Question

我希望从特定表中删除大量行

我做了以下步骤： 1）为表设置gc_grace_seconds = 0 2）删除了大量的行~100万 3）Ran ./nodetool compact keyspace_name table_name

然而，当我运行nodetool compact（步骤3）时，没有任何反应。它不会开始压缩。由于墓碑数量很多，我的大部分请求现在都会超时。

该表格具有以下设置：

AND bloom_filter_fp_chance = 0.001
    AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
    AND comment = ''
    AND compaction = {'tombstone_threshold': '0.2', 'tombstone_compaction_interval': '86400', 'class': 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy'}
    AND compression = {'sstable_compression': 'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND dclocal_read_repair_chance = 0.1
    AND default_time_to_live = 0
    AND gc_grace_seconds = 0
    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 = '99.0PERCENTILE';

我希望压缩并摆脱墓碑，这样我才能真正摆脱不需要的数据。

我的群集中有两个节点，复制因子为2 由于我做了删除，两者之间的大小差异有所增加。相差约700MB。我正在使用dsc-cassandra-2.1.10

cfstats如下所示

Keyspace: keyspace1
        Read Count: 16316
        Read Latency: 12.23892982348615 ms.
        Write Count: 11078808
        Write Latency: 0.6955001765532899 ms.
        Pending Flushes: 0
                Table: table1
                SSTable count: 92
                SSTables in each level: [1, 4, 38, 49, 0, 0, 0, 0, 0]
                Space used (live): 38247164244
                Space used (total): 38247164244
                Space used by snapshots (total): 26692664189
                Off heap memory used (total): 14695952
                SSTable Compression Ratio: 0.32499125289530584
                Number of keys (estimate): 2788
                Memtable cell count: 16632
                Memtable data size: 1839846
                Memtable off heap memory used: 0
                Memtable switch count: 93
                Local read count: 16316
                Local read latency: 12.239 ms
                Local write count: 11078808
                Local write latency: 0.696 ms
                Pending flushes: 0
                Bloom filter false positives: 331
                Bloom filter false ratio: 0.00000
                Bloom filter space used: 10960
                Bloom filter off heap memory used: 10224
                Index summary off heap memory used: 3672
                Compression metadata off heap memory used: 14682056
                Compacted partition minimum bytes: 216
                Compacted partition maximum bytes: 3449259151
                Compacted partition mean bytes: 25823653
                Average live cells per slice (last five minutes): 405.3014160485502
                Maximum live cells per slice (last five minutes): 5002.0
                Average tombstones per slice (last five minutes): 0.0
                Maximum tombstones per slice (last five minutes): 0.0

Answer 1

压缩策略决定了nodetool compact的行为，并且版本之间的api存在细微差别

http://docs.datastax.com/en/archived/cassandra/3.x/cassandra/tools/toolsCompact.html VS https://docs.datastax.com/en/cassandra/2.1/cassandra/tools/toolsCompact.html

删除数据和逻辑删除：

将压缩策略切换为SizeTieredComapction
运行一个主要的压缩，它将生成一个sstable（不会保留墓碑覆盖的墓碑/数据）
将压缩切换回LeveledCompaction

执行主要压缩并在压缩策略之间切换是一项IO密集型操作 - 请考虑到这一点。

Cassandra nodetool compact没有任何反应

1 个答案: