Set up docs MCPThese settings are available in system.settings and are autogenerated from the ClickHouse snapshot.
optimize_rewrite_aggregate_function_with_if
Rewrite aggregate functions with if expression as argument when logically equivalent.
For example, avg(if(cond, col, null)) can be rewritten to avgOrNullIf(cond, col). It may improve performance.
optimize_rewrite_array_exists_to_has
Rewrite arrayExists() functions to has() when logically equivalent. For example, arrayExists(x -> x = 1, arr) can be rewritten to has(arr, 1)
optimize_rewrite_has_to_in
Rewrite has functions to IN when the first argument is a constant array. For example, has([1, 2, 3], x) can be rewritten to x IN [1, 2, 3] for better performance with constant arrays
optimize_rewrite_like_perfect_affix
Rewrite LIKE expressions with perfect prefix or suffix (e.g. col LIKE 'ClickHouse%') to startsWith or endsWith functions (e.g. startsWith(col, 'ClickHouse')).
optimize_rewrite_regexp_functions
Rewrite regular expression related functions into simpler and more efficient forms
optimize_rewrite_sum_if_to_count_if
Rewrite sumIf() and sum(if()) function countIf() function when logically equivalent