问题描述
什么是在cassandra列族中插入多行的最有效的方法。这是可能在一个单一的调用。
What is the most efficient way of inserting multiple rows in cassandra column family. Is it possible to do this in a single call.
现在我的方法是添加插入多个列，然后执行。在一个单独的调用，我坚持一行。我正在寻找策略，以便我可以做一个批插入。
Right now my approach is to addinsert multiple column and then execute. There in a single call I am persisting one row. I am looking for strategy so that I can do a batch insert.
推荐答案
CQL配备了一个BEGIN BATCH ... APPLY BATCH语句，使得可以将多个插入组合在一起，使得开发者可以构建这样的批量请求的字符串并执行它。
[
CQL comes with a BEGIN BATCH...APPLY BATCH statement that makes it possible to group together several inserts, so that a developer can build a string of such a batch request and execute it.[http://www.datastax.com/dev/blog/client-side-improvements-in-cassandra-2-0]
以下适用于我：
PreparedStatement ps = session.prepare(
"BEGIN BATCH" +
"INSERT INTO messages (user_id, msg_id, title, body) VALUES (?, ?, ?, ?);" +
"INSERT INTO messages (user_id, msg_id, title, body) VALUES (?, ?, ?, ?);" +
"INSERT INTO messages (user_id, msg_id, title, body) VALUES (?, ?, ?, ?);" +
"APPLY BATCH" );
session.execute(ps.bind(uid, mid1, title1, body1, uid, mid2, title2, body2, uid, mid3, title3, body3));
如果您事先不知道要执行的语句，可以使用以下语法（Scala）：
If you don't know in advance what statements you want to execute, you can use the following syntax (Scala):
var statement: PreparedStatement = session.prepare("INSERT INTO people (name,age) VALUES (?,?)")
var boundStatement = new BoundStatement(statement)
val batchStmt = new BatchStatement()
batchStmt.add(boundStatement.bind("User A", "10"))
batchStmt.add(boundStatement.bind("User B", "12"))
session.execute(batchStmt)
注意：BatchStatement可以容纳65536条语句。学习这个硬的方式。 ： - ）
Note: BatchStatement can hold upto 65536 statement. Learnt this the hard way. :-)
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