Cassandra 删除键空间时连接超时

删除键空间时遇到问题

所讨论的键空间有4个与此表类似的表：

CREATE KEYSPACE demo WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'}  AND durable_writes = false;

CREATE TABLE demo.t1 (
    t11 int,
    t12 timeuuid,
    t13 int,
    t14 text,
    t15 text,
    t16 boolean,
    t17 boolean,
    t18 int,
    t19 timeuuid,
    t110 text,
    PRIMARY KEY (t11, t12)
) WITH CLUSTERING ORDER BY (t13 DESC)
    AND bloom_filter_fp_chance = 0.01
    AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
    AND comment = ''
    AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold': '32', 'min_threshold': '4'}
    AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND crc_check_chance = 1.0
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 864000
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair_chance = 0.0
    AND speculative_retry = '99PERCENTILE';
CREATE INDEX t1_idx ON demo.t1 (t14);
CREATE INDEX t1_deleted_idx ON demo.t2 (t15);

当我想使用以下命令删除键空间时：

    Session session = cluster.connect();
    PreparedStatement prepared = session.prepare("drop keyspace if exists " + schemaName);
    BoundStatement bound = prepared.bind();
    session.execute(bound);

然后查询超时或执行时间超过10秒，即使表为空：

---

我在多台机器上试过，结果是一样的。我用的是卡桑德拉3.9。使用cqlsh也会发生类似的情况。我知道我可以增加cassandra.yaml文件中的读取超时，但如何使其下降更快？另一件事是，如果我连续执行两个请求，第一个请求会超时，第二个请求会很快通过。

尝试在增加超时的情况下运行它：

cqlsh-请求超时=3600秒，默认为10秒

在驾驶员级别上也应该有相同的设置。查看此链接中的超时会话：

---

增加超时只会隐藏问题，这通常是个坏主意。看看这个答案：

增加超时时间只会隐藏问题，通常是个坏主意。看看这个答案：

com.datastax.driver.core.exceptions.OperationTimedOutException: [/192.168.0.1:9042] Timed out waiting for server response
        at com.datastax.driver.core.exceptions.OperationTimedOutException.copy(OperationTimedOutException.java:44)
        at com.datastax.driver.core.exceptions.OperationTimedOutException.copy(OperationTimedOutException.java:26)
        at com.datastax.driver.core.DriverThrowables.propagateCause(DriverThrowables.java:37)
        at com.datastax.driver.core.DefaultResultSetFuture.getUninterruptibly(DefaultResultSetFuture.java:245)
        at com.datastax.driver.core.AbstractSession.execute(AbstractSession.java:64)
        at com.datastax.driver.core.AbstractSession.execute(AbstractSession.java:39)