EXPLAIN PLAN indexes = 1 (docs) shows the result of primary and skip index analysis for a SELECT query.

Previously, ClickHouse

• did primary key analysis
• then did skip index analysis,
• then checked the query condition cache ,
• finally scanned the "surviving" ranges of the column.

As per #81526 (first appeared in ClickHouse v25.9), skip indexes are analyzed during scan. As a result, EXPLAIN PLAN indexes = 1 started to show incorrect output. Users need to run the query with SETTINGS use_skip_indexes_on_data_read = 0 to fix that.

Further, #82380 (first appears in ClickHouse v25.10) moves query condition cache probing before primary and skip index analysis. Again, EXPLAIN PLAN indexes = 1 started to show incorrect output. Users need to run the query with SETTINGS use_query_condition_cache = 0 to fix that.

We should

• set use_skip_indexes_on_data_read = 0, use_query_condition_cache = 0 internally automatically when running EXPLAIN PLAN indexes = 1,
• revert changes a la SET use_query_condition_cache = 0; done to our .sql and .sh tests in above two PRs,
• revert docs fix Docs: Add note for EXPLAIN PLAN indexes = 1 that recommends use_query_condition_cache = 1 #88462.