presto

问题 If I ssh onto the master node of my presto emr cluster, I can run queries. However, I would like to be able to run queries from java source code on my local machine that connects to the emr cluster. I set up my presto emr cluster with default configurations. I have tried port forwarding, but it still does not seem to work. When I create the connection, I print it out and it is "com.facebook.presto.jdbc.PrestoConnection@XXXXXXX" but I still have doubts if it is actually connected since I can't

问题 We use Spark to flatten out clickstream data and then write the same to S3 in ORC+zlib format, I have tried changing many settings in Spark but still the resultant stripe sizes of the ORC file getting created are very small (<2MB) Things which I tried so far to decrease the stripe size, Earlier each file was 20MB in size, using coalesce I am now creating files which are of 250-300MB in size, but still there are 200 stripes per file i.e each stripe <2MB Tried using hivecontext instead of

问题 I'm storing daily reports per client for query with Athena. At first I thought I'd use a client=c_1/month=12/day=01/ or client=c2/date=2020-12-01/ folder structure, and run MSCK REPAIR TABLE daily to make new day partition available for query. Then I realized there's the $path special column, so if I store files as 2020-12-01.csv I could run a query with WHERE $path LIKE '%12-01% thus saving a partition and the need to detect/add it daily. I can see this having an impact on performance if

问题 Im trying to create a output of boolen values on back of some conditions. OutPut: EX: I have 3 rules/conditions from different tables which are not related to each other. Rule 1: Select USER_NAME, ID from session_user where age > 25 Rule 2: Select USER_NAME, ID from current_user where plan = 'gold' Rule 3: Select USER_NAME, ID from customer where group_name='managers' My OutPut Should be: USER_NAME | ID | Rule 1 | Rule 2 | Rule 3 user1 1 true false true user2 2 false true true user3 3 true

问题 Im trying to create a output of boolen values on back of some conditions. OutPut: EX: I have 3 rules/conditions from different tables which are not related to each other. Rule 1: Select USER_NAME, ID from session_user where age > 25 Rule 2: Select USER_NAME, ID from current_user where plan = 'gold' Rule 3: Select USER_NAME, ID from customer where group_name='managers' My OutPut Should be: USER_NAME | ID | Rule 1 | Rule 2 | Rule 3 user1 1 true false true user2 2 false true true user3 3 true

问题 I have a sql (Presto) table that contains data about different kinds of bird species. The table contains information about how often the different species have been observed in a park over different months. Some of the species have not been observed in certain months, but measurements were only performed on 07-9-19 , 08-10-19 , and 05-11-19 . A sample of the data would look like this Species Period Total (Cumulative) Observations (TCO) Bird1 07-9-19 33 Bird1 08-10-19 45 Bird1 05-11-19 60

问题 I am writing a custom Presto Aggregation Function that produces the correct result if (and only if) the values are ordered in ascending order by the value that I am aggregating on. i.e. The following will work: SELECT key, MY_AGG_FUNC(value ORDER BY value ASC) FROM my_table GROUP BY key The following will yield an incorrect result: SELECT key, MY_AGG_FUNC(value) FROM my_table GROUP BY key When developing the MY_AGG_FUNC , is there a way to enforce ORDER BY value ASC internally without relying

问题 I have a table that has 3 columns- start, end and emp_num. I want to generate a new table which has all dates between these dates for every employee. Need to use Presto. I refered this link - inserting dates into a table between a start and end date in Presto Tried using unnest function by creating sequence but , I don't know how do I create sequence by pulling dates from two columns in another table. select unnest(seq) as t(days) from (select sequence(start, end, interval '1' day) as seq

问题 I have a table that has 3 columns- start, end and emp_num. I want to generate a new table which has all dates between these dates for every employee. Need to use Presto. I refered this link - inserting dates into a table between a start and end date in Presto Tried using unnest function by creating sequence but , I don't know how do I create sequence by pulling dates from two columns in another table. select unnest(seq) as t(days) from (select sequence(start, end, interval '1' day) as seq

问题 I want all the possible combination of a number in a given set of array. I tried using some of the predefined functions of presto like array_agg(x) Input : [1,2,3,4] Output when n=2 : [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]] when n=3 : [[1,2,3],[1,2,4],[1,3,4],[2,3,4]] when n=4 : [[1,2,3,4]] or [1,2,3,4] 回答1: There is combinations(array(T), n) function and it does exactly what you want: select combinations(array[1,2,3,4],2); 来源： https://stackoverflow.com/questions/56540393/presto-sql-how-can-i