Java/Spring JDBC:批量插入 2 个表:从第 1 批插入获取第 2 个表所需的 FK ID
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【中文标题】Java/Spring JDBC:批量插入 2 个表:从第 1 批插入获取第 2 个表所需的 FK ID【英文标题】:Java/Spring JDBC: Batch Insert into 2 Tables: Obtain FK ID from 1st Batch Insert Required for 2nd Table 【发布时间】:2020-06-06 21:56:50 【问题描述】:我正在使用jdbcTemplate
批量插入到 2 个表中。第一张桌子很简单,有一个ID
。第二个表有一个 FK 参考 USER_ID
,我需要在插入之前从表 1 中获取它。
假设我有这个:
主要 Java 代码(这里我分成多个批次
for(int i = 0; i < totalEntries.size(); i++)
// Add to Batch-Insert List; if list size ready for batch-insert, or if at the end, batch-persist & clear list
batchInsert.add(user);
if (batchInsert.size() == 1000 || i == totalEntries.size() - 1)
// 1. Batch is ready, insert into Table 1
nativeBatchInsertUsers(jdbcTemplate, batchInsert);
// 2. Batch is ready, insert into Table 2
nativeBatchInsertStudyParticipants(jdbcTemplate, batchInsert);
// Reset list
batchInsert.clear();
批量插入表 1 的方法(注意,我在这里为 USERS_T 获取 Seq Val)
private void nativeBatchInsertUsers(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsert)
String sqlInsert_USERS_T = "INSERT INTO PUBLIC.USERS_T (id, password, user_name) " +
"VALUES (nextval('users_t_id_seq'), ?, ? " +
")";
// Insert into USERS_T using overridden JdbcTemplate's Native-SQL batchUpdate() on the string "sqlInsert_USERS_T"
jdbcTemplate.batchUpdate(sqlInsert_USERS_T, new BatchPreparedStatementSetter()
@Override
public int getBatchSize()
return batchInsert.size();
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException
ps.setString(1, null);
ps.setString(2, batchInsert.get(i).getUsername());
// etc.
);
批量插入表2的方法
private void nativeBatchInsertStudyParticipants(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsertUsers)
String sqlInsert_STUDY_PARTICIPANTS_T =
"INSERT INTO PUBLIC.STUDY_PARTICIPANTS_T (id, study_id, subject_id, user_id) "
"VALUES (nextval('study_participants_t_id_seq'), ?, ?, ?
")";
// Insert into STUDY_PARTICIPANTS_T using overridden JdbcTemplate's Native-SQL batchUpdate() on the string "sqlInsert_USERS_T"
jdbcTemplate.batchUpdate(sqlInsert_STUDY_PARTICIPANTS_T, new BatchPreparedStatementSetter()
@Override
public int getBatchSize()
return batchInsert.size();
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException
// PROBLEM: For Param #4, USER_ID, need to get the USERS_T.ID from Batch-Insert #1
);
当我来到第二批插入时,其中一列是返回到 USERS_T.ID
的 FK,称为 STUDY_PARTICIPANTS_T.USER_ID
。我是否可以通过保持jdbcTemplate.batchUpdate()
逻辑来获得它?
【问题讨论】:
【参考方案1】:这就是答案。
1) 如果您使用jdbcTemplate
(Spring JDBC),一种解决方案是提前保留您自己的 ID 范围。然后自己为每一行提供手动计算的 ID。例如
@Transactional(readOnly = false, rollbackFor = Exception.class)
public void doMultiTableInsert(List<String> entries) throws Exception
// 1. Obtain current Sequence values
Integer currTable1SeqVal = table1DAO.getCurrentTable1SeqVal();
Integer currTable2SeqVal = table2DAO.getCurrentTable2SeqVal();
// 2. Immediately update the Sequences to the calculated final value (this reserves the ID range immediately)
table1DAO.setTable1SeqVal(currTable1SeqVal + entries.size());
table2DAO.setTable2SeqVal(currTable2SeqVal + entries.size());
for(int i = 0; i < entries.size(); i++)
// Prepare Domain object...
UsersT user = new User();
user.setID(currTable1SeqVal + 1 + i); // Set ID manually
user.setCreatedDate(new Date());
// etc.
StudyParticipantsT sp = new StudyParticipantsT();
sp.setID(currTable2SeqVal + 1 + i); // Set ID manually
// etc.
user.setStudyParticipant(sp);
// Add to Batch-Insert List
batchInsertUsers.add(user);
// If list size ready for Batch-Insert (in this ex. 1000), or if at the end of all subjectIds, perform Batch Insert (both tables) and clear list
if (batchInsertUsers.size() == 1000 || i == subjectIds.size() - 1)
// Part 1: Insert batch into USERS_T
nativeBatchInsertUsers(jdbcTemplate, batchInsertUsers);
// Part 2: Insert batch into STUDY_PARTICIPANTS_T
nativeBatchInsertStudyParticipants(jdbcTemplate, batchInsertUsers);
// Reset list
batchInsertUsers.clear();
然后是上面引用的 Batch-Insert 子方法:
1)
private void nativeBatchInsertUsers(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsertUsers)
String sqlInsert = "INSERT INTO PUBLIC.USERS_T (id, password, ... )"; // etc.
jdbcTemplate.batchUpdate(sqlInsert, new BatchPreparedStatementSetter()
@Override
public int getBatchSize()
return batchInsertUsers.size();
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException
ps.setInt(1, batchInsertUsers.get(i).getId()); // ID (provided by ourselves)
ps.setDate(2, batchInsertUsers.get(i).getCreatedDate());
//etc.
);
2)
private void nativeBatchInsertStudyParticipants(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsertUsers)
String sqlInsert = "INSERT INTO PUBLIC.STUDY_PARTICIPANTS_T (id, ... )"; // etc.
jdbcTemplate.batchUpdate(sqlInsert, new BatchPreparedStatementSetter()
@Override
public int getBatchSize()
return batchInsertUsers.size();
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException
ps.setInt(1, batchInsertUsers.get(i).getStudyParticipants().getId()); // ID (provided by ourselves)
//etc.
);
有一些方法可以获取/设置序列值,例如在 Postgres 中是
SELECT last_value FROM users_t_id_seq; -- GET SEQ VAL
SELECT setval('users_t_id_seq', 621938); -- SET SEQ VAL
还要注意,所有内容都在@Transactional
之下。如果方法中有任何异常,所有数据都会回滚(对于 all 异常,rollbackFor = Exception.class
)。唯一不会回滚的是手动序列更新。不过没关系,序列可以有间隙。
2) 如果您愿意降级到PreparedStatement
级别,另一种解决方案是Statement.RETURN_GENERATED_KEYS
:
PreparedStatement ps = con.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)
在您执行ps
后,ResultSet
将按照创建顺序包含您的 ID。您可以遍历 ResultSet 并将 ID 存储在单独的列表中。
while (rs.next())
generatedIDs.add(rs.getInt(1));
请记住,在这种情况下,您负责自己的事务管理。你需要conn.setAutoCommit(false);
让批次堆积起来,没有真正的持久性,然后conn.commit();
/ conn.rollback();
。
【讨论】:
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