兼容SAMPLE抽样采集语法
atlasdb=# CREATE TABLE test_sample (id int, name text) WITH (fillfactor=10);
CREATE TABLE
atlasdb=#
atlasdb=# INSERT INTO test_sample
atlasdb-# SELECT i, repeat(i::text, 200) FROM generate_series(0, 9) s(i);
INSERT 0 10
atlasdb=# SELECT t.id FROM test_sample AS t SAMPLE BLOCK (50) SEED (0);
id
----
0
1
2
3
4
5
6
7
8
(9 rows)
atlasdb=# SELECT id FROM test_sample SAMPLE BLOCK (100.0/11) SEED (0);
id
----
(0 rows)
atlasdb=# SELECT id FROM test_sample SAMPLE BLOCK (50) SEED (0);
id
----
3
4
5
9
(4 rows)
atlasdb=# SELECT id FROM test_sample SAMPLE (50) SEED (0);
id
----
0
1
2
4
7
9
(6 rows)
atlasdb=# SELECT id FROM test_sample SAMPLE (5.5) SEED (0);
id
----
(0 rows)
