介绍PostgreSQL中的jsonb数据类型

=# COPY geodata FROM '$HOME/Downloads/allCountries.txt';
COPY 8647839
=# CREATE TABLE geodata_jsonb (data jsonb) with (fillfactor=100);
CREATE TABLE
=# CREATE TABLE geodata_json (data json) with (fillfactor=100);
CREATE TABLE
=# \timing
Timing is on.
=# INSERT INTO geodata_json SELECT row_to_json(geodata) FROM geodata;
INSERT 0 8647839
Time: 287158.457 ms
=# INSERT INTO geodata_jsonb SELECT row_to_json(geodata)::jsonb FROM geodata;
INSERT 0 8647839
Time: 425825.967 ms

=# SELECT pg_size_pretty(pg_relation_size('geodata_json'::regclass)) AS json,
     pg_size_pretty(pg_relation_size('geodata_jsonb'::regclass)) AS jsonb;
 json  | jsonb 
---------+---------
 3274 MB | 3816 MB
(1 row)

=# CREATE INDEX geodata_index ON
  geodata_json ((data-'country_code'), (data-'asciiname'));
CREATE INDEX
=# SELECT pg_size_pretty(pg_relation_size('geodata_index'::regclass))
  AS json_index;
 json_index 
------------
 310 MB
(1 row)
=# SELECT (data-'population')::int as population,
     data->'latitude' as latitude,
     data->'longitude' as longitude
  FROM geodata_json WHERE data-'country_code' = 'JP' AND
    data-'asciiname' = 'Tokyo' AND
    (data-'population')::int != 0;
 population | latitude | longitude 
------------+----------+-----------
  8336599 | 35.6895 | 139.69171
(1 row)
=# -- Explain of previous query
                            QUERY PLAN                            
-------------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on geodata_json (cost=6.78..865.24 rows=215 width=32)
  Recheck Cond: (((data - 'country_code'::text) = 'JP'::text) AND ((data - 'asciiname'::text) = 'Tokyo'::text))
  Filter: (((data - 'population'::text))::integer <> 0)
  -> Bitmap Index Scan on geodata_index (cost=0.00..6.72 rows=216 width=0)
     Index Cond: (((data - 'country_code'::text) = 'JP'::text) AND ((data - 'asciiname'::text) = 'Tokyo'::text))
 Planning time: 0.172 ms
(6 rows)

=# CREATE INDEX geodata_gin ON geodata_jsonb
   USING GIN (data jsonb_hash_ops);
CREATE INDEX
=# SELECT (data-'population')::int as population,
   data->'latitude' as latitude,
   data->'longitude' as longitude
  FROM geodata_jsonb WHERE data @> '{"country_code": "JP", "asciiname": "Tokyo"}' AND
    (data-'population')::int != 0;
 population | latitude | longitude 
------------+----------+-----------
  8336599 | 35.6895 | 139.69171
(1 row)
 =# SELECT pg_size_pretty(pg_relation_size('geodata_gin'::regclass)) AS jsonb_gin;
 jsonb_gin
-----------
 1519 MB
(1 row)
=# -- EXPLAIN of previous query
                   QUERY PLAN                   
-------------------------------------------------------------------------------------
 Bitmap Heap Scan on geodata_jsonb (cost=131.01..31317.76 rows=8605 width=418)
  Recheck Cond: (data @> '{"asciiname": "Tokyo", "country_code": "JP"}'::jsonb)
  Filter: (((data - 'population'::text))::integer <> 0)
  -> Bitmap Index Scan on geodata_gin (cost=0.00..128.86 rows=8648 width=0)
     Index Cond: (data @> '{"asciiname": "Tokyo", "country_code": "JP"}'::jsonb)
 Planning time: 0.134 ms