AnalyticDB PostgreSQL版支持COPY ON CONFLICT覆盖导入数据。目前COPY ON CONFLICT仅支持全表约束检查及全列覆盖写入。
在AnalyticDB PostgreSQL版中，您可以通过COPY快速导入数据，但是在COPY导入数据的过程中，如果数据与表的约束冲突，COPY任务会报错并终止。AnalyticDB PostgreSQL提供了COPY ON CONFLICT功能，支持在约束冲突时进行覆盖写入或忽略写入，避免COPY任务因为约束冲突而失败。
仅内核编译日期为20210528及以后的AnalyticDB PostgreSQL 6.0版实例支持COPY ON CONFLICT功能。为了更好地使用该功能，建议您升级至最新的内核版本，升级内核小版本，请参见版本升级。
使用约束
目标表需为堆表，不支持AO表（AO表不支持唯一索引，所以不支持AO表）。
仅V6.3.6.1及以上内核版本支持目标表为分区表。如何升级内核版本，请参见版本升级。
目标表不支持Updatable View（可更新视图）。
COPY ON CONFLICT仅支持COPY FROM，不支持COPY TO。
不支持指定约束索引列，COPY ON CONFLICT默认判断所有约束列。若指定约束索引列，则COPY执行失败，报错信息如下：
COPY NATION FROM stdin DO ON CONFLICT(n_nationkey) DO UPDATE; ERROR: COPY ON CONFLICT does NOT support CONFLICT index params不支持指定更新列，COPY ON CONFLICT默认更新所有列。若指定更新列，则COPY执行失败，报错信息如下：
COPY NATION FROM stdin DO ON CONFLICT DO UPDATE SET n_nationkey = excluded.n_nationkey; ERROR: COPY ON CONFLICT does NOT support UPDATE SET targets
语法
COPY table [(column [, ...])] FROM {'file' | STDIN}
[ [WITH]
[BINARY]
[OIDS]
[HEADER]
[DELIMITER [ AS ] 'delimiter']
[NULL [ AS ] 'null string']
[ESCAPE [ AS ] 'escape' | 'OFF']
[NEWLINE [ AS ] 'LF' | 'CR' | 'CRLF']
[CSV [QUOTE [ AS ] 'quote']
[FORCE NOT NULL column [, ...]]
[FILL MISSING FIELDS]
[[LOG ERRORS]
SEGMENT REJECT LIMIT count [ROWS | PERCENT] ]
[DO ON CONFLICT DO UPDATE | NOTHING]COPY ON CONFLICT提供了DO ON CONFLICT DO UPDATE和DO ON CONFLICT DO NOTHING两个子句：
DO ON CONFLICT DO UPDATE表示表约束冲突时全列更新。
DO ON CONFLICT DO NOTHING表示表约束冲突时忽略输入内容。
示例
创建一个表NATION，表中包含4列，其中N_NATIONKEY为主键列，具有主键约束，建表语句如下：
CREATE TABLE NATION ( N_NATIONKEY INTEGER, N_NAME CHAR(25), N_REGIONKEY INTEGER, N_COMMENT VARCHAR(152), PRIMARY KEY (N_NATIONKEY) );通过COPY导入部分数据，COPY语句如下：
COPY NATION FROM stdin;出现>>标志后逐条输入如下内容：
0 'ALGERIA' 0 'haggle. carefully final deposits detect slyly agai' 1 'ARGENTINA' 1 'al foxes promise slyly according to the regular accounts. bold requests alon' 2 'BRAZIL' 1 'y alongside of the pending deposits. carefully special packages are about the ironic forges. slyly speci' 3 'CANADA' 1 'eas hang ironic, silent packages. slyly regular packages are furiously over the tithes. fluffily bold' \.说明复制以上数据时，请将两列值之间的空格替换为Tab。
查询NATION表，查看已经导入的数据，查询语句如下：
SELECT * from NATION;返回信息如下：
n_nationkey | n_name | n_regionkey | n_comment -------------+---------------------------+-------------+------------------------------------------------------------------------------------------------------------ 2 | 'BRAZIL' | 1 | 'y alongside of the pending deposits. carefully special packages are about the ironic forges. slyly speci' 3 | 'CANADA' | 1 | 'eas hang ironic, silent packages. slyly regular packages are furiously over the tithes. fluffily bold' 0 | 'ALGERIA' | 0 | ' haggle. carefully final deposits detect slyly agai' 1 | 'ARGENTINA' | 1 | 'al foxes promise slyly according to the regular accounts. bold requests alon' (4 rows)使用COPY语句导入一行主键冲突的数据，COPY语句如下：
COPY NATION FROM stdin;出现>>标志后逐条输入如下内容：
0 'GERMANY' 3 'l platelets. regular accounts x-ray: unusual, regular acco' \.说明复制以上数据时，请将两列值之间的空格替换为Tab。
此时执行会产生报错，报错内容如下：
ERROR: duplicate key value violates unique constraint "nation_pkey" DETAIL: Key (n_nationkey)=(0) already exists. CONTEXT: COPY nation, line 1使用COPY ON CONFLICT语句，在主键冲突的情况下更新数据，COPY ON CONFLICT语句如下：
COPY NATION FROM stdin DO ON CONFLICT DO UPDATE;出现>>标志后逐条输入如下内容：
0 'GERMANY' 3 'l platelets. regular accounts x-ray: unusual, regular acco' \.说明复制以上数据时，请将两列值之间的空格替换为Tab。
此时COPY语句不会产生报错信息，查询NATION表可以看到主键为0的行数据已更新，查询语句如下：
SELECT * FROM NATION;返回信息如下：
n_nationkey | n_name | n_regionkey | n_comment -------------+---------------------------+-------------+------------------------------------------------------------------------------------------------------------ 2 | 'BRAZIL' | 1 | 'y alongside of the pending deposits. carefully special packages are about the ironic forges. slyly speci' 3 | 'CANADA' | 1 | 'eas hang ironic, silent packages. slyly regular packages are furiously over the tithes. fluffily bold' 1 | 'ARGENTINA' | 1 | 'al foxes promise slyly according to the regular accounts. bold requests alon' 0 | 'GERMANY' | 3 | 'l platelets. regular accounts x-ray: unusual, regular acco' (4 rows)使用COPY ON CONFLICT功能，在主键冲突的情况下，忽略输入：
COPY NATION FROM stdin DO ON CONFLICT DO NOTHING;出现>>标志后逐条输入如下内容：
1 'GERMANY' 3 'l platelets. regular accounts x-ray: unusual, regular acco' \.说明复制以上数据时，请将两列值之间的空格替换为Tab。
此时COPY语句不会产生报错信息，查询NATION表可以看到主键为1的行数据没有更新，查询语句如下：
SELECT * FROM NATION;返回信息如下：
n_nationkey | n_name | n_regionkey | n_comment -------------+---------------------------+-------------+------------------------------------------------------------------------------------------------------------ 2 | 'BRAZIL' | 1 | 'y alongside of the pending deposits. carefully special packages are about the ironic forges. slyly speci' 3 | 'CANADA' | 1 | 'eas hang ironic, silent packages. slyly regular packages are furiously over the tithes. fluffily bold' 1 | 'ARGENTINA' | 1 | 'al foxes promise slyly according to the regular accounts. bold requests alon' 0 | 'GERMANY' | 3 | 'l platelets. regular accounts x-ray: unusual, regular acco' (4 rows)