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hive matestore假死 validate hive metastore schema

  上次写了hive metastore的partition的生命周期,但是简略概括了下alter_partition的操作,这里补一下alter_partition,因为随着项目的深入,发现它涉及的地方较多,比如insert into 时如果路径存在情况下会调用alter_partition,调用insert overwrite语句时,也会调用该方法,

  入口依旧是Hive.java这个类:

1   public void alterPartition(String dbName, String tblName, Partition newPart)
 2       throws InvalidOperationException, HiveException {
 3     try {
 4       // Remove the DDL time so that it gets refreshed
 5       if (newPart.getParameters() != null) {
 6         newPart.getParameters().remove(hive_metastoreConstants.DDL_TIME);
 7       }
 8       newPart.checkValidity();
 9       getMSC().alter_partition(dbName, tblName, newPart.getTPartition());
10 
11     } catch (MetaException e) {
12       throw new HiveException("Unable to alter partition. " + e.getMessage(), e);
13     } catch (TException e) {
14       throw new HiveException("Unable to alter partition. " + e.getMessage(), e);
15     }
16   }

  随后通过HiveMetaStoreClient调用alter_partition请求服务端,传入的参数中包含新的partition,然后服务端调用了rename_partition方法,详细不再说了,上一篇大体的也说明了,这里直接从alterHandler.alterPartition进行partition的更改开始。

1  public Partition alterPartition(final RawStore msdb, Warehouse wh, final String dbname,
  2       final String name, final List<String> part_vals, final Partition new_part)
  3       throws InvalidOperationException, InvalidObjectException, AlreadyExistsException,
  4       MetaException {
  5     boolean success = false;
  6 
  7     Path srcPath = null;
  8     Path destPath = null;
  9     FileSystem srcFs = null;
 10     FileSystem destFs = null;
 11     Partition oldPart = null;
 12     String oldPartLoc = null;
 13     String newPartLoc = null;
 14 
 15     // Set DDL time to now if not specified
 16     if (new_part.getParameters() == null ||
 17         new_part.getParameters().get(hive_metastoreConstants.DDL_TIME) == null ||
 18         Integer.parseInt(new_part.getParameters().get(hive_metastoreConstants.DDL_TIME)) == 0) {
 19       new_part.putToParameters(hive_metastoreConstants.DDL_TIME, Long.toString(System
 20           .currentTimeMillis() / 1000));
 21     }
 22 
 23     Table tbl = msdb.getTable(dbname, name);
 24     //alter partition
 25     if (part_vals == null || part_vals.size() == 0) {
 26       try {
 27         oldPart = msdb.getPartition(dbname, name, new_part.getValues());
 28         if (MetaStoreUtils.requireCalStats(hiveConf, oldPart, new_part, tbl)) {
 29           MetaStoreUtils.updatePartitionStatsFast(new_part, wh, false, true);
 30         }
 31         updatePartColumnStats(msdb, dbname, name, new_part.getValues(), new_part);
 32         msdb.alterPartition(dbname, name, new_part.getValues(), new_part);
 33       } catch (InvalidObjectException e) {
 34         throw new InvalidOperationException("alter is not possible");
 35       } catch (NoSuchObjectException e){
 36         //old partition does not exist
 37         throw new InvalidOperationException("alter is not possible");
 38       }
 39       return oldPart;
 40     }
      。。。。。。

  从代码中我们可以看到:

  1、通过Table tbl = msdb.getTable(dbname, name); get到该表的整个元数据的封装信息。

  2、随后oldPart = msdb.getPartition(dbname, name, new_part.getValues());,通过dbName、tableName、Values获取partition的元数据信息,Values便是新的partition分区结构eg:(2017-09-11),随后调用MetaStoreUtils.requireCalStats(hiveConf, oldPart, new_part, tbl),进行元数据存在校验,如果不存在,则调用updatePartitionStatsFast进行更新(这里就不再详细说明,因为我不知道里面StatsSetupConst的配置参数是干嘛的哈哈哈哈哈~尴尬~一步步来嘛)

  3、随后调用了updatePartColumnStats方法,进行物理partition地址的更新,我们一步一步看,代码如下:

1   private void updatePartColumnStats(RawStore msdb, String dbName, String tableName,
 2       List<String> partVals, Partition newPart) throws MetaException, InvalidObjectException {
 3     dbName = HiveStringUtils.normalizeIdentifier(dbName);
 4     tableName = HiveStringUtils.normalizeIdentifier(tableName);
 5     String newDbName = HiveStringUtils.normalizeIdentifier(newPart.getDbName());
 6     String newTableName = HiveStringUtils.normalizeIdentifier(newPart.getTableName());
 7 
 8     Table oldTable = msdb.getTable(dbName, tableName);
 9     if (oldTable == null) {
10       return;
11     }
12 
13     try {
14       String oldPartName = Warehouse.makePartName(oldTable.getPartitionKeys(), partVals);
15       String newPartName = Warehouse.makePartName(oldTable.getPartitionKeys(), newPart.getValues());
16       if (!dbName.equals(newDbName) || !tableName.equals(newTableName)
17           || !oldPartName.equals(newPartName)) {
18         msdb.deletePartitionColumnStatistics(dbName, tableName, oldPartName, partVals, null);
19       } else {
20         Partition oldPartition = msdb.getPartition(dbName, tableName, partVals);
21         if (oldPartition == null) {
22           return;
23         }
24         if (oldPartition.getSd() != null && newPart.getSd() != null) {
25         List<FieldSchema> oldCols = oldPartition.getSd().getCols();
26           if (!MetaStoreUtils.areSameColumns(oldCols, newPart.getSd().getCols())) {
27             updatePartColumnStatsForAlterColumns(msdb, oldPartition, oldPartName, partVals, oldCols, newPart);
28           }
29         }
30       }
31     } catch (NoSuchObjectException nsoe) {
32       LOG.debug("Could not find db entry." + nsoe);
33       //ignore
34     } catch (InvalidInputException iie) {
35       throw new InvalidObjectException("Invalid input to update partition column stats." + iie);
36     }
37   }

  5、Table oldTable = msdb.getTable(dbName, tableName);这里获取oldTable的所有元数据信息,随后通过makePartName拼接新老partition的partName(eg:/dt=2017-09-11/hour/1)用于新老partition的hdfs的路径对比,因为alterPartition操作,可能是通过alter table、table rename等操作执行的,所以如果老的dbName、tableName、以及partition Name与新的不同,那么就需要将元数据中类似于meta_partition的数据清空。随后通过客户端重新创建partition。

  6、如果是相同的,那么说明修改是partition的列信息,通过MetaStoreUtils.areSameColumns(oldCols, newPart.getSd().getCols())进行校验(内部方法不再把代码贴出来了)

  7、调用updatePartColumnStatsForAlterColumns开始进行column的更新,这里面代码还是要贴出来一起玩一下:

private void updatePartColumnStatsForAlterColumns(RawStore msdb, Partition oldPartition,
      String oldPartName, List<String> partVals, List<FieldSchema> oldCols, Partition newPart)
          throws MetaException, InvalidObjectException {
    String dbName = oldPartition.getDbName();
    String tableName = oldPartition.getTableName();
    try {
      List<String> oldPartNames = Lists.newArrayList(oldPartName);
      List<String> oldColNames = new ArrayList<String>(oldCols.size());
      for (FieldSchema oldCol : oldCols) {
        oldColNames.add(oldCol.getName());
      }
      List<FieldSchema> newCols = newPart.getSd().getCols();
      List<ColumnStatistics> partsColStats = msdb.getPartitionColumnStatistics(dbName, tableName,
          oldPartNames, oldColNames);
      assert (partsColStats.size() <= 1);
      for (ColumnStatistics partColStats : partsColStats) { //actually only at most one loop
        List<ColumnStatisticsObj> statsObjs = partColStats.getStatsObj();
        for (ColumnStatisticsObj statsObj : statsObjs) {
          boolean found =false;
          for (FieldSchema newCol : newCols) {
            if (statsObj.getColName().equals(newCol.getName())
                && statsObj.getColType().equals(newCol.getType())) {
              found = true;
              break;
            }
          }
          if (!found) {
            msdb.deletePartitionColumnStatistics(dbName, tableName, oldPartName, partVals,
                statsObj.getColName());
          }
        }
      }
    } catch (NoSuchObjectException nsoe) {
      LOG.debug("Could not find db entry." + nsoe);
      //ignore
    } catch (InvalidInputException iie) {
      throw new InvalidObjectException
      ("Invalid input to update partition column stats in alter table change columns" + iie);
    }
  }

  这里可以看到,它查询元数据并封装了一个ColumnStatistics对象,这个对象主要封装了tableName、PartName、colName等信息,随后将其取出来使新老ColName进行对比,注意,这里是对colName以及type进行对比,如果不同,则删除老的colName信息。

  好的,现在相当于将所有old的不一致的数据删除,下来我们回到之前的alterPartition中来,随后调用alterPartition(dbname, name, new_part.getValues(), new_part)将新的partition数据注册到元数据中。以上,只是当调用rename_partition时,par_vals为null的情况下,对oldPart所进行的操作,那么不为null时呢?是不是很绝望?我们慢慢折磨哈哈。。。

  8、在par_vals不为null的情况下,会通过dbName、tableName、以及part_vals进行oldPart的查找并进行校验。

  9、对表的类型进行判断,如果该表为内部表,则将原有的oldPart的table所在storage路径,也就是hdfs路径赋给newPart,这里注意的是不是partition的location路径,是storage的location路径。随之调用deletePartitionColumnStatistics直接删除原有partition meta信息。

  10、如果该表为外部表,其实就是进行check,随后删除元数据meta(其实是中间有没懂得地方哈哈哈。。而且太晚了,后续补上....)代码如下:

1        try {
 2           destPath = new Path(wh.getTablePath(msdb.getDatabase(dbname), name),
 3             Warehouse.makePartName(tbl.getPartitionKeys(), new_part.getValues()));
 4           destPath = constructRenamedPath(destPath, new Path(new_part.getSd().getLocation()));
 5         } catch (NoSuchObjectException e) {
 6           LOG.debug(e);
 7           throw new InvalidOperationException(
 8             "Unable to change partition or table. Database " + dbname + " does not exist"
 9               + " Check metastore logs for detailed stack." + e.getMessage());
10         }
11         if (destPath != null) {
12           newPartLoc = destPath.toString();
13           oldPartLoc = oldPart.getSd().getLocation();
14 
15           srcPath = new Path(oldPartLoc);
16 
17           LOG.info("srcPath:" + oldPartLoc);
18           LOG.info("descPath:" + newPartLoc);
19           srcFs = wh.getFs(srcPath);
20           destFs = wh.getFs(destPath);
21           // check that src and dest are on the same file system
22           if (!FileUtils.equalsFileSystem(srcFs, destFs)) {
23             throw new InvalidOperationException("table new location " + destPath
24               + " is on a different file system than the old location "
25               + srcPath + ". This operation is not supported");
26           }
27           try {
28             srcFs.exists(srcPath); // check that src exists and also checks
29             if (newPartLoc.compareTo(oldPartLoc) != 0 && destFs.exists(destPath)) {
30               throw new InvalidOperationException("New location for this table "
31                 + tbl.getDbName() + "." + tbl.getTableName()
32                 + " already exists : " + destPath);
33             }
34           } catch (IOException e) {
35             throw new InvalidOperationException("Unable to access new location "
36               + destPath + " for partition " + tbl.getDbName() + "."
37               + tbl.getTableName() + " " + new_part.getValues());
38           }
39           new_part.getSd().setLocation(newPartLoc);
40           if (MetaStoreUtils.requireCalStats(hiveConf, oldPart, new_part, tbl)) {
41             MetaStoreUtils.updatePartitionStatsFast(new_part, wh, false, true);
42           }
43           String oldPartName = Warehouse.makePartName(tbl.getPartitionKeys(), oldPart.getValues());
44           try {
45             //existing partition column stats is no longer valid, remove
46             msdb.deletePartitionColumnStatistics(dbname, name, oldPartName, oldPart.getValues(), null);

  总的来说,会发现调用alterPartition的时候,并没有与物理操作耦合在一起,只是对ColumnStats元数据进行查找更新删除等动作,但是真正在调用alterPartition时,对于元数据本身,其实是更新了该partition的sd信息,以及重要的location.

  相关的操作还是蛮多的,这里知识大致的分析了下,边看源码边写, 如有错误之处,还望各位大神之处,谢谢~ 碎觉~~明天去作死的干活咯~ 

  


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