如何将数据插入PL/SQL表类型而不是PL/SQL表中? [英] How to insert data into a PL/SQL table type rather than PL/SQL table?
问题描述
我有一个表TDATAMAP,它具有大约1000万条记录,我想将所有记录提取到PL/SQL表类型变量中,并使其与某些条件匹配,最后将所有必需的记录插入到临时表中.请告诉我是否有可能使用PL/SQL表类型变量和BULK INSERT/COLLECT做到这一点.我还担心代码的性能.
I have a table TDATAMAP which has around 10 million records, I want to fetch all the records into a PL/SQL table type variable, match it with some criteria and finally insert all the required records in a staging table. Please tell me if its possible to do it using PL/SQL table typle variable and BULK INSERT/COLLECT . I am also concerned about the performance of the code.
推荐答案
您可以(但可能不应该)一次将1000万条记录加载到内存中-只要有足够的内存来容纳那么多内存即可.通常,BULK COLLECT与LIMIT子句一起使用,一次可处理有限数量的行,例如1000.
You can, but you probably should not, load 10 million records into memory at once - as long as there is sufficient memory to hold that much. Normally BULK COLLECT is used with the LIMIT clause to process a finite number of rows at a time e.g. 1000.
从文档:
BULK COLLECT子句可让您从结果中提取整列 设置,或一次性设置整个结果.下面的例子, 从游标中检索列到集合中:
The BULK COLLECT clause lets you fetch entire columns from the result set, or the entire result set at once. The following example, retrieves columns from a cursor into a collection:
DECLARE
TYPE NameList IS TABLE OF emp.ename%TYPE;
names NameList;
CURSOR c1 IS SELECT ename FROM emp WHERE job = 'CLERK';
BEGIN
OPEN c1;
FETCH c1 BULK COLLECT INTO names;
...
CLOSE c1;
END;
下面的示例使用LIMIT子句.每次迭代 在循环中,FETCH语句按索引方式获取100行(或更少) 表acct_ids.先前的值将被覆盖.
The following example uses the LIMIT clause. With each iteration of the loop, the FETCH statement fetches 100 rows (or less) into index-by table acct_ids. The previous values are overwritten.
DECLARE
TYPE NumList IS TABLE OF NUMBER INDEX BY BINARY_INTEGER;
CURSOR c1 IS SELECT acct_id FROM accounts;
acct_ids NumList;
rows NATURAL := 100; -- set limit
BEGIN
OPEN c1;
LOOP
/* The following statement fetches 100 rows (or less). */
FETCH c1 BULK COLLECT INTO acct_ids LIMIT rows;
EXIT WHEN c1%NOTFOUND;
...
END LOOP;
CLOSE c1;
END;
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