现象:
+----------+-------+--------+-----+-----+-----+----+----+------+---------+-------+--------+--------+------------+
|totalCount|January|February|March|April| May|June|July|August|September|October|November|December|totalMileage|
+----------+-------+--------+-----+-----+-----+----+----+------+---------+-------+--------+--------+------------+
| 33808| 0| 0| 0| 0|33798| 0| 0| 0| 0| 0| 0| 0| 79995.0|
+----------+-------+--------+-----+-----+-----+----+----+------+---------+-------+--------+--------+------------+
当前表预分区10个
按照当月数据看,当前测试表中总数量是:33798
hbase的总数量也是:33798
神奇的地方:使用sparkSQL对接hbase查询的数量是:33808
当时的sql语句是:select count(1) from orderData
很神奇,因为通过sql查询后,总数据多了10条
============================================================
原因:
这里设置了hbase SCAN_BATCHSIZE这个值,会设置scan的batchsize。这个设置的文档是这样说的:
Set the maximum number of values to return for each call to next()
之前一直以为这里是设置一次读取多少行,其实values貌似是读取多少列,并且开启了这个值会导致hbase scan时返回一行的部分结果;
于是将这个设置注释掉,程序即可正常运行
进一步的,我们从hbase端代码看看这个设置。hbase的scan会两个成员变量:
private boolean allowPartialResults = false;
private int batch = -1;
allowPartialResult这个很明显就是会返回部分结果的设置,那么这个batch呢?setBatch()时并不会设置allowPartialResult。但是在Scan的getResultsToAddToCache()函数中,如果batch值大于0,会设置isBatch=true。之后会有这段代码:
// If the caller has indicated in their scan that they are okay with seeing partial results,
// then simply add all results to the list. Note that since scan batching also returns results
// for a row in pieces we treat batch being set as equivalent to allowing partials. The
// implication of treating batching as equivalent to partial results is that it is possible
// the caller will receive a result back where the number of cells in the result is less than
// the batch size even though it may not be the last group of cells for that row.
if (allowPartials || isBatchSet) {
addResultsToList(resultsToAddToCache, resultsFromServer, ,
(null == resultsFromServer ? : resultsFromServer.length));
return resultsToAddToCache;
}
之前错误代码:
TableInputFormat.SCAN_BATCHSIZE
lazy val buildScan = { val hbaseConf = HBaseConfiguration.create()
hbaseConf.set("hbase.zookeeper.quorum", GlobalConfigUtils.hbaseQuorem)
hbaseConf.set(TableInputFormat.INPUT_TABLE, hbaseTableName)
hbaseConf.set(TableInputFormat.SCAN_COLUMNS, queryColumns)
hbaseConf.set(TableInputFormat.SCAN_ROW_START, startRowKey)
hbaseConf.set(TableInputFormat.SCAN_ROW_STOP, endRowKey)
hbaseConf.set(TableInputFormat.SCAN_BATCHSIZE , "")//TODO 此处导致查询数据不一致
hbaseConf.set(TableInputFormat.SCAN_CACHEDROWS , "")
hbaseConf.set(TableInputFormat.SHUFFLE_MAPS , "") val hbaseRdd = sqlContext.sparkContext.newAPIHadoopRDD(
hbaseConf,
classOf[org.apache.hadoop.hbase.mapreduce.TableInputFormat],
classOf[org.apache.hadoop.hbase.io.ImmutableBytesWritable],
classOf[org.apache.hadoop.hbase.client.Result]
) val rs: RDD[Row] = hbaseRdd.map(tuple => tuple._2).map(result => { var values = new ArrayBuffer[Any]()
hbaseTableFields.foreach { field =>
values += Resolver.resolve(field, result)
}
Row.fromSeq(values.toSeq)
})
rs
}
解决:
去掉TableInputFormat.SCAN_BATCHSIZE的设置即可
去掉后的查询结果:
+----------+-------+--------+-----+-----+-----+----+----+------+---------+-------+--------+--------+------------+
|totalCount|January|February|March|April| May|June|July|August|September|October|November|December|totalMileage|
+----------+-------+--------+-----+-----+-----+----+----+------+---------+-------+--------+--------+------------+
| 33798| 0| 0| 0| 0|33798| 0| 0| 0| 0| 0| 0| 0| 79995.0|
+----------+-------+--------+-----+-----+-----+----+----+------+---------+-------+--------+--------+------------+
问题解决~