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https://issues.apache.org/jira/browse/DRILL-4704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15411019#comment-15411019
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ASF GitHub Bot commented on DRILL-4704:
---------------------------------------
Github user paul-rogers commented on the issue:
https://github.com/apache/drill/pull/517
As a follow-up, the case we're focusing on is an implicit cast: one created
by the system to convert an integer to a decimal type in order to do an
equality check. To avoid the scale issue, the code that does the explcit cast
should check the type of integer and select a target decimal type that will
hold all values of that int type with a scale of 0. Does the code do that now?
It may be that the decimal type must also be cast so that the equality has the
same types. That is, if we compare Dec9 with Integer, we need a scale of 10 for
the Int, so we must cast the Int to Dec18. As a result, we must cast the Dec9
to Dec18.
The reason for all of this is that the casts are done statically. A more
efficient solution would be for the the run-time code to make a decision based
on actual values, but Drill is not set up that way. Another solution would be
to have an in-memory form of a decimal that caries the precision and scale so
we can set the scale per value. But, Drill is not set up that way either.
So, the change we've been discussing (setting scale based on int and
decimal types, ignoring overflow for now) seems the only short-term solution
for 1.8.
> 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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