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カサンドラ時系列データ、ディスクシーク数を制限する

2016-07-08 3 views
2

私のクエリでディスクシークが頻繁に起こるのに問題があります。私は SS-テーブルを打っていますカサンドラ時系列データ、ディスクシーク数を制限する

CREATE TABLE logs.sessionlink (
    linktype text, 
    link text, 
    "timestamp" timeuuid, 
    sessionid text, 
    PRIMARY KEY ((linktype, link), "timestamp", sessionid) 
);

：このようなテーブルの上に

SELECT sessionid 
FROM sessionlink 
WHERE linktype = 'host' 
    AND link = 'webserver1' 
    AND timestamp > minTimeuuid('2016-07-02 09:00:00') 
    AND timestamp < maxTimeuuid('2016-07-02 10:00:00');

：このようなクエリのために

。クエリがディスク上の非常に多くのSS-テーブルで求められているのはなぜですか？私は手動でsstablemetadataでSSテーブルをチェックして、クエリされた日付が1つのSSテーブルに含まれていることを確認しました（最小タイムスタンプと最大タイムスタンプを見て）。

データを用いて挿入されている：

INSERT INTO sessionlink(sessionid, linktype, link, timestamp) 
VALUES (?, ?, ?, now()) USING TTL ?;

及びテーブルは、日付階層圧縮で圧縮されます。

Spotifyのブログでは、Date Tiered Compaction（https://labs.spotify.com/2014/12/18/date-tiered-compaction/）とその他のリソースについて読んだ後、SS-tableが時間通りに注文されているため、数を最小限に抑えるため、時系列データの読み込みが高速になるという印象を受けました。ディスクの読み込みしかし、それは私のクラスターで見ているものではありません。ここで

（いくつかのキーキャッシュのヒットで、削除行を求めて）、クエリのトレースです：

activity                      | timestamp     | source  | source_elapsed 
-------------------------------------------------------------------------------------------------+----------------------------+---------------+---------------- 
                       Execute CQL3 query | 2016-07-08 12:06:17.333000 | 192.168.4.184 |    0 
              Parsing "The query from above" [SharedPool-Worker-6] | 2016-07-08 12:06:17.335000 | 192.168.4.184 |    72 
      READ message received from /192.168.4.184 [MessagingService-Incoming-/192.168.4.184] | 2016-07-08 12:06:17.335000 | 192.168.4.186 |    23 
                 Preparing statement [SharedPool-Worker-6] | 2016-07-08 12:06:17.336000 | 192.168.4.184 |   236 
          Executing single-partition query on sessionlink [SharedPool-Worker-1] | 2016-07-08 12:06:17.336000 | 192.168.4.186 |    80 
              reading data from /192.168.4.186 [SharedPool-Worker-6] | 2016-07-08 12:06:17.337000 | 192.168.4.184 |   1224 
               Acquiring sstable references [SharedPool-Worker-1] | 2016-07-08 12:06:17.337000 | 192.168.4.186 |    85 
       Sending READ message to /192.168.4.186 [MessagingService-Outgoing-/192.168.4.186] | 2016-07-08 12:06:17.338000 | 192.168.4.184 |   1304 
               Merging memtable tombstones [SharedPool-Worker-1] | 2016-07-08 12:06:17.338000 | 192.168.4.186 |   371 
              Key cache hit for sstable 1168 [SharedPool-Worker-1] | 2016-07-08 12:06:17.339000 | 192.168.4.186 |   1003 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.339000 | 192.168.4.186 |   1007 
              Key cache hit for sstable 1167 [SharedPool-Worker-1] | 2016-07-08 12:06:17.339000 | 192.168.4.186 |   1029 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.343000 | 192.168.4.186 |   1031 
              Key cache hit for sstable 1278 [SharedPool-Worker-1] | 2016-07-08 12:06:17.343000 | 192.168.4.186 |   1965 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.343000 | 192.168.4.186 |   1968 
              Key cache hit for sstable 1277 [SharedPool-Worker-1] | 2016-07-08 12:06:17.344000 | 192.168.4.186 |   1982 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.344000 | 192.168.4.186 |   1984 
              Key cache hit for sstable 1276 [SharedPool-Worker-1] | 2016-07-08 12:06:17.344000 | 192.168.4.186 |   1996 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.345000 | 192.168.4.186 |   1999 
              Key cache hit for sstable 1275 [SharedPool-Worker-1] | 2016-07-08 12:06:17.345000 | 192.168.4.186 |   2011 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.345000 | 192.168.4.186 |   2013 
              Key cache hit for sstable 1274 [SharedPool-Worker-1] | 2016-07-08 12:06:17.346000 | 192.168.4.186 |   2026 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.346000 | 192.168.4.186 |   2027 
              Key cache hit for sstable 1273 [SharedPool-Worker-1] | 2016-07-08 12:06:17.346000 | 192.168.4.186 |   2040 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.346000 | 192.168.4.186 |   2041 
              Key cache hit for sstable 1272 [SharedPool-Worker-1] | 2016-07-08 12:06:17.347000 | 192.168.4.186 |   2053 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.347000 | 192.168.4.186 |   2078 
              Key cache hit for sstable 1271 [SharedPool-Worker-1] | 2016-07-08 12:06:17.347000 | 192.168.4.186 |   2090 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.348000 | 192.168.4.186 |   2092 
                        ... removed some rows to make it fit ... 
REQUEST_RESPONSE message received from /192.168.4.186 [MessagingService-Incoming-/192.168.4.186] | 2016-07-08 12:06:17.402000 | 192.168.4.184 |   68884 
            Processing response from /192.168.4.186 [SharedPool-Worker-2] | 2016-07-08 12:06:17.403000 | 192.168.4.184 |   68953 
              Key cache hit for sstable 1188 [SharedPool-Worker-1] | 2016-07-08 12:06:17.403000 | 192.168.4.186 |   17630 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.403000 | 192.168.4.186 |   17632 
              Key cache hit for sstable 1187 [SharedPool-Worker-1] | 2016-07-08 12:06:17.403000 | 192.168.4.186 |   17647 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.404000 | 192.168.4.186 |   17649 
              Key cache hit for sstable 1186 [SharedPool-Worker-1] | 2016-07-08 12:06:17.404000 | 192.168.4.186 |   17665 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.404000 | 192.168.4.186 |   17666 
              Key cache hit for sstable 1185 [SharedPool-Worker-1] | 2016-07-08 12:06:17.404000 | 192.168.4.186 |   17884 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.405000 | 192.168.4.186 |   17886 
              Key cache hit for sstable 1184 [SharedPool-Worker-1] | 2016-07-08 12:06:17.405000 | 192.168.4.186 |   18098 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.405000 | 192.168.4.186 |   18100 
              Key cache hit for sstable 1183 [SharedPool-Worker-1] | 2016-07-08 12:06:17.405000 | 192.168.4.186 |   18314 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.406000 | 192.168.4.186 |   18317 
              Key cache hit for sstable 1182 [SharedPool-Worker-1] | 2016-07-08 12:06:17.406000 | 192.168.4.186 |   18537 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.406000 | 192.168.4.186 |   18540 
              Key cache hit for sstable 1181 [SharedPool-Worker-1] | 2016-07-08 12:06:17.406000 | 192.168.4.186 |   18754 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.407000 | 192.168.4.186 |   18756 
              Key cache hit for sstable 1180 [SharedPool-Worker-1] | 2016-07-08 12:06:17.407000 | 192.168.4.186 |   18971 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.407000 | 192.168.4.186 |   18974 
              Key cache hit for sstable 1179 [SharedPool-Worker-1] | 2016-07-08 12:06:17.408000 | 192.168.4.186 |   19212 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.408000 | 192.168.4.186 |   19215 
              Key cache hit for sstable 1178 [SharedPool-Worker-1] | 2016-07-08 12:06:17.408000 | 192.168.4.186 |   19434 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.408000 | 192.168.4.186 |   19437 
              Key cache hit for sstable 1177 [SharedPool-Worker-1] | 2016-07-08 12:06:17.409000 | 192.168.4.186 |   19656 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.409000 | 192.168.4.186 |   19658 
              Key cache hit for sstable 1176 [SharedPool-Worker-1] | 2016-07-08 12:06:17.409000 | 192.168.4.186 |   19873 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.409001 | 192.168.4.186 |   19875 
              Key cache hit for sstable 1175 [SharedPool-Worker-1] | 2016-07-08 12:06:17.410000 | 192.168.4.186 |   20093 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.410000 | 192.168.4.186 |   20096 
              Key cache hit for sstable 1174 [SharedPool-Worker-1] | 2016-07-08 12:06:17.410000 | 192.168.4.186 |   20309 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.410000 | 192.168.4.186 |   20311 
              Key cache hit for sstable 1173 [SharedPool-Worker-1] | 2016-07-08 12:06:17.410000 | 192.168.4.186 |   20537 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.411000 | 192.168.4.186 |   20539 
              Key cache hit for sstable 1172 [SharedPool-Worker-1] | 2016-07-08 12:06:17.411000 | 192.168.4.186 |   20762 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.411000 | 192.168.4.186 |   20765 
              Key cache hit for sstable 1171 [SharedPool-Worker-1] | 2016-07-08 12:06:17.412000 | 192.168.4.186 |   20985 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.412000 | 192.168.4.186 |   20987 
              Key cache hit for sstable 1170 [SharedPool-Worker-1] | 2016-07-08 12:06:17.412000 | 192.168.4.186 |   21212 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.412000 | 192.168.4.186 |   21214 
              Key cache hit for sstable 1169 [SharedPool-Worker-1] | 2016-07-08 12:06:17.413000 | 192.168.4.186 |   21230 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.413000 | 192.168.4.186 |   21232 
              Key cache hit for sstable 1166 [SharedPool-Worker-1] | 2016-07-08 12:06:17.413000 | 192.168.4.186 |   21497 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.414000 | 192.168.4.186 |   21501 
              Key cache hit for sstable 1165 [SharedPool-Worker-1] | 2016-07-08 12:06:17.414000 | 192.168.4.186 |   21928 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.414000 | 192.168.4.186 |   21930 
              Key cache hit for sstable 1164 [SharedPool-Worker-1] | 2016-07-08 12:06:17.414001 | 192.168.4.186 |   22476 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.415000 | 192.168.4.186 |   22479 
              Key cache hit for sstable 1163 [SharedPool-Worker-1] | 2016-07-08 12:06:17.415000 | 192.168.4.186 |   22494 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.415000 | 192.168.4.186 |   22496 
              Key cache hit for sstable 1162 [SharedPool-Worker-1] | 2016-07-08 12:06:17.415000 | 192.168.4.186 |   23103 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.415000 | 192.168.4.186 |   23107 
              Key cache hit for sstable 1161 [SharedPool-Worker-1] | 2016-07-08 12:06:17.416000 | 192.168.4.186 |   23124 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.416000 | 192.168.4.186 |   23126 
              Key cache hit for sstable 1160 [SharedPool-Worker-1] | 2016-07-08 12:06:17.416000 | 192.168.4.186 |   23753 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.417000 | 192.168.4.186 |   23757 
              Key cache hit for sstable 1159 [SharedPool-Worker-1] | 2016-07-08 12:06:17.417000 | 192.168.4.186 |   23771 
          Seeking to partition indexed section in data file [SharedPool-Worker-1] | 2016-07-08 12:06:17.417000 | 192.168.4.186 |   23773 
                       Request complete | 2016-07-08 12:06:17.402317 | 192.168.4.184 |   69317

出典

2016-07-08 Simon Lindberg

+1

ブルームフィルタは、レンジスキャンを実行するときには使用されません。それゆえ、すべてのssテーブルが参照されます。 https://docs.datastax.com/en/cassandra/2.1/cassandra/2.1/cassandra/operations/ops_tuning_bloom_filters_c.html –

+0

私はデフォルトの 'bloom_filter_fp_chance'を0.01（DTC用）としていますが、それを減らそうとします。 –

答えて

0

https://academy.datastax.com/resources/getting-started-time-series-data-modeling

これはカサンドラの日付を使用しての良い例です。私はあなたがどのようにテーブルをモデリングしているかに問題があると信じています。タイムスタンプをパーティションキーに移動すると、Cassandraは検索するテーブルをよりよく知ることができます。代わりに（linktype、link）でデータを注文する場合は、データが格納されているすべての領域を検索する必要があります。

つまり、プライマリキーを（linktype 、リンク、 "タイムスタンプ"）、セッションID）。

出典

2016-07-08 19:57:53

+0

"EQとINの関係のみがパーティションキーでサポートされています"ので、提案するスキーマのタイムスタンプでスライシングクエリを実行することはできません。 しかし、私はこの記事を読んできました。私は、パターン化されたパーティショニングキーを除いて、パターン例1にかなり従っています。それは私の問題と関係がありますか？パーティションキーとして単一のIDだけを使用するとパフォーマンスが向上するはずですか？このように '（linkid、" timestamp "、sessionid）'。 –

+0

記事を引用する。 _ 2つの日付間のデータを検索する範囲クエリ。それは、ディスクからのデータのシーケンスを読み込みますので、これはまた、スライスとして知られています：weatherstation_id =「1234ABCD」 とEVENT_TIME>「2013年4月3日午前7時01分〇〇秒 " 温度 FROM SELECT温度 をAND event_time <'2013-04-03 07:04:00'; _私はそれをどのように読んでいるかに応じて、日付範囲でスライスを作成できるようです。 –

+0

あなたの2番目の質問に答えてください。私はあなたが単一の値のパーティションキーでより良いパフォーマンスを期待できるとは思わない、あなたはちょうど少ないデータを格納するでしょう。 –

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