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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 copyCommand: COPYDescription: copy data between a file and a tableSyntax: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 TABLEtestdb=# CREATE TABLE t_copy(id int,c1 varchar(20));CREATE TABLEtestdb=# insert into t_copy SELECT x,'c1-'||x FROM generate_series(1, 1000) AS x;INSERT 0 1000testdb=# testdb=# COPY t_copy TO '/tmp/data/t_copy.txt' with DELIMITER '|';COPY 1000testdb=# drop table if exists t_import;DROP TABLEtestdb=# CREATE TABLE t_import(id int,c1 varchar(20));CREATE TABLEtestdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|';COPY 1000testdb=# 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 copyCommand: COPYDescription: copy data between a file and a tableSyntax: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 TABLETime: 50.327 ms[local]:5432 pg12@testdb=# CREATE TABLE t_copy(id int,c1 varchar(20));CREATE TABLETime: 5.038 ms[local]:5432 pg12@testdb=# insert into t_copy SELECT x,'c1-'||x FROM generate_series(1, 1000) AS x;INSERT 0 1000Time: 16.422 ms[local]:5432 pg12@testdb=# [local]:5432 pg12@testdb=# COPY t_copy TO '/tmp/data/t_copy.txt' with DELIMITER '|';COPY 1000Time: 4.795 ms[local]:5432 pg12@testdb=# drop table if exists t_import;DROP TABLETime: 4.798 ms[local]:5432 pg12@testdb=# CREATE TABLE t_import(id int,c1 varchar(20));CREATE TABLETime: 2.462 ms[local]:5432 pg12@testdb=# COPY t_import FROM '/tmp/data/t_copy.txt' with DELIMITER '|' WHERE id < 5;COPY 4Time: 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
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