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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4704) select statement behavior is inconsistent for decimal values in parquet
Date Tue, 12 Jul 2016 16:01:20 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15373132#comment-15373132
] 

ASF GitHub Bot commented on DRILL-4704:
---------------------------------------

Github user daveoshinsky commented on a diff in the pull request:

    https://github.com/apache/drill/pull/517#discussion_r70468695
  
    --- Diff: exec/java-exec/src/main/codegen/templates/Decimal/CastIntDecimal.java ---
    @@ -64,7 +64,15 @@ public void setup() {
     
         public void eval() {
             out.scale = (int) scale.value;
    -        out.precision = (int) precision.value;
    --- End diff --
    
    The DRILL-4704 bug root cause was that there is no supplied precision in this case (casting
an int to a decimal), i.e., the "supplied precision" was a bogus value of 0, and the casted
decimal with precision 0 matched nothing (unless perhaps the value was 0, but I didn't try
that).  The most direct way I could fix this was to compute the precision, which just involves
a few integer divides by 10 basically.  It might be possible to assume a large enough precision
(say 38, to fit most any integer), but that would waste lots of space (to hold a much smaller
value than worst case precision of 38 can hold).  Moreover, whenever one assumes a "worst
case", eventually it's likely to hit a "worse than worst case" (remember fixed length char
buffers in C?  128, no 256, no 1024, and so on).  It's been a while since I ran this (and
it was difficult to debug because of the runtime code generation and compilation), but it
may be the case that the cast from int to decimal is done only once (to prepare a decimal
for comparison, just once), in which case the divisions by 10 really wouldn't make any difference.

    
        On Tuesday, July 12, 2016 11:13 AM, Aman Sinha <notifications@github.com> wrote:
     
    
     In exec/java-exec/src/main/codegen/templates/Decimal/CastIntDecimal.java:> @@ -64,7
+64,15 @@ public void setup() {
    >  
    >      public void eval() {
    >          out.scale = (int) scale.value;
    > -        out.precision = (int) precision.value;
    I am not too familiar with the decimal type but taking a closer look at the fix I don't
think we should ignore the supplied precision. Your fix will compute the precision in all
cases, which would be a performance overhead. It should be computing only when supplied precision
is 0. Thoughts ? —
    You are receiving this because you authored the thread.
    Reply to this email directly, view it on GitHub, or mute the thread.  
    
      


> select statement behavior is inconsistent for decimal values in parquet
> -----------------------------------------------------------------------
>
>                 Key: DRILL-4704
>                 URL: https://issues.apache.org/jira/browse/DRILL-4704
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Functions - Drill
>    Affects Versions: 1.6.0
>         Environment: Windows 7 Pro, Java 1.8.0_91
>            Reporter: Dave Oshinsky
>             Fix For: Future
>
>
> A select statement that searches a parquet file for a decimal value matching a specific
value behaves inconsistently.  The query expressed most simply finds nothing:
> 0: jdbc:drill:zk=local> select * from dfs.`c:/archiveHR/HR.EMPLOYEES` where employee_id
= 100;
> +--------------+-------------+------------+--------+---------------+-----------+
> | EMPLOYEE_ID  | FIRST_NAME  | LAST_NAME  | EMAIL  | PHONE_NUMBER  | HIRE_DATE |
> +--------------+-------------+------------+--------+---------------+-----------+
> +--------------+-------------+------------+--------+---------------+-----------+
> No rows selected (0.348 seconds)
> The query can be modified to find the matching row in a few ways, such as the following
(using between instead of '=', changing 100 to 100.0, or casting as decimal:
> 0: jdbc:drill:zk=local> select * from dfs.`c:/archiveHR/HR.EMPLOYEES` where employee_id
between 100 and 100;
> +--------------+-------------+------------+--------+---------------+-----------+
> | EMPLOYEE_ID  | FIRST_NAME  | LAST_NAME  | EMAIL  | PHONE_NUMBER  |       HIR |
> +--------------+-------------+------------+--------+---------------+-----------+
> | 100          | Steven      | King       | SKING  | 515.123.4567  | 2003-06-1 |
> +--------------+-------------+------------+--------+---------------+-----------+
> 1 row selected (0.226 seconds)
> 0: jdbc:drill:zk=local> select * from dfs.`c:/archiveHR/HR.EMPLOYEES` where employee_id
= 100.0;
> +--------------+-------------+------------+--------+---------------+-----------+
> | EMPLOYEE_ID  | FIRST_NAME  | LAST_NAME  | EMAIL  | PHONE_NUMBER  |       HIR |
> +--------------+-------------+------------+--------+---------------+-----------+
> | 100          | Steven      | King       | SKING  | 515.123.4567  | 2003-06-1 |
> +--------------+-------------+------------+--------+---------------+-----------+
> 1 row selected (0.259 seconds)
> 0: jdbc:drill:zk=local> select * from dfs.`c:/archiveHR/HR.EMPLOYEES` where cast(employee_id
AS DECIMAL) = 100;
> +--------------+-------------+------------+--------+---------------+-----------+
> | EMPLOYEE_ID  | FIRST_NAME  | LAST_NAME  | EMAIL  | PHONE_NUMBER  |       HIR |
> +--------------+-------------+------------+--------+---------------+-----------+
> | 100          | Steven      | King       | SKING  | 515.123.4567  | 2003-06-1 |
> +--------------+-------------+------------+--------+---------------+-----------+
> 1 row selected (0.232 seconds)
> 0: jdbc:drill:zk=local>
> The schema of the parquet data that is being searched is as follows:
> $ java -jar parquet-tools*1.jar meta c:/archiveHR/HR.EMPLOYEES/1.parquet
> file:           file:/c:/archiveHR/HR.EMPLOYEES/1.parquet
> creator:        parquet-mr version 1.8.1 (build 4aba4dae7bb0d4edbcf7923ae1339f28fd3f7fcf)
> .....
> file schema:    HR.EMPLOYEES
> --------------------------------------------------------------------------------
> EMPLOYEE_ID:    REQUIRED FIXED_LEN_BYTE_ARRAY O:DECIMAL R:0 D:0
> FIRST_NAME:     OPTIONAL BINARY O:UTF8 R:0 D:1
> LAST_NAME:      REQUIRED BINARY O:UTF8 R:0 D:0
> EMAIL:          REQUIRED BINARY O:UTF8 R:0 D:0
> PHONE_NUMBER:   OPTIONAL BINARY O:UTF8 R:0 D:1
> HIRE_DATE:      REQUIRED BINARY O:UTF8 R:0 D:0
> JOB_ID:         REQUIRED BINARY O:UTF8 R:0 D:0
> SALARY:         OPTIONAL FIXED_LEN_BYTE_ARRAY O:DECIMAL R:0 D:1
> COMMISSION_PCT: OPTIONAL FIXED_LEN_BYTE_ARRAY O:DECIMAL R:0 D:1
> MANAGER_ID:     OPTIONAL FIXED_LEN_BYTE_ARRAY O:DECIMAL R:0 D:1
> DEPARTMENT_ID:  OPTIONAL FIXED_LEN_BYTE_ARRAY O:DECIMAL R:0 D:1
> row group 1:    RC:107 TS:9943 OFFSET:4
> --------------------------------------------------------------------------------
> EMPLOYEE_ID:     FIXED_LEN_BYTE_ARRAY SNAPPY DO:0 FPO:4 SZ:360/355/0.99 VC:107 ENC:PLAIN,BIT_PACKED
> FIRST_NAME:      BINARY SNAPPY DO:0 FPO:364 SZ:902/1058/1.17 VC:107 ENC:PLAIN_DICTIONARY,RLE,BIT_PACKED
> LAST_NAME:       BINARY SNAPPY DO:0 FPO:1266 SZ:913/1111/1.22 VC:107 ENC:PLAIN,BIT_PACKED
> EMAIL:           BINARY SNAPPY DO:0 FPO:2179 SZ:977/1184/1.21 VC:107 ENC:PLAIN,BIT_PACKED
> PHONE_NUMBER:    BINARY SNAPPY DO:0 FPO:3156 SZ:750/1987/2.65 VC:107 ENC:PLAIN,RLE,BIT_PACKED
> HIRE_DATE:       BINARY SNAPPY DO:0 FPO:3906 SZ:874/2636/3.02 VC:107 ENC:PLAIN_DICTIONARY,BIT_PACKED
> JOB_ID:          BINARY SNAPPY DO:0 FPO:4780 SZ:254/302/1.19 VC:107 ENC:PLAIN_DICTIONARY,BIT_PACKED
> SALARY:          FIXED_LEN_BYTE_ARRAY SNAPPY DO:0 FPO:5034 SZ:419/580/1.38 VC:107 ENC:PLAIN,RLE,BIT_PACKED
> COMMISSION_PCT:  FIXED_LEN_BYTE_ARRAY SNAPPY DO:0 FPO:5453 SZ:97/113/1.16 VC:107 ENC:PLAIN,RLE,BIT_PACKED
> MANAGER_ID:      FIXED_LEN_BYTE_ARRAY SNAPPY DO:0 FPO:5550 SZ:168/363/2.16 VC:107 ENC:PLAIN,RLE,BIT_PACKED
> DEPARTMENT_ID:   FIXED_LEN_BYTE_ARRAY SNAPPY DO:0 FPO:5718 SZ:94/254/2.70 VC:107 ENC:PLAIN,RLE,BIT_PACKED



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