I read this code from "Hadoop the Definitive Guide":
SELECT a.ad_id, a.campaign_id, a.account_id, b.user_id
FROM dim_ads a JOIN impression_logs b ON (b.ad_id = a.ad_id)
WHERE b.dateid = '2008-12-01') x
INSERT OVERWRITE DIRECTORY 'results_gby_adid'
SELECT x.ad_id, count(1), count(DISTINCT x.user_id) GROUP BY x.ad_id
INSERT OVERWRITE DIRECTORY 'results_gby_campaignid'
SELECT x.campaign_id, count(1), count(DISTINCT x.user_id) GROUP BY x.campaign_id
INSERT OVERWRITE DIRECTORY 'results_gby_accountid'
SELECT x.account_id, count(1), count(DISTINCT x.user_id) GROUP BY x.account_id;
but as my test, using several DISTINCT cannot get right results.
my hiveql as below:
CREATE TABLE IF NOT EXISTS a (logindate int, id int);
then
load local file to this table...
CREATE TABLE IF NOT EXISTS user (id INT) PARTITIONED BY (logindate INT) ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t' STORED AS TEXTFILE;
then
if inserting table separately:
INSERT OVERWRITE TABLE user PARTITION(logindate=20130120) SELECT DISTINCT(id) FROM a WHERE logindate=20130120;
INSERT OVERWRITE TABLE user PARTITION(logindate=20130121) SELECT DISTINCT(id) FROM a WHERE logindate=20130121;
the results are correct;
but if choosing the next multiple insert hql:
FROM a
INSERT OVERWRITE TABLE user PARTITION(logindate=20130120) SELECT DISTINCT(id) WHERE logindate=20130120
INSERT OVERWRITE TABLE user PARTITION(logindate=20130121) SELECT DISTINCT(id) WHERE logindate=20130121;
the results are not correct, both partitions have the same number of records, seems like select from DISTINCT(id) WHERE logindate=20130120 OR logindate=20130121
so is it a bug or did I write some wrong syntax?
DISTINCT has a bit of an odd history in the code as an alias to group by.
If there is a bug, then the version of hive you are using would be important to know since bugs are addressed in each release.
This might work:
FROM a
INSERT OVERWRITE TABLE user PARTITION(logindate=20130120) SELECT id WHERE logindate=20130120 GROUP BY id
INSERT OVERWRITE TABLE user PARTITION(logindate=20130121) SELECT id WHERE logindate=20130121 GROUP BY id;
if that doesn't work, this will definitely work...even though it isn't the approach you were attempting to use...
FROM (select distinct id, logindate from a where logindate in ('20130120','20130121')) subq_a
INSERT OVERWRITE TABLE user PARTITION(logindate=20130120) SELECT id WHERE logindate=20130120
INSERT OVERWRITE TABLE user PARTITION(logindate=20130120) SELECT id WHERE logindate=20130121;
Related
I'm new in Hive. I have three tables like this:
table1:
id;value
1;val1
2;val2
3;val3
table2
num;desc;refVal
1;desc;0
2;descd;0
3;desc;0
I want to create a new table3 that contains:
num;desc;refVal
1;desc;3
2;descd;3
3;desc;3
Where num and desc are columns from table2 and refVal is the max value of column id in table1
Can someone guide me to solve this?
First, you have to create an table to hold this.
CREATE TABLE my_new_table;
After that, you have to insert into this table, as showed here
INSERT INTO TABLE my_new_table
[PARTITION (partcol1=val1, partcol2=val2 ...)]
select_statement1;
In the select_statement1 you can use the same select you would normally use to join and select the columns you need.
For more informations, you can check here
I am using Toad for oracle 12c. I need to copy a table and data (40M) from one shcema to another (prod to test). However there is an unique key(not the PK for this table) called record_Id col which has something data like this 3.000*******19E15. About 2M rows has same numbers(I believe its because very large number) which are unique in prod. When I try to copy it violets the unique key of that col. I am using toad "export data to another schema" function to copy the data.
when I execute query in prod
select count(*) from table_name
OR
select count(distinct(record_id) from table_name
Both query gives the exact same numbers of data.
I don't have DBA permission. How do I copy all data without violating unique key of the table.
Thanks in advance!
You can use UPSERT for decisional INSERT or UPDATE or you may write small procedure for this.
you may consider to use NOT EXISTS, but your data is big and it might not be resource efficient.
insert into prod_tab
select * from other_tab t1 where NOT exists (
select 1 from prod_tab t2 where t1.id = t2.id
);
In Oracle you can use a MERGE query for that.
The following query proceeds as follows for each data row :
if the source record_id does not yet exist in the target table, a new record is inserted
else, the existing record is updated with source values
For the sake of the example, I assumed that there are two other columns in the table : column1 and column2.
MERGE INTO target_table t1
USING (SELECT * from source_table t2)
ON (t1.record_id = t2.record_id)
WHEN MATCHED THEN UPDATE SET
t1.column1 = t2.column1,
t1.column2 = t2.column2
WHEN NOT MATCHED THEN INSERT
(record_id, column1, column2) VALUES (t2.record_id, t2.column1, t2.column2)
I have identified some duplicates in my table:
-- DUPLICATES: ----
select PPLP_NAME,
START_TIME,
END_TIME,
count(*)
from PPLP_LOAD_GENSTAT
group by PPLP_NAME,
START_TIME,
END_TIME
having count(*) > 1
-- DUPLICATES: ----
How is it possible to delete them?
Even if you don't have the primary key, each record has a unique rowid associated.
By using the query below you delete only the records that don't have the maximum row id by self joining a table with the columns that cause duplication. This will make sure that you delete any duplicates.
DELETE FROM PPLP_LOAD_GENSTAT plg_outer
WHERE ROWID NOT IN(
select MAX(ROWID)
from PPLP_LOAD_GENSTAT plg_inner
WHERE plg_outer.pplp_name = plg_inner.pplg_name
AND plg_outer.start_time= plg_inner.start_time
AND plg_outer.end_time = plg_inner.end_time
);
I'd suggest something easier:
CREATE table NewTable as
SELECT DISTINCT pplp_name,start_time,end_time
FROM YourTable
Then delete your table, and rename the new table.
If you really want to delete records, you can find a few examples of how here.
I have an ORC Table. I populate it using the data from some other table as follows:
INSERT INTO TABLE orc_table_name SELECT * FROM other_table_name
Is there any way I can prevent inserting of duplicate entries into the ORC Table?
you can use not in command See a general code below: it inserts records to the orc_table_name based on the fact that value1 from TABLE_1 was not inserted before.
INSERT INTO orc_table_name
(Value1, Value2)
SELECT t1.Value1,
t1.Value2
FROM TABLE_1 t1
WHERE t1.Value1 NOT IN (SELECT Value1 FROM orc_table_name)
INSERT INTO orc_table_name(field1,field2....fieldn)
select field1,field2... field(n-1),MIN(fieldn) as fieldn
from other_table_name
Group By field1,field2...field(n-1)
I have a question regarding a unified insert query against tables with different data
structures (Oracle). Let me elaborate with an example:
tb_customers (
id NUMBER(3), name VARCHAR2(40), archive_id NUMBER(3)
)
tb_suppliers (
id NUMBER(3), name VARCHAR2(40), contact VARCHAR2(40), xxx, xxx,
archive_id NUMBER(3)
)
The only column that is present in all tables is [archive_id]. The plan is to create a new archive of the dataset by copying (duplicating) all records to a different database partition and incrementing the archive_id for those records accordingly. [archive_id] is always part of the primary key.
My problem is with select statements to do the actual duplication of the data. Because the columns are variable, I am struggling to come up with a unified select statement that will copy the data and update the archive_id.
One solution (that works), is to iterate over all the tables in a stored procedure and do a:
CREATE TABLE temp as (SELECT * from ORIGINAL_TABLE);
UPDATE temp SET archive_id=something;
INSERT INTO ORIGINAL_TABLE (select * from temp);
DROP TABLE temp;
I do not like this solution very much as the DDL commands muck up all restore points.
Does anyone else have any solution?
How about creating a global temporary table for each base table?
create global temporary table tb_customers$ as select * from tb_customers;
create global temporary table tb_suppliers$ as select * from tb_suppliers;
You don't need to create and drop these each time, just leave them as-is.
You're archive process is then a single transaction...
insert into tb_customers$ as select * from tb_customers;
update tb_customers$ set archive_id = :v_new_archive_id;
insert into tb_customers select * from tb_customers$;
insert into tb_suppliers$ as select * from tb_suppliers;
update tb_suppliers$ set archive_id = :v_new_archive_id;
insert into tb_suppliers select * from tb_suppliers$;
commit; -- this will clear the global temporary tables
Hope this helps.
I would suggest not having a single sql statement for all tables and just use and insert.
insert into tb_customers_2
select id, name, 'new_archive_id' from tb_customers;
insert into tb_suppliers_2
select id, name, contact, xxx, xxx, 'new_archive_id' from tb_suppliers;
Or if you really need a single sql statement for all of them at least precreate all the temp tables (as temp tables) and leave them in place for next time. Then just use dynamic sql to refer to the temp table.
insert into ORIGINAL_TABLE_TEMP (SELECT * from ORIGINAL_TABLE);
UPDATE ORIGINAL_TABLE_TEMP SET archive_id=something;
INSERT INTO NEW_TABLE (select * from ORIGINAL_TABLE_TEMP);