issues: 830567275

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association pull_request body repo type active_lock_reason performed_via_github_app reactions draft state_reason
830567275 MDU6SXNzdWU4MzA1NjcyNzU= 1259 Research using CTEs for faster facet counts 9599 open 0     5 2021-03-12T22:19:49Z 2021-03-21T22:55:31Z   OWNER  

https://www.sqlite.org/changes.html#version_3_35_0

Add support for the MATERIALIZED and NOT MATERIALIZED hints when specifying common table expressions. The default behavior was formerly NOT MATERIALIZED, but is now changed to MATERIALIZED for CTEs that are used more than once.

If a CTE creates a table that is used multiple time in that query, SQLite will now default to creating a materialized table for the duration of that query.

This could be a big performance boost when applying faceting multiple times against the same query. Consider this example query: sql WITH data as ( select * from [global-power-plants] ), country_long as (select 'country_long' as col, country_long as value, count(*) as c from data group by country_long order by c desc limit 10 ), primary_fuel as ( select 'primary_fuel' as col, primary_fuel as value, count(*) as c from data group by primary_fuel order by c desc limit 10 ) select * from primary_fuel union select * from country_long order by col, c desc https://global-power-plants.datasettes.com/global-power-plants?sql=WITH+data+as+%28%0D%0A++select%0D%0A++++%0D%0A++from%0D%0A++++%5Bglobal-power-plants%5D%0D%0A%29%2C%0D%0Acountry_long+as+%28select+%0D%0A++%27country_long%27+as+col%2C+country_long+as+value%2C+count%28%29+as+c+from+data+group+by+country_long%0D%0A++order+by+c+desc+limit+10%0D%0A%29%2C%0D%0Aprimary_fuel+as+%28%0D%0Aselect%0D%0A++%27primary_fuel%27+as+col%2C+primary_fuel+as+value%2C+count%28%29+as+c+from+data+group+by+primary_fuel%0D%0A++order+by+c+desc+limit+10%0D%0A%29%0D%0Aselect++from+primary_fuel+union+select+*+from+country_long+order+by+col%2C+c+desc

Outputs:

col | value | c -- | -- | -- country_long | United States of America | 8688 country_long | China | 4235 country_long | United Kingdom | 2603 country_long | Brazil | 2360 country_long | France | 2155 country_long | India | 1590 country_long | Germany | 1309 country_long | Canada | 1159 country_long | Spain | 829 country_long | Russia | 545 primary_fuel | Solar | 9662 primary_fuel | Hydro | 7155 primary_fuel | Wind | 5188 primary_fuel | Gas | 3922 primary_fuel | Coal | 2390 primary_fuel | Oil | 2290 primary_fuel | Biomass | 1396 primary_fuel | Waste | 1087 primary_fuel | Nuclear | 198 primary_fuel | Geothermal | 189

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