html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,issue,performed_via_github_app
https://github.com/simonw/datasette/issues/321#issuecomment-398973176,https://api.github.com/repos/simonw/datasette/issues/321,398973176,MDEyOklzc3VlQ29tbWVudDM5ODk3MzE3Ng==,9599,2018-06-21T04:34:11Z,2018-06-21T16:53:57Z,OWNER,"This is a little bit fiddly, but it's possible to do it using SQLite string concatenation. Here's an example:
```
select * from facetable
where neighborhood like ""%"" || :text || ""%"";
```
Try it here: https://latest.datasette.io/fixtures-35b6eb6?sql=select+*+from+facetable+where+neighborhood+like+%22%25%22+%7C%7C+%3Atext+%7C%7C+%22%25%22%3B&text=town
","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",334190959,
https://github.com/simonw/datasette/issues/321#issuecomment-399171239,https://api.github.com/repos/simonw/datasette/issues/321,399171239,MDEyOklzc3VlQ29tbWVudDM5OTE3MTIzOQ==,9599,2018-06-21T16:51:08Z,2018-06-21T16:51:29Z,OWNER,"I may have misunderstood your problem here.
I understood that the problem is that when using the `""%"" || :text || ""%""` construct the first hit to that page (with an empty string for `:text`) results in a `where neighborhood like ""%%""` query which is slow because it matches every row in the database.
My fix was to add this to the where clause:
where :text != '' and ...
Which means that when you first load the page the where fails to match any rows and you get no results (and hopefully instant loading times assuming SQLite is smart enough to optimize this away). That's why you don't see any rows returned on this page: https://latest.datasette.io/fixtures-cafd088?sql=select+neighborhood%2C+facet_cities.name%2C+state%0D%0Afrom+facetable%0D%0A++++join+facet_cities+on+facetable.city_id+%3D+facet_cities.id%0D%0Awhere+%3Atext+%21%3D+%22%22+and+neighborhood+like+%27%25%27+%7C%7C+%3Atext+%7C%7C+%27%25%27%0D%0Aorder+by+neighborhood%3B","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",334190959,
https://github.com/simonw/datasette/issues/321#issuecomment-399126228,https://api.github.com/repos/simonw/datasette/issues/321,399126228,MDEyOklzc3VlQ29tbWVudDM5OTEyNjIyOA==,9599,2018-06-21T14:36:40Z,2018-06-21T14:36:53Z,OWNER,"This seems to fix that:
```
select neighborhood, facet_cities.name, state
from facetable
join facet_cities on facetable.city_id = facet_cities.id
where :text != '' and neighborhood like '%' || :text || '%'
order by neighborhood;
```
Compare this (with empty string): https://latest.datasette.io/fixtures-cafd088?sql=select+neighborhood%2C+facet_cities.name%2C+state%0D%0Afrom+facetable%0D%0A++++join+facet_cities+on+facetable.city_id+%3D+facet_cities.id%0D%0Awhere+%3Atext+%21%3D+%22%22+and+neighborhood+like+%27%25%27+%7C%7C+%3Atext+%7C%7C+%27%25%27%0D%0Aorder+by+neighborhood%3B
To this: https://latest.datasette.io/fixtures-cafd088?sql=select+neighborhood%2C+facet_cities.name%2C+state%0D%0Afrom+facetable%0D%0A++++join+facet_cities+on+facetable.city_id+%3D+facet_cities.id%0D%0Awhere+%3Atext+%21%3D+%22%22+and+neighborhood+like+%27%25%27+%7C%7C+%3Atext+%7C%7C+%27%25%27%0D%0Aorder+by+neighborhood%3B&text=town","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",334190959,
https://github.com/simonw/datasette/issues/321#issuecomment-398976488,https://api.github.com/repos/simonw/datasette/issues/321,398976488,MDEyOklzc3VlQ29tbWVudDM5ODk3NjQ4OA==,9599,2018-06-21T04:59:33Z,2018-06-21T06:11:02Z,OWNER,"I've added this to the unit tests and the documentation.
Docs: http://datasette.readthedocs.io/en/latest/sql_queries.html#canned-queries
Canned query demo: https://latest.datasette.io/fixtures/neighborhood_search?text=town
New unit test:
https://github.com/simonw/datasette/blob/3683a6b626b2e79f4dc9600d45853ca4ae8de11a/tests/test_api.py#L333-L344
https://github.com/simonw/datasette/blob/3683a6b626b2e79f4dc9600d45853ca4ae8de11a/tests/fixtures.py#L145-L153","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",334190959,