Information Schema OPTIMIZER_TRACE Table

MariaDB starting with 10.4.3

Optimizer Trace was introduced in MariaDB 10.4.3.

Description

The Information Schema OPTIMIZER_TRACE table contains Optimizer Trace information.

It contains the following columns:

Column	Description
`QUERY`	Displays the query that was asked to be traced.
`TRACE`	A JSON document displaying the stats we collected when the query was run.
`MISSING_BYTES_BEYOND_MAX_MEM_SIZE`	For huge trace, where the trace is truncated due to the optimizer_trace_max_mem_size limit being reached, displays the bytes that are missing in the trace
`NSUFFICENT_PRIVILEGES`	Set to 1 if the user running the trace does not have the privileges to see the trace.

Structure:

SHOW CREATE TABLE INFORMATION_SCHEMA.OPTIMIZER_TRACE \G
*************************** 1. row ***************************
       Table: OPTIMIZER_TRACE
Create Table: CREATE TEMPORARY TABLE `OPTIMIZER_TRACE` (
  `QUERY` longtext NOT NULL DEFAULT '',
  `TRACE` longtext NOT NULL DEFAULT '',
  `MISSING_BYTES_BEYOND_MAX_MEM_SIZE` int(20) NOT NULL DEFAULT 0,
  `INSUFFICIENT_PRIVILEGES` tinyint(1) NOT NULL DEFAULT 0
) ENGINE=Aria DEFAULT CHARSET=utf8 PAGE_CHECKSUM=0

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https://mariadb.com/kb/en/information-schema-optimizer_trace-table/