Copy命令在PG 12有所增强,在COPY FROM时可添加WHERE条件过滤. **PG 11** Copy命令 ``` testdb=# \help copy Command: COPY Description: copy data between a file and a table Syntax: COPY table_name [ ( column_name [, ...] ) ] FROM { 'filename' | PROGRAM 'command' | STDIN } [ [ WITH ] ( option [, ...] ) ] COPY { table_name [ ( column_name [, ...] ) ] | ( query ) } TO { 'filename' | PROGRAM 'command' | STDOUT } [ [ WITH ] ( option [, ...] ) ] where option can be one of: FORMAT format_name OIDS [ boolean ] FREEZE [ boolean ] DELIMITER 'delimiter_character' NULL 'null_string' HEADER [ boolean ] QUOTE 'quote_character' ESCAPE 'escape_character' FORCE_QUOTE { ( column_name [, ...] ) | * } FORCE_NOT_NULL ( column_name [, ...] ) FORCE_NULL ( column_name [, ...] ) ENCODING 'encoding_name' ``` 简单使用 ``` testdb=# drop table if exists t_copy; DROP TABLE testdb=# CREATE TABLE t_copy(id int,c1 varchar(20)); CREATE TABLE testdb=# insert into t_copy SELECT x,'c1-'||x FROM generate_series(1, 1000) AS x; INSERT 0 1000 testdb=# testdb=# COPY t_copy TO '/tmp/data/t_copy.txt' with DELIMITER '|'; COPY 1000 testdb=# drop table if exists t_import; DROP TABLE testdb=# CREATE TABLE t_import(id int,c1 varchar(20)); CREATE TABLE testdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|'; COPY 1000 testdb=# select * from t_import limit 10; id | c1 ----+------- 1 | c1-1 2 | c1-2 3 | c1-3 4 | c1-4 5 | c1-5 6 | c1-6 7 | c1-7 8 | c1-8 9 | c1-9 10 | c1-10 (10 rows) ``` 不支持WHERE条件过滤 ``` testdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|' where id < 5; ERROR: syntax error at or near "where" LINE 1: ...t FROM '/tmp/data/t_copy.txt' with DELIMITER '|' where id <... ``` **PG 12** COPY命令语法 ``` [local]:5432 pg12@testdb=# \help copy Command: COPY Description: copy data between a file and a table Syntax: COPY table_name [ ( column_name [, ...] ) ] FROM { 'filename' | PROGRAM 'command' | STDIN } [ [ WITH ] ( option [, ...] ) ] [ WHERE condition ] COPY { table_name [ ( column_name [, ...] ) ] | ( query ) } TO { 'filename' | PROGRAM 'command' | STDOUT } [ [ WITH ] ( option [, ...] ) ] where option can be one of: FORMAT format_name FREEZE [ boolean ] DELIMITER 'delimiter_character' NULL 'null_string' HEADER [ boolean ] QUOTE 'quote_character' ESCAPE 'escape_character' FORCE_QUOTE { ( column_name [, ...] ) | * } FORCE_NOT_NULL ( column_name [, ...] ) FORCE_NULL ( column_name [, ...] ) ENCODING 'encoding_name' URL: https://www.postgresql.org/docs/12/sql-copy.html ``` 支持WHERE条件过滤 ``` [local]:5432 pg12@testdb=# drop table if exists t_copy; DROP TABLE Time: 50.327 ms [local]:5432 pg12@testdb=# CREATE TABLE t_copy(id int,c1 varchar(20)); CREATE TABLE Time: 5.038 ms [local]:5432 pg12@testdb=# insert into t_copy SELECT x,'c1-'||x FROM generate_series(1, 1000) AS x; INSERT 0 1000 Time: 16.422 ms [local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# COPY t_copy TO '/tmp/data/t_copy.txt' with DELIMITER '|'; COPY 1000 Time: 4.795 ms [local]:5432 pg12@testdb=# drop table if exists t_import; DROP TABLE Time: 4.798 ms [local]:5432 pg12@testdb=# CREATE TABLE t_import(id int,c1 varchar(20)); CREATE TABLE Time: 2.462 ms [local]:5432 pg12@testdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|' WHERE id < 5; COPY 4 Time: 4.842 ms [local]:5432 pg12@testdb=# select * from t_import; id | c1 ----+------ 1 | c1-1 2 | c1-2 3 | c1-3 4 | c1-4 (4 rows) Time: 6.103 ms ``` **参考资料** [Tech preview: Improving COPY and bulkloading in PostgreSQL 12](https://www.cybertec-postgresql.com/en/tech-preview-improving-copy-and-bulkloading-in-postgresql-12/)