orc文件的读写及整合hive

还是先说下背景。

为啥想到学习orc文件的读写呢？ 我们create table的时候stored as orc就好了呀，读写有什么作用呢？

1.使用datax hdfsreader的时候有时候hdfswriter的写速度过慢，针对的我之前的splitpk，可以一定程度减少这个耗时，但是他慢就是慢，就好像a干活很慢，你现在用10个a干活，比之前肯定快，但是还是慢。

2.了解orc文件的读写，可以有效的排查问题，例如，decimal字段精度不对，怎么调整，文件大小不是128M怎么做？

3.更好的吹牛b。

先说下注意事项hive写orc文件是有两个包的。

要注意，两者都可以写orc但是有些些的差别。 

 
 org.apache.hadoop
 hadoop-client
 2.7.7
 
 
 org.apache.orc
 orc-core
 1.5.4
 

如果上面的不行引用 hive-exec.jar 试下。我引用的有点多分不清了。

以下代码 只用改下main方法的路径，可以直接跑的。

package com.chenchi.learning.fileformat.orc;

/**
 * 
 * org.apache.hadoop
 * hadoop-client
 * 2.7.7
 * 
 * 
 * org.apache.orc
 * orc-core
 * 1.5.4
 * 
 * -----------------------------------
 * ©著作权归作者所有：来自51CTO博客作者铁头乔的博客的原创作品，请联系作者获取转载授权，否则将追究法律责任
 * ORC 文件层 API 读写  参考了这个的加以拓展
 * https://blog.51cto.com/u_15352899/3746656
 */

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.common.type.HiveDecimal;
import org.apache.hadoop.hive.ql.exec.vector.*;
import org.apache.hadoop.hive.ql.io.sarg.PredicateLeaf;
import org.apache.hadoop.hive.ql.io.sarg.SearchArgumentFactory;
import org.apache.hadoop.hive.serde2.io.HiveDecimalWritable;
import org.apache.orc.*;

import java.io.File;
import java.io.IOException;
import java.math.BigDecimal;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;

public class ReadAndWriteOrcTest {

    public static void main(String[] args) throws IOException {
        ReadAndWriteOrcTest writeOrc = new ReadAndWriteOrcTest();
        writeOrc.writeOrc("D:\\install\\code\\learning\\bigdata_learining\\src\\main\\resources\\out\\my-file.orc");
        writeOrc.readOrc("D:\\install\\code\\learning\\bigdata_learining\\src\\main\\resources\\out\\my-file.orc");
    }

    private void writeOrc(String path) throws IOException {
        File file = new File(path);
        if (file.exists()) file.delete();
        Configuration conf = new Configuration();
        TypeDescription schema = TypeDescription.createStruct()
                .addField("long_value", TypeDescription.createLong())
                .addField("double_value", TypeDescription.createDouble())
                .addField("boolean_value", TypeDescription.createBoolean())
                .addField("string_value", TypeDescription.createString())
                .addField("decimal_value",TypeDescription.createDecimal().withScale(18))
                .addField("date_value",TypeDescription.createTimestamp())
                .addField("timestamp_value",TypeDescription.createTimestamp());
        Writer writer = OrcFile.createWriter(new Path(path),
                OrcFile.writerOptions(conf)
                        .setSchema(schema)
                        .stripeSize(67108864)
                        .bufferSize(64 * 1024)
                        .blockSize(128 * 1024 * 1024)
                        .rowIndexStride(10000)
                        .blockPadding(true)
                        .compress(CompressionKind.ZLIB));

        //根据 列数和默认的1024 设置创建一个batch
        VectorizedRowBatch batch = schema.createRowBatch();
        LongColumnVector longVector = (LongColumnVector) batch.cols[0];
        DoubleColumnVector doubleVector = (DoubleColumnVector) batch.cols[1];
        LongColumnVector booleanVector = (LongColumnVector) batch.cols[2];
        BytesColumnVector stringVector = (BytesColumnVector) batch.cols[3];
        DecimalColumnVector decimalVector = (DecimalColumnVector) batch.cols[4];
        TimestampColumnVector dateVector = (TimestampColumnVector) batch.cols[5];
        TimestampColumnVector timestampVector = (TimestampColumnVector) batch.cols[6];
        for (int r = 0; r < 10; ++r) {
            int row = batch.size++;
            longVector.vector[row] = r;
            doubleVector.vector[row] = r;
            booleanVector.vector[row] = r %2;
            stringVector.setVal(row, UUID.randomUUID().toString().getBytes());
            BigDecimal bigDecimal = new BigDecimal((double) r / 3).setScale(18,BigDecimal.ROUND_DOWN);
            HiveDecimal hiveDecimal = HiveDecimal.create(bigDecimal).setScale(18);
            decimalVector.set(row, hiveDecimal);
            long time = new Date().getTime();
            Timestamp timestamp = new Timestamp(time);
            dateVector.set(row,timestamp);
            timestampVector.set(row,timestamp);

            if (batch.size == batch.getMaxSize()) {
                writer.addRowBatch(batch);
                batch.reset();
            }
        }
        if (batch.size != 0) {
            writer.addRowBatch(batch);
            batch.reset();
        }
        writer.close();
    }


    private  void readOrc(String path) throws IOException {
        Configuration conf = new Configuration();

        TypeDescription readSchema = TypeDescription.createStruct()
                .addField("long_value", TypeDescription.createLong())
                .addField("double_value", TypeDescription.createDouble())
                .addField("boolean_value", TypeDescription.createBoolean())
                .addField("string_value", TypeDescription.createString())
                        .addField("decimal_value",TypeDescription.createDecimal().withScale(18))
                        .addField("date_value",TypeDescription.createTimestamp())
                        .addField("timestamp_value",TypeDescription.createTimestamp()
                        );


        Reader reader = OrcFile.createReader(new Path(path),
                OrcFile.readerOptions(conf));
        OrcFile.WriterVersion writerVersion = reader.getWriterVersion();
        System.out.println("writerVersion="+writerVersion);
        Reader.Options readerOptions = new Reader.Options()
                .searchArgument(
                        SearchArgumentFactory
                                .newBuilder()
                                .between("long_value", PredicateLeaf.Type.LONG, 0L,1024L)
                                .build(),
                        new String[]{"long_value"}
                );

        RecordReader rows = reader.rows(readerOptions.schema(readSchema));

        VectorizedRowBatch batch = readSchema.createRowBatch();
        int count=0;
        while (rows.nextBatch(batch)) {
            LongColumnVector longVector = (LongColumnVector) batch.cols[0];
            DoubleColumnVector doubleVector = (DoubleColumnVector) batch.cols[1];
            LongColumnVector booleanVector = (LongColumnVector) batch.cols[2];
            BytesColumnVector stringVector = (BytesColumnVector) batch.cols[3];
            DecimalColumnVector decimalVector = (DecimalColumnVector) batch.cols[4];
            TimestampColumnVector dateVector = (TimestampColumnVector) batch.cols[5];
            TimestampColumnVector timestampVector = (TimestampColumnVector) batch.cols[6];
            count++;
            if (count==1){
                for(int r=0; r < batch.size; r++) {
                    long longValue = longVector.vector[r];
                    double doubleValue = doubleVector.vector[r];
                    boolean boolValue = booleanVector.vector[r] != 0;
                    String stringValue = stringVector.toString(r);
                    HiveDecimalWritable hiveDecimalWritable = decimalVector.vector[r];
                    long time1 = dateVector.getTime(r);
                    Date date = new Date(time1);
                    String format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(date);
                    long time = timestampVector.time[r];
                    int nano = timestampVector.nanos[r];
                    Timestamp timestamp = new Timestamp(time);
                    timestamp.setNanos(nano);
                    System.out.println(longValue + ", " + doubleValue + ", " + boolValue + ", " + stringValue+", "+hiveDecimalWritable.getHiveDecimal().toFormatString(18)+", "+format+", "+timestamp);

                }
            }

        }
        System.out.println("count="+count);
        rows.close();
    }

}

打印结果 可以看到decimal保留了18位小数，date日期ok， timestamp的毫秒也ok

生成的文件

 ————————————————————————————————————————

整合hive

 create table test.orc_read(
 long_value bigint ,
 double_value double ,
 boolean_value boolean,
 string_value string,
 decimal_value decimal(38,18),
 date_value date,
 timestamp_value timestamp
 )
 stored as orc;

 

把写好的文件放到表的指定目录下。

然后是见证奇迹的时候了，直接select * 可以看到orc文件内容。一切ok ---其实不ok 有问题。

 紧接着我们可以改造datax的hdfsreader。。

 其实就是把这一段换成我们的writer就行，而且我们的write里有个batch是可以控制写出文件的速度的。