Good catch on empty string Veera! Wouldn't it be cheaper to check for an empty string? case when columns[] ='' then null else to_date(columns[],'yyyy-MM-dd') end
I don't think the option to read csv empty columns (or empty string in any text reader) as null is in the reader yet. So we can't check with columns[] is null. --Andries > On Oct 28, 2016, at 8:21 AM, Veera Naranammalpuram > <[email protected]> wrote: > > Do you have zero length strings in your data? I have seen cases where the > system option to cast empty strings to NULL doesn't work as advertised. You > should re-open DRILL-3214. > > When I run into this problem, I usually use a regex to workaround. The > PROJECT takes a performance hit when you do this for larger data sets but > it works. > > $cat nulls.psv > date_col|string_col > |test > 2016-10-28|test2 > $ sqlline > apache drill 1.8.0 > "a little sql for your nosql" > 0: jdbc:drill:> select date_col, string_col from `nulls.psv`; > +-------------+-------------+ > | date_col | string_col | > +-------------+-------------+ > | | test | > | 2016-10-28 | test2 | > +-------------+-------------+ > 2 rows selected (0.303 seconds) > 0: jdbc:drill:> select to_date(date_col,'yyyy-mm-dd') from `nulls.psv`; > Error: SYSTEM ERROR: IllegalArgumentException: Invalid format: "" > > Fragment 0:0 > > [Error Id: c058acbe-f2bf-4c3b-a447-66bebdc4c642 on se-node10.se.lab:31010] > (state=,code=0) > 0: jdbc:drill:> select case when date_col similar to '[0-9]+%' then > to_date(date_col,'yyyy-MM-dd') else null end as date_col_converted from > `nulls.psv`; > +---------------------+ > | date_col_converted | > +---------------------+ > | null | > | 2016-10-28 | > +---------------------+ > 2 rows selected (0.521 seconds) > 0: jdbc:drill:> alter system set > `drill.exec.functions.cast_empty_string_to_null` = true; > +-------+----------------------------------------------------------+ > | ok | summary | > +-------+----------------------------------------------------------+ > | true | drill.exec.functions.cast_empty_string_to_null updated. | > +-------+----------------------------------------------------------+ > 1 row selected (0.304 seconds) > 0: jdbc:drill:> select to_date(date_col,'yyyy-mm-dd') from `nulls.psv`; > Error: SYSTEM ERROR: IllegalArgumentException: Invalid format: "" > > Fragment 0:0 > > [Error Id: 92126a1b-1c03-4e90-bc3a-01c5c81bb013 on se-node10.se.lab:31010] > (state=,code=0) > 0: jdbc:drill:> > > -Veera > > On Fri, Oct 28, 2016 at 9:24 AM, Khurram Faraaz <[email protected]> > wrote: > >> All, >> >> Question is - why does it work for a parquet column and fails when CSV >> column is used ? >> >> Drill 1.9.0 commit : a29f1e29 >> >> This is a simple project of column from a csv file, works. >> {noformat} >> 0: jdbc:drill:schema=dfs.tmp> select columns[4] FROM `typeall_l.csv` t1 >> limit 5; >> +-------------+ >> | EXPR$0 | >> +-------------+ >> | 2011-11-04 | >> | 1986-10-22 | >> | 1992-09-10 | >> | 2016-08-07 | >> | 1986-01-25 | >> +-------------+ >> 5 rows selected (0.26 seconds) >> {noformat} >> >> Using TO_DATE function with columns[x] as first input fails, with an >> IllegalArgumentException >> {noformat} >> 0: jdbc:drill:schema=dfs.tmp> select to_date(columns[4],'yyyy-mm-dd') FROM >> `typeall_l.csv` t1 limit 5; >> Error: SYSTEM ERROR: IllegalArgumentException: Invalid format: "" >> >> Fragment 0:0 >> >> [Error Id: 9cff3eb9-4045-4d9a-a6a1-1eadaa597f30 on centos-01.qa.lab:31010] >> (state=,code=0) >> {noformat} >> >> However, interestingly same query over parquet column returns correct >> results, on same data. >> >> {noformat} >> 0: jdbc:drill:schema=dfs.tmp> select to_date(col_dt,'yyyy-mm-dd') FROM >> typeall_l limit 5; >> +-------------+ >> | EXPR$0 | >> +-------------+ >> | 2011-01-04 | >> | 1986-01-22 | >> | 1992-01-10 | >> | 2016-01-07 | >> | 1986-01-25 | >> +-------------+ >> 5 rows selected (0.286 seconds) >> {noformat} >> >> When the date string is passed as first input, to_date function returns >> correct results. >> {noformat} >> 0: jdbc:drill:schema=dfs.tmp> select to_date('2011-01-04','yyyy-mm-dd') >> from (values(1)); >> +-------------+ >> | EXPR$0 | >> +-------------+ >> | 2011-01-04 | >> +-------------+ >> 1 row selected (0.235 seconds) >> {noformat} >> >> Thanks, >> Khurram >> > > > > -- > Veera Naranammalpuram > Product Specialist - SQL on Hadoop > *MapR Technologies (www.mapr.com <http://www.mapr.com>)* > *(Email) [email protected] <[email protected]>* > *(Mobile) 917 683 8116 - can text * > *Timezone: ET (UTC -5:00 / -4:00)*
