我正在尝试使用 Node.js 和“oracledb”节点执行以下操作：
list。.map()，list并在此功能内部咨询数据库 B 以通过公共密钥获取客户的信息，对于list.问题是：数据库 B 的请求是一起完成的，所以如果有 1000 个账单要映射，它只返回 100 个并将其余的视为错误。大概和同时请求的数量有关。
因此，鉴于详细信息，我想知道是否有办法划分请求数量（例如当时的 100 个）或任何其他解决方案。
ps.：我提前为我的错误道歉。我也为没有在代码上演示而道歉。
这是一个示例，说明如何通过利用executeManyv2.2.0（最近发布）中的新功能和全局临时表来最大程度地减少往返行程。
给定这些对象：
-- Imagine this is the table you want to select from based on the common keys
create table t (
common_key number,
info varchar2(50)
);
-- Add 10,000 rows with keys 1-10,000 and random data for info
insert into t (common_key, info)
select rownum,
dbms_random.string('p', 50)
from dual
connect by rownum <= 10000;
commit;
-- Create a temp table
create global temporary table temp_t (
common_key number not null
)
on commit delete rows;
以下应该有效：
const oracledb = require('oracledb');
const config = require('./dbConfig.js');
const startKey = 1000;
const length = 2000;
// Uses a promise to simulate async work.
function getListFromDatabaseA() {
return new Promise((resolve) => {
const list = [];
const count = length - startKey;
for (let x = 0; x < count; x += 1) {
list.push(startKey + x);
}
resolve(list);
});
}
// The list returned from A likely isn't in the right format for executeMany.
function reformatAsBinds(list) {
const binds = [];
for (let x = 0; x < list.length; x += 1) {
binds.push({
key: list[x]
});
}
return binds;
}
async function runTest() {
let conn;
try {
const listFromA = await getListFromDatabaseA();
const binds = reformatAsBinds(listFromA);
conn = await oracledb.getConnection(config);
// Send the keys to the temp table with executeMany for a single round trip.
// The data in the temp table will only be visible to this session and will
// be deleted automatically at the end of the transaction.
await conn.executeMany('insert into temp_t (common_key) values (:key)', binds);
// Now get your common_key and info based on the common keys in the temp table.
let result = await conn.execute(
`select common_key, info
from t
where common_key in (
select common_key
from temp_t
)
order by common_key`
);
console.log('Got ' + result.rows.length + ' rows');
console.log('Showing the first 10 rows');
for (let x = 0; x < 10; x += 1) {
console.log(result.rows[x]);
}
} catch (err) {
console.error(err);
} finally {
if (conn) {
try {
await conn.close();
} catch (err) {
console.error(err);
}
}
}
}
runTest();
在我发布了上面的解决方案之后，我认为我应该提供一个替代方案，让密钥从 Node.js 到“内存中”的 DB。您必须运行测试并查看解释计划，看看哪个是您的最佳选择（取决于许多因素）。
给定这些对象：
-- This is the same as before
create table t (
common_key number,
info varchar2(50)
);
-- Add 10,000 rows with keys 1-10,000 and random data for info
insert into t (common_key, info)
select rownum,
dbms_random.string('p', 50)
from dual
connect by rownum <= 10000;
-- But here, we use a nested table instead of a temp table
create or replace type number_ntt as table of number;
这应该有效：
const oracledb = require('oracledb');
const config = require('./dbConfig.js');
const startKey = 1000;
const length = 2000;
// Uses a promise to simulate async work.
function getListFromDatabaseA() {
return new Promise((resolve) => {
const list = [];
const count = length - startKey;
for (let x = 0; x < count; x += 1) {
list.push(startKey + x);
}
resolve(list);
});
}
async function runTest() {
let conn;
try {
const listFromA = await getListFromDatabaseA();
const binds = {
keys: {
type: oracledb.NUMBER,
dir: oracledb.BIND_IN,
val: listFromA
},
rs: {
type: oracledb.CURSOR,
dir: oracledb.BIND_OUT
}
};
conn = await oracledb.getConnection(config);
// Now get your common_key and info based on what's in the temp table.
let result = await conn.execute(
`declare
type number_aat is table of number index by pls_integer;
l_keys number_aat;
l_key_tbl number_ntt := number_ntt();
begin
-- Unfortunately, we have to bind in with this data type, but
-- it can't be used as a table...
l_keys := :keys;
-- So we'll transfer the data to another array type that can. This
-- variable's type was created at the schema level so that it could
-- be seen by the SQL engine.
for x in 1 .. l_keys.count
loop
l_key_tbl.extend();
l_key_tbl(l_key_tbl.count) := l_keys(x);
end loop;
open :rs for
select common_key, info
from t
where common_key in (
select column_value
from table(l_key_tbl)
)
order by common_key;
end;`,
binds
);
const resultSet = result.outBinds.rs;
console.log('Showing the first 10 rows');
for (x = 0; x < 10; x += 1) {
let row = await resultSet.getRow();
console.log(row);
}
} catch (err) {
console.error(err);
} finally {
if (conn) {
try {
await conn.close();
} catch (err) {
console.error(err);
}
}
}
}
runTest();
绑定的格式不同（这里稍微简单一些）。另外，因为我正在执行 PL/SQL，所以我需要一个外绑定游标/结果集类型。
请参阅这篇关于嵌套表基数的帖子： http ://www.oracle-developer.net/display.php?id=427
如果您同时尝试这两种方法，请留下一些反馈，说明哪种效果更好。