user5144 Published in September 20, 2018, 12:45 pm
I have never used GIN indexing before and I am trying to understand how it works.
I have a static table with 4million rows, which I need to run SELECT queries with WHERE clauses.
Right now my table has a B-Tree index on the column "name" which is used in the where clause.
I have read that doing a full text search using a GIN index can greatly improve the speed. I have read the tutorial here and right now I am not sure if this is something I can use when I have only one table.
Does full text search works in case of multiple tables that we want to join?
I understand that the GIN Indexing works on a tsvector column. This is what I have done till now:
I have altered my table and added one more column: tsv:
ALTER TABLE my_table ADD COLUMN tsv tsvector;
I createad a GIN index on my ts_vector column:
CREATE INDEX tsv_idx ON my_table USING gin(to_tsvector('english', name));
And I have updated the column:
UPDATE my_table SET tsv = to_tsvector(name)
Are the above correct? So now if I want to run the following query:
SELECT clm1, clmn2 FROM my_table WHERE name LIKE 'Ath%' ORDER BY 1
how can I do it using the GIN index?
I tried this:
SELECT clm1, clmn2 FROM my_table WHERE tvs LIKE 'Ath%' ORDER BY 1
But I get an error:
ERROR: operator does not exist: tsvector ~~ unknown
What am I missing here? What is the correct use of GIN? And can I apply full text search on a single table?