tencent cloud

CREATE TABLE sensor_log (
 sensor_log_id SERIAL PRIMARY KEY,
 location VARCHAR NOT NULL,
 reading BIGINT NOT NULL,
 reading_date TIMESTAMP NOT NULL
);
CREATE INDEX idx_sensor_log_location ON sensor_log (location);
CREATE INDEX idx_sensor_log_date ON sensor_log (reading_date);
insert into sensor_log(location,reading,reading_date) values('38c-
1401',293857,current_timestamp);
insert into sensor_log(location,reading,reading_date) values('38c-
1402',293858,current_timestamp);
insert into sensor_log(location,reading,reading_date) values('34c-
1401',293859,current_timestamp);
insert into sensor_log(location,reading,reading_date) values('18c-
1401',2938510,current_timestamp);

psql -U root -p 5432 -h 10.0.4.8 -d hehe -c \\COPY sensor_log 
(sensor_log_id,location, reading,reading_date) TO '/mnt/xxx/sensor_log.csv' WITH 
csv;

psql -U root -p 5432 -h 10.0.4.8 -d hehe -c '\\COPY (select * from sensor_log 
where location='18c-1401') TO '/mnt/pgstorage/sensor_log.csv' WITH csv;'

CREATE EXTENSION pgcrypto;
CREATE EXTENSION cos_fdw;

CREATE SERVER cos_server FOREIGN DATA WRAPPER cos_fdw OPTIONS(
 host 'xxxxxx.cos.ap-nanjing.myqcloud.com',
 bucket 'xxxxxxxx',
 id 'xxxxxxxx',
 key 'xxxxxxxxxx'
);

CREATE FOREIGN TABLE test_csv (
 word1 text OPTIONS (force_not_null 'true'),
 word2 text OPTIONS (force_not_null 'off') ) SERVER cos_server OPTIONS (
 filepath '/test.csv',
 format 'csv',
 null 'NULL'
);

CREATE FOREIGN TABLE multi_csv (
 word1 text OPTIONS (force_not_null 'true'),
 word2 text OPTIONS (force_not_null 'off') ) SERVER cos_server OPTIONS (
 filepath '/a.csv,/b.csv,/c.csv.2',
 format 'csv',
 null 'NULL'
);

-- Single file
postgres=# EXPLAIN SELECT * FROM test_csv;
 QUERY PLAN 
-----------------------------------------------------------------
--------------
Foreign Scan on test_csv (cost=0.00..1.10 rows=1 width=128)
 Foreign COS Url: https://xxxxxxx.cos.ap-nanjing.myqcloud.com
 Foreign COS File Path: /test_csv.csv
 Foreign each COS File Size(Bytes): 86
 Foreign total COS File Size(Bytes): 86
(5 rows)
-- Multiple files
postgres=# EXPLAIN SELECT * FROM multi_csv;
 QUERY PLAN 
-----------------------------------------------------------------
---------------
Foreign Scan on multi_csv (cost=0.00..1.20 rows=2 width=128)
 Foreign COS Url: https://xxxxxxxxxx.cos.ap-nanjing.myqcloud.com
 Foreign COS File Path: /a.csv,/b.csv,/c.csv.2
 Foreign each COS File Size(Bytes): 15,172,86
 Foreign total COS File Size(Bytes): 273
(5 rows)

postgres=# SELECT * FROM test_csv;
word1 | word2 | word3 | word4 
-------+-------+-------+-------
AAA | aaa | 123 |
XYZ | xyz | | 321
NULL | | |
NULL | | |
ABC | abc | | (5 rows)

postgres=# CREATE TABLE local_test_csv (
postgres(# a text,
postgres(# b text,
postgres(# c text,
postgres(# d text
postgres(# );
CREATE TABLE
postgres=# INSERT INTO local_test_csv SELECT * FROM test_csv;
INSERT 0 5
postgres=# SELECT * FROM local_test_csv;
 a | b | c | d 
------+-----+-----+-----
AAA | aaa | 123 |
XYZ | xyz | | 321
NULL | | |
NULL | | |
ABC | abc | | (5 rows)

postgres=# CREATE TABLE pt (a int, b text) partition by list (a);
CREATE TABLE
postgres=# CREATE FOREIGN TABLE p1 partition of pt for values in (1) SERVER
cos_server
postgres-# OPTIONS (format 'csv', filepath '/list1.csv', delimiter ',');
CREATE FOREIGN TABLE
postgres=# CREATE TABLE p2 partition of pt for values in (2);
CREATE TABLE
-- Partitioned tables can be queried
postgres=# SELECT tableoid::regclass, * FROM pt;
tableoid | a | b 
----------+---+-----
p1 | 1 | foo
p1 | 1 | bar
(2 rows)
postgres=# SELECT tableoid::regclass, * FROM p1;
tableoid | a | b 
----------+---+-----
p1 | 1 | foo
p1 | 1 | bar
(2 rows)
postgres=# SELECT tableoid::regclass, * FROM p2;
tableoid | a | b 
----------+---+---
(0 rows)
-- Currently, data cannot be written to foreign tables
postgres=# INSERT INTO pt VALUES (1, 'xyzzy'); -- ERROR
ERROR: cannot route inserted tuples to a foreign table
-- As local tables are not affected, data can be written to local partitioned tables normally.
postgres=# INSERT INTO pt VALUES (2, 'xyzzy');
INSERT 0 1
postgres=# SELECT tableoid::regclass, * FROM pt;
tableoid | a | b 
----------+---+-------
p1 | 1 | foo
p1 | 1 | bar
p2 | 2 | xyzzy
(3 rows)
postgres=# SELECT tableoid::regclass, * FROM p1;
tableoid | a | b 
----------+---+-----
p1 | 1 | foo
p1 | 1 | bar
(2 rows)
postgres=# SELECT tableoid::regclass, * FROM p2;
tableoid | a | b 
----------+---+-------
p2 | 2 | xyzzy
(1 row)

DROP EXTENSION cos_fdw;