PolarDB:View DDL execution speed and build progress for IMCIs

Monitor build progress

Run the following query to see all in-progress IMCI build tasks:

SELECT
  SCHEMA_NAME,
  TABLE_NAME,
  STATUS,
  SCANNED_ROWS,
  APPROXIMATE_ROWS,
  AVG_SPEED,
  SPEED_LAST_SECOND,
  ESTIMATE_SECOND
FROM INFORMATION_SCHEMA.IMCI_ASYNC_DDL_STATS;

To monitor a specific table, add a WHERE clause:

SELECT * FROM INFORMATION_SCHEMA.IMCI_ASYNC_DDL_STATS
WHERE SCHEMA_NAME = '<your_database>' AND TABLE_NAME = '<your_table>';

Keep querying IMCI_ASYNC_DDL_STATS until the row disappears, then confirm the final state in IMCI_INDEXES. The row is cleared within 5–10 minutes after the task completes.

IMCI_ASYNC_DDL_STATS schema

The schema depends on your PolarDB for MySQL Enterprise Edition cluster version.

CREATE TABLE: CREATE TEMPORARY TABLE `IMCI_ASYNC_DDL_STATS` (
  `SCHEMA_NAME` varchar(193) NOT NULL DEFAULT '', -- The database name.
  `TABLE_NAME` varchar(193) NOT NULL DEFAULT '', -- The table name.
  `CREATED_AT` varchar(64) NOT NULL DEFAULT '', -- The timestamp when the task was created.
  `STARTED_AT` varchar(64) NOT NULL DEFAULT '', -- The timestamp when the task starts.
  `FINISHED_AT` varchar(64) NOT NULL DEFAULT '', -- The timestamp when the task ends.
  `STATUS` varchar(128) NOT NULL DEFAULT '', -- The task status.
  `APPROXIMATE_ROWS` bigint(8) NOT NULL DEFAULT '0', -- The estimated number of rows for baseline data.
  `SCANNED_ROWS` bigint(8) NOT NULL DEFAULT '0', -- The number of scanned rows. The actual number may exceed the estimate.
  `AVG_SPEED` int(4) NOT NULL DEFAULT '0', -- The average speed of the task. Unit: rows per second.
  `SPEED_LAST_SECOND` int(4) NOT NULL DEFAULT '0', -- The scan speed in the last second. Unit: rows per second.
  `ESTIMATE_SECOND` bigint(8) NOT NULL DEFAULT '0' -- The estimated remaining time. Unit: seconds. If write throttling is triggered, this value becomes 9223372036854775807 (INT64 MAX).
) ENGINE=MEMORY DEFAULT CHARSET=utf8

Create Table: CREATE TEMPORARY TABLE `IMCI_ASYNC_DDL_STATS` (
  `SCHEMA_NAME` varchar(193) NOT NULL DEFAULT '', -- The database name.
  `TABLE_NAME` varchar(193) NOT NULL DEFAULT '', -- The table name.
  `CREATED_AT` varchar(64) NOT NULL DEFAULT '', -- The timestamp when the task was created.
  `STARTED_AT` varchar(64) NOT NULL DEFAULT '', -- The timestamp when the task starts.
  `FINISHED_AT` varchar(64) NOT NULL DEFAULT '', -- The timestamp when the task ends.
  `STATUS` varchar(128) NOT NULL DEFAULT '', -- The task status.
  `APPROXIMATE_ROWS` bigint(8) NOT NULL DEFAULT '0', -- The estimated number of rows for baseline data.
  `SCANNED_ROWS` varchar(128) NOT NULL DEFAULT '', -- The number and percentage of scanned rows. The actual number may exceed the estimate.
  `SCAN_SECOND` bigint(8) NOT NULL DEFAULT '0', -- The elapsed time for the scan phase. Unit: seconds.
  `SORT_ROUNDS` bigint(8) NOT NULL DEFAULT '0', -- The number of sorting rounds. Applies only when sort keys are involved.
  `SORT_SECOND` bigint(8) NOT NULL DEFAULT '0', -- The elapsed time for the sort phase. Unit: seconds. Applies only when sort keys are involved.
  `BUILD_ROWS` varchar(128) NOT NULL DEFAULT '', -- The number and percentage of rows written after sorting. Applies only when sort keys are involved.
  `BUILD_SECOND` bigint(8) NOT NULL DEFAULT '0', -- The elapsed time for writing data after sorting. Unit: seconds. Applies only when sort keys are involved.
  `AVG_SPEED` int(4) NOT NULL DEFAULT '0', -- The average speed of the task. Unit: rows per second.
  `SPEED_LAST_SECOND` int(4) NOT NULL DEFAULT '0', -- The speed in the last second. Unit: rows per second. Applies to the scanning and sorting phases.
  `ESTIMATE_SECOND` bigint(8) NOT NULL DEFAULT '0' -- The estimated remaining time. Unit: seconds. Applies to the scanning and sorting phases. If write throttling is triggered, this value becomes 9223372036854775807 (INT64 MAX).
) ENGINE=MEMORY DEFAULT CHARSET=utf8

Usage notes

• SPEED_LAST_SECOND fluctuates with system resource usage and concurrent tasks.

• ESTIMATE_SECOND is calculated by dividing remaining rows by SPEED_LAST_SECOND. It fluctuates accordingly. When write throttling sets the last-second speed to 0, ESTIMATE_SECOND becomes 9223372036854775807.