.html#arch_interconnect).