postgres=# select length(lpad('123',0,'*')) from dual;
length
---------
-
-(1 row)
+--------(1 row)
postgres=# select length(lpad('123',0,'*')) from dual; -length --------- -0 +postgres=# select length(lpad('123',0,'*')) from dual;length0 (1 row)- + Specifies the compatibility of variadic results of the concat() and concat_ws() functions.
-If this item is specified and a concat function has a parameter of the variadic type, different result formats in O and Teradata are retained. If this item is not specified and a concat function has a parameter of the variadic type, the result format of O is retained for both O and Teradata. This option has no effect on MY because MY has no variadic type.
-Specifies the compatibility of variadic results of the concat() and concat_ws() functions.
If this item is specified and a concat function has a parameter of the variadic type, different result formats in O and Teradata are retained. If this item is not specified and a concat function has a parameter of the variadic type, the result format of O is retained for both O and Teradata. This option has no effect on MY because MY has no variadic type.
diff --git "a/content/zh/docs/Developerguide/\345\205\266\345\256\203\351\200\211\351\241\271.md" "b/content/zh/docs/Developerguide/\345\205\266\345\256\203\351\200\211\351\241\271.md" index 300fcd3bfa3d69891e84cbfd5c56601f49add6ce..0a7cd9773819cd29b9b6a140554af79365cfc444 100644 --- "a/content/zh/docs/Developerguide/\345\205\266\345\256\203\351\200\211\351\241\271.md" +++ "b/content/zh/docs/Developerguide/\345\205\266\345\256\203\351\200\211\351\241\271.md" @@ -288,31 +288,24 @@ add_months - + Controls the UPDATE operation if a data record in the destination table conflicts with multiple source data records when MERGE INTO ... WHEN MATCHED THEN UPDATE (see MERGE INTO) and INSERT ... ON DUPLICATE KEY UPDATE (see INSERT) are used.
-If this item is specified and the preceding scenario exists, the system performs multiple UPDATE operations on the conflicting row. If this item is not specified and the preceding scenario exists, an error is reported, that is, the MERGE or INSERT operation fails.
-Controls the UPDATE operation if a data record in the destination table conflicts with multiple source data records when MERGE INTO ... WHEN MATCHED THEN UPDATE (see MERGE INTO) and INSERT ... ON DUPLICATE KEY UPDATE (see INSERT) are used.
If this item is specified and the preceding scenario exists, the system performs multiple UPDATE operations on the conflicting row. If this item is not specified and the preceding scenario exists, an error is reported, that is, the MERGE or INSERT operation fails.
postgres=# select length(lpad('123',0,'*')) from dual; length -------- - (1 row)
postgres=# select length(lpad('123',0,'*')) from dual; -length --------- -0 +postgres=# select length(lpad('123',0,'*')) from dual;length0 (1 row)- + 控制函数concat()和concat_ws()对variadic类型结果兼容性的配置项。
-若设置此配置项，当concat函数参数为variadic类型时，保留a db和Teradata兼容模式下不同的结果形式；否则默认a db和Teradata兼容模式下结果相同，且与a db保持一致。由于MY无variadic类型，所以该选项对MY无影响。
-控制函数concat()和concat_ws()对variadic类型结果兼容性的配置项。
若设置此配置项，当concat函数参数为variadic类型时，保留a db和Teradata兼容模式下不同的结果形式；否则默认a db和Teradata兼容模式下结果相同，且与a db保持一致。由于MY无variadic类型，所以该选项对MY无影响。
+ - - 控制在使用MERGE INTO ... WHEN MATCHED THEN UPDATE（参考MERGE INTO） 和INSERT ... ON DUPLICATE KEY UPDATE（参考INSERT）时，当目标表中一条目标数据与多条源数据冲突时UPDATE行为。
-若设置此配置项，当存在上述场景时，该冲突行将会多次执行UPDATE；否则（默认）报错，即MERGE或INSERT操作失败。
-+ + ## table\_skewness\_warning\_threshold **参数说明**：设置用于表倾斜告警的阈值。 控制在使用MERGE INTO ... WHEN MATCHED THEN UPDATE（参考MERGE INTO） 和INSERT ... ON DUPLICATE KEY UPDATE（参考INSERT）时，当目标表中一条目标数据与多条源数据冲突时UPDATE行为。
若设置此配置项，当存在上述场景时，该冲突行将会多次执行UPDATE；否则（默认）报错，即MERGE或INSERT操作失败。