问题
Lets say I have a blog database where posts table stores tags in hstore.
Keys represent tag ids and values are tag names.
ex : 1=>'Test', 56=>'SQL', 42=>'Java'
I want to have optimized selects on posts with tag filter. How and what type of select should I create on tags column in order to optimize this query
SELECT * FROM posts WHERE tags?'4'
The issue is that I don't have predictable key names on order to create index based on their value.
Would it be a good solution to create gist index on column?
And how I can make it to treat key as an integer?
回答1:
A GIN index is probably the better choice:
CREATE INDEX posts_tags_idx ON posts USING gin (tags);
That works for all keys.
You could further optimize the index if queries are only for a specific key with a partial index:
CREATE INDEX posts_tags_idx ON posts USING gin (tags -> '4')) WHERE x ? '4';
hstore ? text ... does hstore contain key?
But that doesn't seem to be an option for you.
hstore stores text only, not integer. Per documentation:
Keys and values are simply text strings.
来源：https://stackoverflow.com/questions/22183372/index-in-hstore-with-no-predictable-key