amazon-redshift

问题 I have daily sales data as below. I am trying to group by sales week wise. I tried using group by that gives total count for the period, how could I modify the query to obtain an output as shown below: Expected output: Last N days,Count,Category Last 7 days,225,Category_1 Last 14 days,136,Category_2 Last 7 days,172,Category_1 Last 14 days,321,Category_2 Input data: Date,*Sales*,Category 01-06-2018,10,Category_1 01-06-2018,19,Category_1 03-06-2018,3,Category_1 04-06-2018,13,Category_1 05-06

问题 I have a table with around 30 billions rows in Redshift with following structure, userid itemid country start_date uid1 itemid1 country1 2018-07-25 00:00:00 uid2 itemid2 country1 2018-07-25 00:00:00 uid3 itemid1 country2 2018-07-25 00:00:00 uid4 itemid3 country1 2018-07-25 00:00:00 uid5 itemid1 country1 2018-07-25 00:00:00 uid1 itemid2 country2 2018-07-25 00:00:00 uid2 itemid2 country2 2018-07-25 00:00:00 Here, I want to find item's are bought by how many unique users and then pick top 1000

问题 I have a table in Redshift. I want to add a column which should have incremental values. I dont want to drop the table and create a new one. Please suggest the command to add a column having auto incremental values in redshift table. Thanks !!! 回答1: It is not possible to add an IDENTITY column to an existing table. It might be easiest to create a new table with the new IDENTITY column, and copy the data into it. Note that the values aren't guaranteed to increase monotonically - i.e. there may

问题 So in postgresql I can do something like: SELECT has_table_privilege('myuser', 'mytable', 'select') to see whether myuser has select access on mytable . Is there something similar for user groups? Basically, I'd like to be able to submit a query to see if a group has certain privileges on a specified table. Thanks! 回答1: You could make a simple function to query role privileges; CREATE FUNCTION role_has_table_privilege(g NAME, tn NAME, pt NAME) RETURNS boolean AS 'SELECT EXISTS (SELECT 1 FROM

问题 How can we create all the combinations of any length for the values in one column and return the distinct count of another column for that combination? Table: +------+--------+ | Type | Name | +------+--------+ | A | Tom | | A | Ben | | B | Ben | | B | Justin | | C | Ben | +------+--------+ Output Table: +-------------+-------+ | Combination | Count | +-------------+-------+ | A | 2 | | B | 2 | | C | 1 | | AB | 3 | | BC | 2 | | AC | 2 | | ABC | 3 | +-------------+-------+ When the combination

问题 I am trying to generate time series in Redshift and insert into table, but no luck. What I have tried so far: insert into date(dateid,date) SELECT to_char(datum, 'YYYYMMDD')::int AS dateid, datum::date AS date FROM ( select '1970-01-01'::date + generate_series(0, 20000) as datum ) tbl; Getting the following error SQL Error [500310] [0A000]: [Amazon](500310) Invalid operation: Specified types or functions (one per INFO message) not supported on Redshift tables.; Any ideas or workaround ? 回答1:

问题 I've a status table and I want to fetch the latest details. Slno | ID | Status | date 1 | 1 | Pass | 15-06-2015 11:11:00 - this is inserted first 2 | 1 | Fail | 15-06-2015 11:11:00 - this is inserted second 3 | 2 | Fail | 15-06-2015 12:11:11 - this is inserted first 4 | 2 | Pass | 15-06-2015 12:11:11 - this is inserted second I use a window function with partition by ID order by date desc to fetch the first value. Excepted Output : 2 | 1 | Fail | 15-06-2015 11:11:00 - this is inserted second

问题 I have a table with a column updated_at , which is a sort key. After running both VACUUM and ANALYZE on the table, this is the query plan I get when filtering on updated_at : EXPLAIN SELECT * FROM my_table WHERE updated_at > '2018-01-01'; QUERY PLAN XN Seq Scan on my_table (cost=0.00..0.00 rows=1 width=723) Filter: (updated_at > '2018-01-01 00:00:00'::timestamp without time zone) My understanding is that the query execution engine is doing a sequential scan of the table despite the sort key

问题 I want to set tcp keep alive on my linux machine. So what I am doing is running a script if [ `/sbin/sysctl -n net.ipv4.tcp_keepalive_time` != 200 ] ; then /sbin/sysctl -w net.ipv4.tcp_keepalive_time=200; But I still have issues with connections to amazon's redshift. Can someone please help and show me how I can check if tcp keep alive is actually set or not? 回答1: To check if keep alive is active open a connection, don't exchange any data and verify with tcpdump or similar that packets gets

问题 I have a dataframe in R with various different data types. While writing the dataframe from R to redshift server, I am getting error only with character and timestamp values. I am adding R code snippet below to give you more idea about the issue. library(lubridate) library(dplyr) dat <- data.frame(id = letters[1:2], x = 2:3, date = now()) dat str(dat) drv <- dbDriver("PostgreSQL") conn <- dbConnect(drv, host="redshift.amazonaws.com", port="5439", dbname="abcd", user="xyz", password="abc") DBI