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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4184) Drill does not support Parquet DECIMAL values in variable length BINARY fields
Date Sun, 06 Mar 2016 21:23:40 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15182339#comment-15182339
] 

ASF GitHub Bot commented on DRILL-4184:
---------------------------------------

Github user daveoshinsky commented on the pull request:

    https://github.com/apache/drill/pull/372#issuecomment-192999951
  
    Regarding the overall intent of the fix, as the "TODO" comment on decimalLengths implies,
it's intended only as a short-term fix.  More long-term, I would suggest that decimal values
should be stored in a VariableWidthVector (which was assumed by VarLenghValuesColumn, hence
the class cast exception).  This would use memory more efficiently when most values are far
smaller than full precision, as is often the case (think java.math.BigDecimal, which operates
this way).  Moreover, there would be no need to have a whole bunch of separate (generated)
classes for different decimal precisions.  Just one class, variable width, handling any precision.
 I also suggest that some other "special cases" could be combined.  Fixed width is a special
case of variable width, where there's no need to store a separate length for each value. 
Non-nullable is a special case of nullable, where there's no need to store a nullable boolean
(or equivalent) for each value.  One last bit of feedback - it would be much easier to maintain
the code if it did not involve generation of code (freemarker).  An old-fashioned class hierarchy,
with no generated code, would probably work just fine for the vectoring mechanisms.


> Drill does not support Parquet DECIMAL values in variable length BINARY fields
> ------------------------------------------------------------------------------
>
>                 Key: DRILL-4184
>                 URL: https://issues.apache.org/jira/browse/DRILL-4184
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Storage - Parquet
>    Affects Versions: 1.4.0
>         Environment: Windows 7 Professional, Java 1.8.0_66
>            Reporter: Dave Oshinsky
>
> Encoding a DECIMAL logical type in Parquet using the variable length BINARY primitive
type is not supported by Drill as of versions 1.3.0 and 1.4.0.  The problem first surfaces
with the ClassCastException shown below, but fixing the immediate cause of the exception is
not sufficient to support this combination (DECIMAL, BINARY) in a Parquet file.
> In Drill, DECIMAL is currently assumed to be INT32, INT64, INT96, or FIXED_LEN_BINARY_ARRAY.
 Are there any plans to support DECIMAL with variable length BINARY?  Avro definitely supports
encoding DECIMAL in variable length bytes (see https://avro.apache.org/docs/current/spec.html#Decimal),
but this support in Parquet is less clear.
> Selecting on a BINARY DECIMAL field in a parquet file throws an exception as shown below
(java.lang.ClassCastException: org.apache.drill.exec.vector.Decimal28SparseVector cannot be
cast to org.apache.drill.exec.vector.VariableWidthVector).  The successful query at bottom
selected on a string field in the same file.
> 0: jdbc:drill:zk=local> select count(*) from dfs.`c:/dao/DBArchivePredictor/tenrows.parquet`
where acct_no=70000020;
> org.apache.drill.common.exceptions.DrillRuntimeException: Error in parquet recor
> d reader.
> Message: Failure in setting up reader
> Parquet Metadata: ParquetMetaData{FileMetaData{schema: message sbi.acct_mstr {
>   required binary ACCT_NO (DECIMAL(20,0));
>   optional binary SF_NO (UTF8);
>   optional binary LF_NO (UTF8);
>   optional binary BRANCH_NO (DECIMAL(20,0));
>   optional binary INTRO_CUST_NO (DECIMAL(20,0));
>   optional binary INTRO_ACCT_NO (DECIMAL(20,0));
>   optional binary INTRO_SIGN (UTF8);
>   optional binary TYPE (UTF8);
>   optional binary OPR_MODE (UTF8);
>   optional binary CUR_ACCT_TYPE (UTF8);
>   optional binary TITLE (UTF8);
>   optional binary CORP_CUST_NO (DECIMAL(20,0));
>   optional binary APLNDT (UTF8);
>   optional binary OPNDT (UTF8);
>   optional binary VERI_EMP_NO (DECIMAL(20,0));
>   optional binary VERI_SIGN (UTF8);
>   optional binary MANAGER_SIGN (UTF8);
>   optional binary CURBAL (DECIMAL(8,2));
>   optional binary STATUS (UTF8);
> }
> , metadata: {parquet.avro.schema={"type":"record","name":"acct_mstr","namespace"
> :"sbi","fields":[{"name":"ACCT_NO","type":{"type":"bytes","logicalType":"decimal
> ","precision":20,"scale":0,"cv_auto_incr":false,"cv_case_sensitive":false,"cv_co
> lumn_class":"java.math.BigDecimal","cv_connection":"oracle.jdbc.driver.T4CConnec
> tion","cv_currency":true,"cv_def_writable":false,"cv_nullable":0,"cv_precision":
> 20,"cv_read_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":true,"cv_s
> ubscript":1,"cv_type":2,"cv_typename":"NUMBER","cv_writable":true}},{"name":"SF_
> NO","type":["null",{"type":"string","cv_auto_incr":false,"cv_case_sensitive":tru
> e,"cv_column_class":"java.lang.String","cv_currency":false,"cv_def_writable":fal
> se,"cv_nullable":1,"cv_precision":10,"cv_read_only":false,"cv_scale":0,"cv_searc
> hable":true,"cv_signed":true,"cv_subscript":2,"cv_type":12,"cv_typename":"VARCHA
> R2","cv_writable":true}]},{"name":"LF_NO","type":["null",{"type":"string","cv_au
> to_incr":false,"cv_case_sensitive":true,"cv_column_class":"java.lang.String","cv
> _currency":false,"cv_def_writable":false,"cv_nullable":1,"cv_precision":10,"cv_r
> ead_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":true,"cv_subscript
> ":3,"cv_type":12,"cv_typename":"VARCHAR2","cv_writable":true}]},{"name":"BRANCH_
> NO","type":["null",{"type":"bytes","logicalType":"decimal","precision":20,"scale
> ":0,"cv_auto_incr":false,"cv_case_sensitive":false,"cv_column_class":"java.math.
> BigDecimal","cv_currency":true,"cv_def_writable":false,"cv_nullable":1,"cv_preci
> sion":20,"cv_read_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":true
> ,"cv_subscript":4,"cv_type":2,"cv_typename":"NUMBER","cv_writable":true}]},{"nam
> e":"INTRO_CUST_NO","type":["null",{"type":"bytes","logicalType":"decimal","preci
> sion":20,"scale":0,"cv_auto_incr":false,"cv_case_sensitive":false,"cv_column_cla
> ss":"java.math.BigDecimal","cv_currency":true,"cv_def_writable":false,"cv_nullab
> le":1,"cv_precision":20,"cv_read_only":false,"cv_scale":0,"cv_searchable":true,"
> cv_signed":true,"cv_subscript":5,"cv_type":2,"cv_typename":"NUMBER","cv_writable
> ":true}]},{"name":"INTRO_ACCT_NO","type":["null",{"type":"bytes","logicalType":"
> decimal","precision":20,"scale":0,"cv_auto_incr":false,"cv_case_sensitive":false
> ,"cv_column_class":"java.math.BigDecimal","cv_currency":true,"cv_def_writable":f
> alse,"cv_nullable":1,"cv_precision":20,"cv_read_only":false,"cv_scale":0,"cv_sea
> rchable":true,"cv_signed":true,"cv_subscript":6,"cv_type":2,"cv_typename":"NUMBE
> R","cv_writable":true}]},{"name":"INTRO_SIGN","type":["null",{"type":"string","c
> v_auto_incr":false,"cv_case_sensitive":true,"cv_column_class":"java.lang.String"
> ,"cv_currency":false,"cv_def_writable":false,"cv_nullable":1,"cv_precision":1,"c
> v_read_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":true,"cv_subscr
> ipt":7,"cv_type":12,"cv_typename":"VARCHAR2","cv_writable":true}]},{"name":"TYPE
> ","type":["null",{"type":"string","cv_auto_incr":false,"cv_case_sensitive":true,
> "cv_column_class":"java.lang.String","cv_currency":false,"cv_def_writable":false
> ,"cv_nullable":1,"cv_precision":2,"cv_read_only":false,"cv_scale":0,"cv_searchab
> le":true,"cv_signed":true,"cv_subscript":8,"cv_type":12,"cv_typename":"VARCHAR2"
> ,"cv_writable":true}]},{"name":"OPR_MODE","type":["null",{"type":"string","cv_au
> to_incr":false,"cv_case_sensitive":true,"cv_column_class":"java.lang.String","cv
> _currency":false,"cv_def_writable":false,"cv_nullable":1,"cv_precision":2,"cv_re
> ad_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":true,"cv_subscript"
> :9,"cv_type":12,"cv_typename":"VARCHAR2","cv_writable":true}]},{"name":"CUR_ACCT
> _TYPE","type":["null",{"type":"string","cv_auto_incr":false,"cv_case_sensitive":
> true,"cv_column_class":"java.lang.String","cv_currency":false,"cv_def_writable":
> false,"cv_nullable":1,"cv_precision":4,"cv_read_only":false,"cv_scale":0,"cv_sea
> rchable":true,"cv_signed":true,"cv_subscript":10,"cv_type":12,"cv_typename":"VAR
> CHAR2","cv_writable":true}]},{"name":"TITLE","type":["null",{"type":"string","cv
> _auto_incr":false,"cv_case_sensitive":true,"cv_column_class":"java.lang.String",
> "cv_currency":false,"cv_def_writable":false,"cv_nullable":1,"cv_precision":30,"c
> v_read_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":true,"cv_subscr
> ipt":11,"cv_type":12,"cv_typename":"VARCHAR2","cv_writable":true}]},{"name":"COR
> P_CUST_NO","type":["null",{"type":"bytes","logicalType":"decimal","precision":20
> ,"scale":0,"cv_auto_incr":false,"cv_case_sensitive":false,"cv_column_class":"jav
> a.math.BigDecimal","cv_currency":true,"cv_def_writable":false,"cv_nullable":1,"c
> v_precision":20,"cv_read_only":false,"cv_scale":0,"cv_searchable":true,"cv_signe
> d":true,"cv_subscript":12,"cv_type":2,"cv_typename":"NUMBER","cv_writable":true}
> ]},{"name":"APLNDT","type":["null",{"type":"string","cv_auto_incr":false,"cv_cas
> e_sensitive":false,"cv_column_class":"java.sql.Timestamp","cv_currency":false,"c
> v_def_writable":false,"cv_nullable":1,"cv_precision":0,"cv_read_only":false,"cv_
> scale":0,"cv_searchable":true,"cv_signed":true,"cv_subscript":13,"cv_type":93,"c
> v_typename":"DATE","cv_writable":true}]},{"name":"OPNDT","type":["null",{"type":
> "string","cv_auto_incr":false,"cv_case_sensitive":false,"cv_column_class":"java.
> sql.Timestamp","cv_currency":false,"cv_def_writable":false,"cv_nullable":1,"cv_p
> recision":0,"cv_read_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":t
> rue,"cv_subscript":14,"cv_type":93,"cv_typename":"DATE","cv_writable":true}]},{"
> name":"VERI_EMP_NO","type":["null",{"type":"bytes","logicalType":"decimal","prec
> ision":20,"scale":0,"cv_auto_incr":false,"cv_case_sensitive":false,"cv_column_cl
> ass":"java.math.BigDecimal","cv_currency":true,"cv_def_writable":false,"cv_nulla
> ble":1,"cv_precision":20,"cv_read_only":false,"cv_scale":0,"cv_searchable":true,
> "cv_signed":true,"cv_subscript":15,"cv_type":2,"cv_typename":"NUMBER","cv_writab
> le":true}]},{"name":"VERI_SIGN","type":["null",{"type":"string","cv_auto_incr":f
> alse,"cv_case_sensitive":true,"cv_column_class":"java.lang.String","cv_currency"
> :false,"cv_def_writable":false,"cv_nullable":1,"cv_precision":1,"cv_read_only":f
> alse,"cv_scale":0,"cv_searchable":true,"cv_signed":true,"cv_subscript":16,"cv_ty
> pe":12,"cv_typename":"VARCHAR2","cv_writable":true}]},{"name":"MANAGER_SIGN","ty
> pe":["null",{"type":"string","cv_auto_incr":false,"cv_case_sensitive":true,"cv_c
> olumn_class":"java.lang.String","cv_currency":false,"cv_def_writable":false,"cv_
> nullable":1,"cv_precision":1,"cv_read_only":false,"cv_scale":0,"cv_searchable":t
> rue,"cv_signed":true,"cv_subscript":17,"cv_type":12,"cv_typename":"VARCHAR2","cv
> _writable":true}]},{"name":"CURBAL","type":["null",{"type":"bytes","logicalType"
> :"decimal","precision":8,"scale":2,"cv_auto_incr":false,"cv_case_sensitive":fals
> e,"cv_column_class":"java.math.BigDecimal","cv_currency":true,"cv_def_writable":
> false,"cv_nullable":1,"cv_precision":8,"cv_read_only":false,"cv_scale":2,"cv_sea
> rchable":true,"cv_signed":true,"cv_subscript":18,"cv_type":2,"cv_typename":"NUMB
> ER","cv_writable":true}]},{"name":"STATUS","type":["null",{"type":"string","cv_a
> uto_incr":false,"cv_case_sensitive":true,"cv_column_class":"java.lang.String","c
> v_currency":false,"cv_def_writable":false,"cv_nullable":1,"cv_precision":1,"cv_r
> ead_only":false,"cv_scale":0,"cv_searchable":true,"cv_signed":true,"cv_subscript
> ":19,"cv_type":12,"cv_typename":"VARCHAR2","cv_writable":true}]}]}}}, blocks: [B
> lockMetaData{10, 1281 [ColumnMetaData{SNAPPY [ACCT_NO] BINARY  [BIT_PACKED, PLAI
> N], 4}, ColumnMetaData{SNAPPY [SF_NO] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY
> ], 88}, ColumnMetaData{SNAPPY [LF_NO] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY
> ], 163}, ColumnMetaData{SNAPPY [BRANCH_NO] BINARY  [RLE, BIT_PACKED, PLAIN_DICTI
> ONARY], 241}, ColumnMetaData{SNAPPY [INTRO_CUST_NO] BINARY  [RLE, BIT_PACKED, PL
> AIN_DICTIONARY], 298}, ColumnMetaData{SNAPPY [INTRO_ACCT_NO] BINARY  [RLE, BIT_P
> ACKED, PLAIN_DICTIONARY], 364}, ColumnMetaData{SNAPPY [INTRO_SIGN] BINARY  [RLE,
>  BIT_PACKED, PLAIN_DICTIONARY], 421}, ColumnMetaData{SNAPPY [TYPE] BINARY  [RLE,
>  BIT_PACKED, PLAIN_DICTIONARY], 478}, ColumnMetaData{SNAPPY [OPR_MODE] BINARY  [
> RLE, BIT_PACKED, PLAIN_DICTIONARY], 538}, ColumnMetaData{SNAPPY [CUR_ACCT_TYPE]
> BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 598}, ColumnMetaData{SNAPPY [TITLE]
>  BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 658}, ColumnMetaData{SNAPPY [CORP_
> CUST_NO] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 736}, ColumnMetaData{SNAPP
> Y [APLNDT] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 802}, ColumnMetaData{SNA
> PPY [OPNDT] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 919}, ColumnMetaData{SN
> APPY [VERI_EMP_NO] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 1036}, ColumnMet
> aData{SNAPPY [VERI_SIGN] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 1093}, Col
> umnMetaData{SNAPPY [MANAGER_SIGN] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY], 1
> 150}, ColumnMetaData{SNAPPY [CURBAL] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONARY]
> , 1207}, ColumnMetaData{SNAPPY [STATUS] BINARY  [RLE, BIT_PACKED, PLAIN_DICTIONA
> RY], 1270}]}]}
>         at org.apache.drill.exec.store.parquet.columnreaders.ParquetRecordReader
> .handleAndRaise(ParquetRecordReader.java:346)
>         at org.apache.drill.exec.store.parquet.columnreaders.ParquetRecordReader
> .setup(ParquetRecordReader.java:339)
>         at org.apache.drill.exec.physical.impl.ScanBatch.<init>(ScanBatch.java:1
> 01)
>         at org.apache.drill.exec.store.parquet.ParquetScanBatchCreator.getBatch(
> ParquetScanBatchCreator.java:168)
>         at org.apache.drill.exec.store.parquet.ParquetScanBatchCreator.getBatch(
> ParquetScanBatchCreator.java:56)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch(ImplCr
> eator.java:151)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getChildren(ImplCreat
> or.java:174)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch(ImplCr
> eator.java:131)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getChildren(ImplCreat
> or.java:174)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch(ImplCr
> eator.java:131)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getChildren(ImplCreat
> or.java:174)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch(ImplCr
> eator.java:131)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getChildren(ImplCreat
> or.java:174)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch(ImplCr
> eator.java:131)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getChildren(ImplCreat
> or.java:174)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getRecordBatch(ImplCr
> eator.java:131)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getChildren(ImplCreat
> or.java:174)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getRootExec(ImplCreat
> or.java:105)
>         at org.apache.drill.exec.physical.impl.ImplCreator.getExec(ImplCreator.j
> ava:79)
>         at org.apache.drill.exec.work.fragment.FragmentExecutor.run(FragmentExec
> utor.java:230)
>         at org.apache.drill.common.SelfCleaningRunnable.run(SelfCleaningRunnable
> .java:38)
>         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.
> java:1142)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
> .java:617)
>         at java.lang.Thread.run(Thread.java:745)
> Caused by: java.lang.ClassCastException: org.apache.drill.exec.vector.Decimal28SparseVector
cannot be cast to org.apache.drill.exec.vector.VariableWidthVector
>         at org.apache.drill.exec.store.parquet.columnreaders.VarLengthValuesColu
> mn.<init>(VarLengthValuesColumn.java:44)
>         at org.apache.drill.exec.store.parquet.columnreaders.VarLengthColumnRead
> ers$Decimal28Column.<init>(VarLengthColumnReaders.java:52)
>         at org.apache.drill.exec.store.parquet.columnreaders.ColumnReaderFactory
> .getReader(ColumnReaderFactory.java:178)
>         at org.apache.drill.exec.store.parquet.columnreaders.ParquetRecordReader
> .setup(ParquetRecordReader.java:319)
>         ... 22 more
> Error: SYSTEM ERROR: ClassCastException: org.apache.drill.exec.vector.Decimal28S
> parseVector cannot be cast to org.apache.drill.exec.vector.VariableWidthVector
> Fragment 0:0
> [Error Id: 22bfa8dd-1129-4300-9449-409e96d6c800 on DaveOshinsky-PC.gp.cv.commvau
> lt.com:31010] (state=,code=0)
> 0: jdbc:drill:zk=local> select count(*) from dfs.`c:/dao/DBArchivePredictor/tenr
> ows.parquet` where opr_mode='JO';
> +---------+
> | EXPR$0  |
> +---------+
> | 10      |
> +---------+
> 1 row selected (0.406 seconds)
> 0: jdbc:drill:zk=local>
> The immediate cause of this exception is that Drill, in org.apache.drill.exec.store.parquet.columnreaders.ParquetRecordReader,
assumes that all BINARY values are encoded in VariableWidthVectors.  For BINARY DECIMAL, this
is not true, as for example Decimal28SparseVector is a FixedWidthVector, not a VariableWidthVector.
  The assumption that DECIMAL is not encoded in variable length BINARY is found in a number
of other places in the Drill code, including:
> org.apache.drill.exec.store.parquet.columnreaders.ColumnReaderFactory only contains logic
to handle DECIMAL with INT32, INT64, INT96, or FIXED_LEN_BYTE_ARRAY.  BINARY is not supported
with DECIMAL.
> org.apache.drill.exec.store.parquet.columnreaders.NullableFixedByteAlignedReaders does
not support a nullable reader for BINARY in getNullableColumnReader method.



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