Кэш запросов

SELECT some_expensive_calculation(column_1, column_2)
FROM table
SETTINGS use_query_cache = true;

SELECT some_expensive_calculation(column_1, column_2)
FROM table
SETTINGS use_query_cache = true, enable_writes_to_query_cache = false;

<query_cache>
    <max_size_in_bytes>1073741824</max_size_in_bytes>
    <max_entries>1024</max_entries>
    <max_entry_size_in_bytes>1048576</max_entry_size_in_bytes>
    <max_entry_size_in_rows>30000000</max_entry_size_in_rows>
</query_cache>

<profiles>
    <default>
        <!-- The maximum cache size in bytes for user/profile 'default' -->
        <query_cache_max_size_in_bytes>10000</query_cache_max_size_in_bytes>
        <!-- The maximum number of SELECT query results stored in the cache for user/profile 'default' -->
        <query_cache_max_entries>100</query_cache_max_entries>
        <!-- Make both settings read-only so the user cannot change them -->
        <constraints>
            <query_cache_max_size_in_bytes>
                <readonly/>
            </query_cache_max_size_in_bytes>
            <query_cache_max_entries>
                <readonly/>
            </query_cache_max_entries>
        </constraints>
    </default>
</profiles>

SELECT some_expensive_calculation(column_1, column_2)
FROM table
SETTINGS use_query_cache = true, query_cache_min_query_duration = 5000;

SELECT 1 SETTINGS use_query_cache = true; -- query_cache_tag is implicitly '' (empty string)
SELECT 1 SETTINGS use_query_cache = true, query_cache_tag = 'tag 1';
SELECT 1 SETTINGS use_query_cache = true, query_cache_tag = 'tag 2';

SELECT *
FROM (SELECT number FROM system.numbers LIMIT 1000 SETTINGS use_query_cache = true)
WHERE number > 500;

SELECT *
FROM (SELECT number FROM system.numbers LIMIT 1000)
WHERE number > 500
SETTINGS use_query_cache = true, query_cache_for_subqueries = true;

SELECT *
FROM (SELECT number FROM system.numbers LIMIT 1000 SETTINGS use_query_cache = false)
WHERE number > 500
SETTINGS use_query_cache = true, query_cache_for_subqueries = true;

<filesystem_caches>
    <query_results>
        <path>query_results_cache/</path>
        <max_size>10Gi</max_size>
    </query_results>
</filesystem_caches>

SELECT some_expensive_calculation(column_1, column_2)
FROM table
SETTINGS use_query_cache = true, query_cache_on_disk_cache_name = 'query_results';