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This link說:爲什麼在Cassandra中BuiltStatement比BoundStatement更有效?
BoundStatement:通過結合值來一份聲明中獲得的。通常用於經常執行的查詢,具有不同的值。
BuiltStatement:使用QueryBuilder DSL構建的語句。它可以像一個簡單的語句直接執行,或準備。
所以在我看來,BuiltStatement等於BoundStatement。 Howerver,就我而言,我發現BuiltStatement顯然比BoundStatement更高效。爲什麼發生這種情況?
public static void main(String[] args) {
Data mc = null;
ResultSet results = null;
PK pk = null;
CassandraData dao = new CassandraData();
Session session = dao.getSession();
long start, end;
long start0 = System.currentTimeMillis();
// PreparedStatement prepared = session.prepare(
// "select * from test where E=? and D=? and M=?");
Statement statement = null;
logger.info("Start:");
for (int i = 0; i < 100; i++) {
pk = ValidData.getOnePk();
start = System.currentTimeMillis();
// statement = prepared.bind(pk.E, pk.D, pk.M);
// statement.setReadTimeoutMillis(100000);
statement = getSelect(pk);
results = session.execute(statement);
end = System.currentTimeMillis();
logger.info("Show OneKb:" + (end - start)/1000.0 + "s.");
}
long end0 = System.currentTimeMillis();
logger.info("Show OneKb Average:" + (end0 - start0)/1000.0/100 + "s/OneKb.");
}
private static Statement getSelect(PK pk) {
Select ss = QueryBuilder.select().from("test");
ss.setConsistencyLevel(com.datastax.driver.core.ConsistencyLevel.ONE);
ss.where(QueryBuilder.eq("E", pk.E))
.and(QueryBuilder.eq("D", pk.D))
.and(QueryBuilder.eq("M", pk.M)).limit(1)
.setReadTimeoutMillis(100 * 1000);
return ss;
}
我跑這種情況下,100倍和BoundStatement
的平均時間爲1.316s和BuiltStatement
的平均時間爲0.199s。