使用COPY ON CONFLICT覆蓋導(dǎo)入數(shù)據(jù)
AnalyticDB PostgreSQL版支持COPY ON CONFLICT覆蓋導(dǎo)入數(shù)據(jù)。目前COPY ON CONFLICT僅支持全表約束檢查及全列覆蓋寫(xiě)入。
在AnalyticDB PostgreSQL版中，您可以通過(guò)COPY快速導(dǎo)入數(shù)據(jù)，但是在COPY導(dǎo)入數(shù)據(jù)的過(guò)程中，如果數(shù)據(jù)與表的約束沖突，COPY任務(wù)會(huì)報(bào)錯(cuò)并終止。AnalyticDB PostgreSQL提供了COPY ON CONFLICT功能，支持在約束沖突時(shí)進(jìn)行覆蓋寫(xiě)入或忽略寫(xiě)入，避免COPY任務(wù)因?yàn)榧s束沖突而失敗。
僅內(nèi)核編譯日期為20210528及以后的AnalyticDB PostgreSQL 6.0版實(shí)例支持COPY ON CONFLICT功能。為了更好地使用該功能，建議您升級(jí)至最新的內(nèi)核版本，升級(jí)內(nèi)核小版本，請(qǐng)參見(jiàn)版本升級(jí)。
使用約束
目標(biāo)表需為堆表，不支持AO表（AO表不支持唯一索引，所以不支持AO表）。
僅V6.3.6.1及以上內(nèi)核版本支持目標(biāo)表為分區(qū)表。如何升級(jí)內(nèi)核版本，請(qǐng)參見(jiàn)版本升級(jí)。
目標(biāo)表不支持Updatable View（可更新視圖）。
COPY ON CONFLICT僅支持COPY FROM，不支持COPY TO。
不支持指定約束索引列，COPY ON CONFLICT默認(rèn)判斷所有約束列。若指定約束索引列，則COPY執(zhí)行失敗，報(bào)錯(cuò)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默認(rèn)更新所有列。若指定更新列，則COPY執(zhí)行失敗，報(bào)錯(cuò)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
語(yǔ)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兩個(gè)子句：
DO ON CONFLICT DO UPDATE表示表約束沖突時(shí)全列更新。
DO ON CONFLICT DO NOTHING表示表約束沖突時(shí)忽略輸入內(nèi)容。
示例
創(chuàng)建一個(gè)表NATION，表中包含4列，其中N_NATIONKEY為主鍵列，具有主鍵約束，建表語(yǔ)句如下：
CREATE TABLE NATION ( N_NATIONKEY INTEGER, N_NAME CHAR(25), N_REGIONKEY INTEGER, N_COMMENT VARCHAR(152), PRIMARY KEY (N_NATIONKEY) );通過(guò)COPY導(dǎo)入部分?jǐn)?shù)據(jù)，COPY語(yǔ)句如下：
COPY NATION FROM stdin;出現(xiàn)>>標(biāo)志后逐條輸入如下內(nèi)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' \.說(shuō)明復(fù)制以上數(shù)據(jù)時(shí)，請(qǐng)將兩列值之間的空格替換為Tab。
查詢NATION表，查看已經(jīng)導(dǎo)入的數(shù)據(jù)，查詢語(yǔ)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語(yǔ)句導(dǎo)入一行主鍵沖突的數(shù)據(jù)，COPY語(yǔ)句如下：
COPY NATION FROM stdin;出現(xiàn)>>標(biāo)志后逐條輸入如下內(nèi)容：
0 'GERMANY' 3 'l platelets. regular accounts x-ray: unusual, regular acco' \.說(shuō)明復(fù)制以上數(shù)據(jù)時(shí)，請(qǐng)將兩列值之間的空格替換為Tab。
此時(shí)執(zhí)行會(huì)產(chǎn)生報(bào)錯(cuò)，報(bào)錯(cuò)內(nèi)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語(yǔ)句，在主鍵沖突的情況下更新數(shù)據(jù)，COPY ON CONFLICT語(yǔ)句如下：
COPY NATION FROM stdin DO ON CONFLICT DO UPDATE;出現(xiàn)>>標(biāo)志后逐條輸入如下內(nèi)容：
0 'GERMANY' 3 'l platelets. regular accounts x-ray: unusual, regular acco' \.說(shuō)明復(fù)制以上數(shù)據(jù)時(shí)，請(qǐng)將兩列值之間的空格替換為Tab。
此時(shí)COPY語(yǔ)句不會(huì)產(chǎn)生報(bào)錯(cuò)信息，查詢NATION表可以看到主鍵為0的行數(shù)據(jù)已更新，查詢語(yǔ)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，在主鍵沖突的情況下，忽略輸入：
COPY NATION FROM stdin DO ON CONFLICT DO NOTHING;出現(xiàn)>>標(biāo)志后逐條輸入如下內(nèi)容：
1 'GERMANY' 3 'l platelets. regular accounts x-ray: unusual, regular acco' \.說(shuō)明復(fù)制以上數(shù)據(jù)時(shí)，請(qǐng)將兩列值之間的空格替換為Tab。
此時(shí)COPY語(yǔ)句不會(huì)產(chǎn)生報(bào)錯(cuò)信息，查詢NATION表可以看到主鍵為1的行數(shù)據(jù)沒(méi)有更新，查詢語(yǔ)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)