Member since
01-27-2015
16
Posts
5
Kudos Received
4
Solutions
My Accepted Solutions
Title | Views | Posted |
---|---|---|
20129 | 05-11-2015 09:37 AM | |
2068 | 05-07-2015 08:34 AM | |
6989 | 04-28-2015 09:02 AM | |
7179 | 03-17-2015 11:39 AM |
07-20-2015
10:17 AM
1 Kudo
It should be fixed in CDH5.4.5
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05-11-2015
09:37 AM
COLUMNS_OLD is a deprecated table where columns used to be stored. Hive might have some information there for some reason. You can use both COLUMNS_OLD or COLUMNS_V2 when searching for your column.
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05-07-2015
08:34 AM
1 Kudo
I recommend the 2nd option where you have 3 columns only: (PK, DATE, MEASURE). You cannot update records on Hive, so having the 365 columns will leave 364 columns unused, and this causes extra storage on your files (like separators chars, schema information, etc). Also, for read performance, 3 columns is still better than 365. Hive reads the full record every time you do a query, it then selects the columns you want, and applies the filter from the WHERE statement. This select/filter will happen with 3 or 365 columns, so 3 will be faster. Also, you're queries would be shorter, as you only need to filter the query by date (instead of looking for columns that have measure data). And, if you use columnar storage files (like Parquet), this filter may be faster.
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