Deleting duplicate rows from a table is a little bit tricky. Finding and deleting duplicate rows is pretty easy if the table has a limited number of records. However, if the table has enormous data, then finding and deleting the duplicates can be challenging. PostgreSQL provides multiple ways ...
Except one, Delete all duplicate records: 1 2 3 4 5 6 7 DELETE FROM tbl_RemoveDuplicate WHERE ID IN (SELECT ID FROM (SELECT id, ROW_NUMBER() OVER (partition BY Name ORDER BY ID) AS RowNumber FROM tbl_RemoveDuplicate) AS T WHERE T.RowNumber > 1); Check the result: 1 2 3 ...
Merge Join (cost=1.47..47922.57 rows=99040 width=93) Merge Cond: (a.id = b.id) -> Index Scan using idx_testtab01_id on testtab01 a (cost=0.43..413538.43 rows=10000000 width=89) -> Index Only Scan using idx_testtab02_id on testtab02 b (cost=0.42..4047.63 rows=99040 width=4)...
mydb=> SELECT ctid,* FROM test_sample TABLESAMPLE SYSTEM(0.01); ctid | id | message | create_time ---+---+---+--- (5640,1) | 603481 | 385484b3452b245e46388d71ce4ea928 | 2017-08-08 21:17:23.32394 (5640,2) | 603482 | e09c526118f1d4b3c391d59ae915c4e8 | 2017-08-08 2...
mydb=>CREATETABLEtbl_batch3(id int4,info text);CREATETABLEmydb=>INSERTINTOtbl_batch3(id,info)VALUES(1,'a'),(2,'b'),(3,'c');INSERT0 3 1. 2. 3. 4. 5. 数据如下: 复制 mydb=>SELECT*FROMtbl_batch3;id | info---+---1 | a2 | b3 | c(3rows) 1. 2...
mydb=> DELETE FROM test_r1 WHERE id=2 RETURNING *; id | flag ---+--- 2 | b (1 row) DELETE 1 UPSERT PostgreSQL的UPSERT特性是指 INSERT ... ON CONFLICT UPDATE,用来解决在数据插入过程中数据冲突的情况,比如违反用户自定义约束,日志数据应用场景通常在事务中批量插入日志数据,如果其中有一条数据...
id | name ---+--- 1 | abc 2 | bcd (2 rows) __xtest__N2=# select * from t; id | name ---+--- 1 | abc 2 | bcd (2 rows) (六)创建一个partition模式的表 Stado -> create table t2 (area_id int,area_name varchar(20),descs text) partitioning key area_id on all; OK...
if any *//* If query can insert/delete tuples, the command ID to mark them with */CommandId es_output_cid;/* Info about target table(s) for insert/update/delete queries: */ResultRelInfo *es_result_relations;/* array of ResultRelInfos */intes_num_result_relations;/* length of array...
(2 rows) postgres=# delete from test where id=1; DELETE 1 postgres=# select * from test; id | info | crt_time ---+---+--- (0 rows) postgres=# select * from table_change_rec; id | relid | table_schema | table_name | when_tg | level | op | old_rec | new_rec | crt...
Introduced support to correlated subquery transform and cache for enhancement of query performance by transforming scalar correlated subquery into join query, or caching the subquery result set and reduce duplicate subquery re-executions when transformation is not possible. For more information, see Improvi...