iterators_*

The iterators_* tables store information about query plan iterators and their metrics. A query iterator refers to a node or operation in a query plan. For example, a sequential scan operation on a table may be one type of iterator in a particular query plan.

The tmid, ssid and ccnt columns are the composite key that uniquely identifies a particular query. These columns can be used to join with the queries_* data tables.

There are three iterator tables, all having the same columns:

iterators_now is an external table whose data files are stored in $MASTER_DATA_DIRECTORY/gpperfmon/data. Current query plan iterator data is stored in iterators_now during the period between data collection from the Command Center agents and automatic commitment to the iterators_history table.
iterators_tail is an external table whose data files are stored in $MASTER_DATA_DIRECTORY/gpperfmon/data. This is a transitional table for query plan iterator data that has been cleared from iterators_now but has not yet been committed to iterators_history. It typically only contains a few minutes worth of data.
iterators_history is a regular table that stores historical query plan iterator data. It is pre-partitioned into monthly partitions. Partitions are automatically added in two month increments as needed. Administrators must drop old partitions for the months that are no longer needed.

See also the iterator_rollup views for summary metrics of the query plan iterator data.

Column	Type	Description
`ctime`	timestamp	Time this row was created.
`tmid`	int	A time identifier for a particular query. All iterator records associated with the query will have the same tmid.
`ssid`	int	The session id as shown by the `gp_session_id` parameter. All iterator records associated with the query will have the same `ssid`.
`ccnt`	int	The command number within this session as shown by `gp_command_count` parameter. All iterator records associated with the query will have the same `ccnt`.
`segid`	int	The segment ID (`dbid` from `gp_segment_configuration`).
`pid`	int	The postgres process ID for this iterator.
`nid`	int	The query plan node ID from the Greenplum slice plan.
`pnid`	int	The parent query plan node ID from the Greenplum slice plan.
`hostname`	varchar(64)	Segment hostname.
`ntype`	varchar(64)	The iterator operation type. Possible values are listed in [Iterator Metrics](db-iterator-metrics.html).
`nstatus`	varchar(64)	The status of this iterator. Possible values are: Initialize, Executing and Finished.
`tstart`	timestamp	Start time for the iterator.
`tduration`	int	Duration of the execution.
`pmemsize`	bigint	Maximum work memory allocated by the Greenplum planner to this iterator’s query process.
`memsize`	bigint	OS memory allocated to this iterator’s process.
`memresid`	bigint	Resident memory allocated to this iterator’s process (as opposed to shared memory).
`memshare`	bigint	Shared memory allocated to this iterator’s process.
`cpu_elapsed`	bigint	Total CPU usage of the process executing the iterator.
`cpu_currpct`	float	The percentage of CPU currently being utilized by this iterator process. This value is always zero for historical (completed) iterators.
`rowsout`	bigint	The actual number of rows output by the iterator.
`rowsout_est`	bigint	The query planner’s estimate of rows output by the iterator.
`m0_name`	varchar(64)	Each operation in a query plan (ntype) has metrics associated with it. For all operations, this metric name is `Rows In`.
`m0_unit`	varchar(64)	The unit of measure for this metric. For all operations (`ntype`), this unit of measure is `Rows`.
`m0_val`	bigint	The value of this metric.
`m0_est`	bigint	The estimated value of this metric.
`m1_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m1_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m1_val`	bigint	The value of this metric.
`m1_est`	bigint	The estimated value of this metric.
`m2_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m2_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m2_val`	bigint	The value of this metric.
`m2_est`	bigint	The estimated value of this metric.
`m3_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m3_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m3_val`	bigint	The value of this metric.
`m3_est`	bigint	The estimated value of this metric.
`m4_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m4_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m4_val`	bigint	The value of this metric.
`m4_est`	bigint	The estimated value of this metric.
`m5_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m5_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m5_val`	bigint	The value of this metric.
`m5_est`	bigint	The estimated value of this metric.
`m6_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m6_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m6_val`	bigint	The value of this metric.
`m6_est`	bigint	The estimated value of this metric.
`m7_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m7_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m7_val`	bigint	The value of this metric.
`m7_est`	bigint	The estimated value of this metric.
`m8_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m8_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m8_val`	bigint	The actual value of this metric.
`m8_est`	bigint	The estimated value of this metric.
`m9_name`	varchar(64)	Each operation in a query plan (`ntype`) has metrics associated with it. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m9_unit`	varchar(64)	The unit of measure for this metric. See [Iterator Metrics](db-iterator-metrics.html) for a complete list of iterator attributes and their corresponding units.
`m9_val`	bigint	The actual value of this metric.
`m9_est`	bigint	The estimated value of this metric.
`m10_name` - `m15_name`	varchar(64)	The iterator name (`ntype`) associated with this metric. Metrics `m10` through `m15` are currently not used.
`m10_unit` - `m15_unit`	varchar(64)	The unit of measure for this metric. Metrics `m10` through`m15` are currently not used.
`m10_value` - `m15_value`	bigint	The actual value of this metric. Metrics `m10` through `m15` are currently not used.
`m10_est` - `m15_est`	bigint	The estimated value of this metric. Metrics `m10` through `m15` are currently not used.
`t0_name`	varchar(64)	This column is a label for `t0_val`. Its value is always `Name`.
`t0_val`	varchar(128)	The name of the relation being scanned by an iterator. This metric is collected only for iterators that perform scan operations such as a sequential scan or function scan.