update

tidb-performance-tuning-config.md

@@ -59,7 +59,7 @@ The following table outlines the impact of specific system variable configuratio
 | [`tidb_enable_instance_plan_cache`](/system-variables.md#tidb_enable_instance_plan_cache-new-in-v840) and [`tidb_instance_plan_cache_max_size`](/system-variables.md#tidb_instance_plan_cache_max_size-new-in-v840)| Use instance-level plan cache instead of session-level caching. This significantly improves performance for workloads with high connection counts or frequent prepared statement usage. | This is an experimental feature. Test in non-production environments first and monitor memory usage as the plan cache size increases. |
 | [`tidb_enable_non_prepared_plan_cache`](/system-variables.md#tidb_enable_non_prepared_plan_cache)| Enable the [Non-prepared plan cache](/sql-non-prepared-plan-cache.md) feature to reduce compile costs for applications that do not use prepared statements. | N/A |
 | [`tidb_ignore_prepared_cache_close_stmt`](/system-variables.md#tidb_ignore_prepared_cache_close_stmt-new-in-v600)| Cache plans for applications that use prepared statements but close the plan after each execution. | N/A |
-| [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830)| Collect statistics for all the columns to avoid bad execution plan causing by missing statistics. | This can cause more resource usage for the analyze job compared to the default value |
+| [`tidb_analyze_column_options`](/system-variables.md#tidb_analyze_column_options-new-in-v830)| Collect statistics for all the columns to avoid suboptimal execution plans causing by missing column statistics, since the defalut behaviour will only collect statistics for [predicate columns](/statistics.md#collect-statistics-on-some-columns). | This can cause more resource usage for the analyze job compared to the default value |
 | [`tidb_enable_inl_join_inner_multi_pattern`](/system-variables.md#tidb_enable_inl_join_inner_multi_pattern-new-in-v700)| Enable Index Join support when the inner table has `Selection` or `Projection` operators on it. | N/A | 
 | [`tidb_opt_derive_topn`](/system-variables.md#tidb_opt_derive_topn-new-in-v700)| Enable the optimization rule of [Deriving TopN or Limit from window functions](/derive-topn-from-window.md). | This is limited to the `ROW_NUMBER()` window function. | 
 | [`tidb_runtime_filter_mode`](/system-variables.md#tidb_runtime_filter_mode-new-in-v720)| Enable [Runtime Filter](/runtime-filter.md#runtime-filter-mode) in the local mode to improve hash join efficiency. | The variable is introduced in v7.2.0 and is disabled by default for safety. |