Querying Postgres Table with JSONB data

Question

I have a Table which stores data in a JSONB column.

Now, what i want to do is, query that table, and fetch records, which have specific values for a key.

This works fine:

SELECT "documents".*
FROM "documents"
WHERE (data @> '{"type": "foo"}')

But what i want to do is, fetch all the rows in the table, which have types foo OR bar.

I tried this:

SELECT "documents".*
FROM "documents"
WHERE (data @> '{"type": ["foo", "bar"]}')

But this doesn't seem to work.

I also tried this:

SELECT "documents".*
FROM "documents"
WHERE (data->'type' ?| array['foo', 'bar'])

Which works, but if I specify a key like so data->'type' it takes away the dynamicity of the query.

BTW, I am using Ruby on Rails with Postgres, so all the queries are going through ActiveRecord. This is how:

Document.where("data @> ?", query)

klin · Accepted Answer · 2016-09-29 12:43:29Z

if I specify a key like so data->'type' it takes away the dynamicity of the query.

I understand you have a gin index on the column data defined like this:

CREATE INDEX ON documents USING GIN (data);

The index works for this query:

EXPLAIN ANALYSE
SELECT "documents".*
FROM "documents"
WHERE data @> '{"type": "foo"}';

                                                          QUERY PLAN                                                          
------------------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on documents  (cost=30.32..857.00 rows=300 width=25) (actual time=0.639..0.640 rows=1 loops=1)
   Recheck Cond: (data @> '{"type": "foo"}'::jsonb)
   Heap Blocks: exact=1
   ->  Bitmap Index Scan on documents_data_idx  (cost=0.00..30.25 rows=300 width=0) (actual time=0.581..0.581 rows=1 loops=1)
         Index Cond: (data @> '{"type": "foo"}'::jsonb)
 Planning time: 7.928 ms
 Execution time: 0.841 ms

but not for this one:

EXPLAIN ANALYSE
SELECT "documents".*
FROM "documents"
WHERE (data->'type' ?| array['foo', 'bar']);

                                                QUERY PLAN                                                 
-----------------------------------------------------------------------------------------------------------
 Seq Scan on documents  (cost=0.00..6702.98 rows=300 width=25) (actual time=31.895..92.813 rows=2 loops=1)
   Filter: ((data -> 'type'::text) ?| '{foo,bar}'::text[])
   Rows Removed by Filter: 299997
 Planning time: 1.836 ms
 Execution time: 92.839 ms

Solution 1. Use the operator @> twice, the index will be used for both conditions:

EXPLAIN ANALYSE
SELECT "documents".*
FROM "documents"
WHERE data @> '{"type": "foo"}'
OR data @> '{"type": "bar"}';

                                                             QUERY PLAN                                                             
------------------------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on documents  (cost=60.80..1408.13 rows=600 width=25) (actual time=0.222..0.233 rows=2 loops=1)
   Recheck Cond: ((data @> '{"type": "foo"}'::jsonb) OR (data @> '{"type": "bar"}'::jsonb))
   Heap Blocks: exact=2
   ->  BitmapOr  (cost=60.80..60.80 rows=600 width=0) (actual time=0.204..0.204 rows=0 loops=1)
         ->  Bitmap Index Scan on documents_data_idx  (cost=0.00..30.25 rows=300 width=0) (actual time=0.144..0.144 rows=1 loops=1)
               Index Cond: (data @> '{"type": "foo"}'::jsonb)
         ->  Bitmap Index Scan on documents_data_idx  (cost=0.00..30.25 rows=300 width=0) (actual time=0.059..0.059 rows=1 loops=1)
               Index Cond: (data @> '{"type": "bar"}'::jsonb)
 Planning time: 3.170 ms
 Execution time: 0.289 ms

Solution 2. Create an additional index on (data->'type'):

CREATE INDEX ON documents USING GIN ((data->'type'));

EXPLAIN ANALYSE
SELECT "documents".*
FROM "documents"
WHERE (data->'type' ?| array['foo', 'bar']);

                                                          QUERY PLAN                                                          
------------------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on documents  (cost=30.32..857.75 rows=300 width=25) (actual time=0.056..0.067 rows=2 loops=1)
   Recheck Cond: ((data -> 'type'::text) ?| '{foo,bar}'::text[])
   Heap Blocks: exact=2
   ->  Bitmap Index Scan on documents_expr_idx  (cost=0.00..30.25 rows=300 width=0) (actual time=0.035..0.035 rows=2 loops=1)
         Index Cond: ((data -> 'type'::text) ?| '{foo,bar}'::text[])
 Planning time: 2.951 ms
 Execution time: 0.108 ms

Solution 3. In fact this is a variant of the solution 1, with a different format of the condition which may be more convenient to use by the client program:

EXPLAIN ANALYSE
SELECT "documents".*
FROM "documents"
WHERE data @> any(array['{"type": "foo"}', '{"type": "bar"}']::jsonb[]);

                                                          QUERY PLAN                                                          
------------------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on documents  (cost=60.65..1544.20 rows=600 width=26) (actual time=0.803..0.819 rows=2 loops=1)
   Recheck Cond: (data @> ANY ('{"{\"type\": \"foo\"}","{\"type\": \"bar\"}"}'::jsonb[]))
   Heap Blocks: exact=2
   ->  Bitmap Index Scan on documents_data_idx  (cost=0.00..60.50 rows=600 width=0) (actual time=0.778..0.778 rows=2 loops=1)
         Index Cond: (data @> ANY ('{"{\"type\": \"foo\"}","{\"type\": \"bar\"}"}'::jsonb[]))
 Planning time: 2.080 ms
 Execution time: 0.304 ms
(7 rows)

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