Related
I've tried to find an answer on several forums with no luck, so perhaps you can help me out.
I've got an INSERT ALL request that inserts thousands of rows at once.
INSERT ALL
INTO my_table (field_x, field_y, field_z) VALUES ('value_x1', 'value_y1', 'value_z1')
INTO my_table (field_x, field_y, field_z) VALUES ('value_x2', 'value_y2', 'value_z2')
...
INTO my_table (field_x, field_y, field_z) VALUES ('value_xn', 'value_yn', 'value_zn')
SELECT * FROM DUAL;
Now I'd like to amend it to update rows when some criteria are met. For each row, I could have something like:
MERGE INTO my_table m
USING (SELECT 'value_xi' x, 'value_yi' y, 'value_zi' z FROM DUAL) s
ON (m.field_x = s.x and m.field_y = s.y)
WHEN MATCHED THEN UPDATE SET
field_z = s.z,
WHEN NOT MATCHED THE INSERT (field_x, field_y, field_z)
VALUE(s.x, s.y, s.z);
Is there a way for me to do a kind of "MERGE ALL" that would allow to have all those merge requests in one?
Or maybe I'm missing the point and there's a better way to do this?
Thanks,
Edit: One possible solution is to use "UNION ALL" for a set of selects from dual, as follows:
MERGE INTO my_table m
USING (
select '' as x, '' as y, '' as z from dual
union all select 'value_x1', 'value_y1', 'value_z1' from dual
union all select 'value_x2', 'value_y2', 'value_z2' from dual
[...]
union all select 'value_xn', 'value_yn', 'value_zn' from dual
) s
ON (m.field_x = s.x and m.field_y = s.y)
WHEN MATCHED THEN UPDATE SET
field_z = s.z,
WHEN NOT MATCHED THEN INSERT (field_x, field_y, field_z)
VALUES (s.x, s.y, s.z);
NB: I've used a first empty row to be able generate all rows in the same format when I write the request. I also specify the columns names there.
Another solution would be to create a temporary table, INSERT ALL data into it, then merge with the target table and delete the temporary table.
If you're passing in tens of thousands of rows from your python script, I would do:
Create a global temporary table (GTT - this is a permanent table that holds data at session level)
Get your python script to insert the rows into the GTT
Use the GTT in the Merge statement, e.g.:
merge into your_main_table tgt
using your_gtt src
on (<join conditions>)
when matched then
update ...
when not matched then
insert ...;
I have a table with >1M rows of data and 20+ columns.
Within my table (tableX) I have identified duplicate records (~80k) in one particular column (troubleColumn).
If possible I would like to retain the original table name and remove the duplicate records from my problematic column otherwise I could create a new table (tableXfinal) with the same schema but without the duplicates.
I am not proficient in SQL or any other programming language so please excuse my ignorance.
delete from Accidents.CleanedFilledCombined
where Fixed_Accident_Index
in(select Fixed_Accident_Index from Accidents.CleanedFilledCombined
group by Fixed_Accident_Index
having count(Fixed_Accident_Index) >1);
You can remove duplicates by running a query that rewrites your table (you can use the same table as the destination, or you can create a new table, verify that it has what you want, and then copy it over the old table).
A query that should work is here:
SELECT *
FROM (
SELECT
*,
ROW_NUMBER()
OVER (PARTITION BY Fixed_Accident_Index)
row_number
FROM Accidents.CleanedFilledCombined
)
WHERE row_number = 1
UPDATE 2019: To de-duplicate rows on a single partition with a MERGE, see:
https://stackoverflow.com/a/57900778/132438
An alternative to Jordan's answer - this one scales better when having too many duplicates:
#standardSQL
SELECT event.* FROM (
SELECT ARRAY_AGG(
t ORDER BY t.created_at DESC LIMIT 1
)[OFFSET(0)] event
FROM `githubarchive.month.201706` t
# GROUP BY the id you are de-duplicating by
GROUP BY actor.id
)
Or a shorter version (takes any row, instead of the newest one):
SELECT k.*
FROM (
SELECT ARRAY_AGG(x LIMIT 1)[OFFSET(0)] k
FROM `fh-bigquery.reddit_comments.2017_01` x
GROUP BY id
)
To de-duplicate rows on an existing table:
CREATE OR REPLACE TABLE `deleting.deduplicating_table`
AS
# SELECT id FROM UNNEST([1,1,1,2,2]) id
SELECT k.*
FROM (
SELECT ARRAY_AGG(row LIMIT 1)[OFFSET(0)] k
FROM `deleting.deduplicating_table` row
GROUP BY id
)
Not sure why nobody mentioned DISTINCT query.
Here is the way to clean duplicate rows:
CREATE OR REPLACE TABLE project.dataset.table
AS
SELECT DISTINCT * FROM project.dataset.table
If your schema doesn’t have any records - below variation of Jordan’s answer will work well enough with writing over same table or new one, etc.
SELECT <list of original fields>
FROM (
SELECT *, ROW_NUMBER() OVER (PARTITION BY Fixed_Accident_Index) AS pos,
FROM Accidents.CleanedFilledCombined
)
WHERE pos = 1
In more generic case - with complex schema with records/netsed fields, etc. - above approach can be a challenge.
I would propose to try using Tabledata: insertAll API with rows[].insertId set to respective Fixed_Accident_Index for each row.
In this case duplicate rows will be eliminated by BigQuery
Of course, this will involve some client side coding - so might be not relevant for this particular question.
I havent tried this approach by myself either but feel it might be interesting to try :o)
If you have a large-size partitioned table, and only have duplicates in a certain partition range. You don't want to overscan nor process the whole table. use the MERGE SQL below with predicates on partition range:
-- WARNING: back up the table before this operation
-- FOR large size timestamp partitioned table
-- -------------------------------------------
-- -- To de-duplicate rows of a given range of a partition table, using surrage_key as unique id
-- -------------------------------------------
DECLARE dt_start DEFAULT TIMESTAMP("2019-09-17T00:00:00", "America/Los_Angeles") ;
DECLARE dt_end DEFAULT TIMESTAMP("2019-09-22T00:00:00", "America/Los_Angeles");
MERGE INTO `gcp_project`.`data_set`.`the_table` AS INTERNAL_DEST
USING (
SELECT k.*
FROM (
SELECT ARRAY_AGG(original_data LIMIT 1)[OFFSET(0)] k
FROM `gcp_project`.`data_set`.`the_table` AS original_data
WHERE stamp BETWEEN dt_start AND dt_end
GROUP BY surrogate_key
)
) AS INTERNAL_SOURCE
ON FALSE
WHEN NOT MATCHED BY SOURCE
AND INTERNAL_DEST.stamp BETWEEN dt_start AND dt_end -- remove all data in partiion range
THEN DELETE
WHEN NOT MATCHED THEN INSERT ROW
credit: https://gist.github.com/hui-zheng/f7e972bcbe9cde0c6cb6318f7270b67a
Easier answer, without a subselect
SELECT
*,
ROW_NUMBER()
OVER (PARTITION BY Fixed_Accident_Index)
row_number
FROM Accidents.CleanedFilledCombined
WHERE TRUE
QUALIFY row_number = 1
The Where True is neccesary because qualify needs a where, group by or having clause
Felipe's answer is the best approach for most cases. Here is a more elegant way to accomplish the same:
CREATE OR REPLACE TABLE Accidents.CleanedFilledCombined
AS
SELECT
Fixed_Accident_Index,
ARRAY_AGG(x LIMIT 1)[SAFE_OFFSET(0)].* EXCEPT(Fixed_Accident_Index)
FROM Accidents.CleanedFilledCombined AS x
GROUP BY Fixed_Accident_Index;
To be safe, make sure you backup the original table before you run this ^^
I don't recommend to use ROW NUMBER() OVER() approach if possible since you may run into BigQuery memory limits and get unexpected errors.
Update BigQuery schema with new table column as bq_uuid making it NULLABLE and type STRING
Create duplicate rows by running same command 5 times for example
insert into beginner-290513.917834811114.messages (id, type, flow, updated_at) Values(19999,"hello", "inbound", '2021-06-08T12:09:03.693646')
Check if duplicate entries exist
select * from beginner-290513.917834811114.messages where id = 19999
Use generate uuid function to generate uuid corresponding to each message
UPDATE beginner-290513.917834811114.messages
SET bq_uuid = GENERATE_UUID()
where id>0
Clean duplicate entries
DELETE FROM beginner-290513.917834811114.messages
WHERE bq_uuid IN
(SELECT bq_uuid
FROM
(SELECT bq_uuid,
ROW_NUMBER() OVER( PARTITION BY updated_at
ORDER BY bq_uuid ) AS row_num
FROM beginner-290513.917834811114.messages ) t
WHERE t.row_num > 1 );
I think I could use some help here from more experienced users...
I have an integer field name in a table, let's call it SO_ID in a table SO, and to each new row I need to calculate a new SO_ID based on the following rules
1) SO_ID consists of 6 letters where first 3 are an area code, and the last three is the sequenced number within this area.
309001
309002
309003
2) so the next new row will have a SO_ID of value
309004
3) if someone deletes the row with SO_ID value = 309002, then the next new row must recycle this value, so the next new row has got to have the SO_ID of value
309002
can anyone please provide me with either a SQL function or PL/SQL (perhaps a trigger straightaway?) function that would return the next available SO_ID I need to use ?
I reckon I could get use of keyword rownum in my sql, but the follwoing just doens't work properly
select max(so_id),max(rownum) from(
select (so_id),rownum,cast(substr(cast(so_id as varchar(6)),4,3) as int) from SO
where length(so_id)=6
and substr(cast(so_id as varchar(6)),1,3)='309'
and cast(substr(cast(so_id as varchar(6)),4,3) as int)=rownum
order by so_id
);
thank you for all your help!
This kind of logic is fraught with peril. What if two sessions calculate the same "next" value, or both try to reuse the same "deleted" value? Since your column is an integer, you'd probably be better off querying "between 309001 and 309999", but that begs the question of what happens when you hit the thousandth item in area 309?
Is it possible to make SO_ID a foreign key to another table as well as a unique key? You could pre-populate the parent table with all valid IDs (or use a function to generate them as needed), and then it would be a simple matter to select the lowest one where a child record doesn't exist.
well, we came up with this... sort of works.. concurrency is 'solved' via unique constraint
select min(lastnumber)
from
(
select so_id,so_id-LAG(so_id, 1, so_id) OVER (ORDER BY so_id) AS diff,LAG(so_id, 1, so_id) OVER (ORDER BY so_id)as lastnumber
from so_miso
where substr(cast(so_id as varchar(6)),1,3)='309'
and length(so_id)=6
order by so_id
)a
where diff>1;
Do you really need to compute & store this value at the time a row is inserted? You would normally be better off storing the area code and a date in a table and computing the SO_ID in a view, i.e.
SELECT area_code ||
LPAD( DENSE_RANK() OVER( PARTITION BY area_code
ORDER BY date_column ),
3,
'0' ) AS so_id,
<<other columns>>
FROM your_table
or having a process that runs periodically (nightly, for example) to assign the SO_ID using similar logic.
If your application is not pure sql, you could do this in application code (ie: Java code). This would be more straightforward.
If you are recycling numbers when rows are deleted, your base table must be consulted when generating the next number. "Legacy" pre-relational schemes that attempt to encode information in numbers are a pain to make airtight when numbers must be recycled after deletes, as you say yours must.
If you want to avoid having to scan your table looking for gaps, an after-delete routine must write the deleted number to a separate table in a "ReuseMe" column. The insert routine does this:
begins trans
selects next-number table for update
uses a reuseme number if available else uses the next number
clears the reuseme number if applicable or increments the next-number in the next-number table
commits trans
Ignoring the issues about concurrency, the following should give a decent start.
If 'traffic' on the table is low enough, go with locking the table in exclusive mode for the duration of the transaction.
create table blah (soc_id number(6));
insert into blah select 309000 + rownum from user_tables;
delete from blah where soc_id = 309003;
commit;
create or replace function get_next (i_soc in number) return number is
v_min number := i_soc* 1000;
v_max number := v_min + 999;
begin
lock table blah in exclusive mode;
select min(rn) into v_min
from
(select rownum rn from dual connect by level <= 999
minus
select to_number(substr(soc_id,4))
from blah
where soc_id between v_min and v_max);
return v_min;
end;
Here's my original question:
merging two data sets
Unfortunately I omitted some intircacies, that I'd like to elaborate here.
So I have two tables events_source_1 and events_source_2 tables. I have to produce the data set from those tables into resultant dataset (that I'd be able to insert into third table, but that's irrelevant).
events_source_1 contain historic event data and I have to do get the most recent event (for such I'm doing the following:
select event_type,b,c,max(event_date),null next_event_date
from events_source_1
group by event_type,b,c,event_date,null
events_source_2 contain the future event data and I have to do the following:
select event_type,b,c,null event_date, next_event_date
from events_source_2
where b>sysdate;
How to put outer join statement to fill the void (i.e. when same event_type,b,c found from event_source_2 then next_event_date will be filled with the first date found
GREATLY APPRECIATE FOR YOUR HELP IN ADVANCE.
Hope I got your question right. This should return the latest event_date of events_source_1 per event_type, b, c and add the lowest event_date of event_source_2.
Select es1.event_type, es1.b, es1.c,
Max(es1.event_date),
Min(es2.event_date) As next_event_date
From events_source_1 es1
Left Join events_source_2 es2 On ( es2.event_type = es1.event_type
And es2.b = es1.b
And es2.c = es1.c
)
Group By c1.event_type, c1.b, c1.c
You could just make the table where you need to select a max using a group by into a virtual table, and then do the full outer join as I provided in the answer to the prior question.
Add something like this to the top of the query:
with past_source as (
select event_type, b, c, max(event_date)
from event_source_1
group by event_type, b, c, event_date
)
Then you can use past_source as if it were an actual table, and continue your select right after the closing parens on the with clause shown.
I end up doing two step process: 1st step populates the data from event table 1, 2nd step MERGES the data between target (the dataset from 1st step) and another source. Please forgive me, but I had to obfuscate table name and omit some columns in the code below for legal reasons. Here's the SQL:
INSERT INTO EVENTS_TARGET (VEHICLE_ID,EVENT_TYPE_ID,CLIENT_ID,EVENT_DATE,CREATED_DATE)
select VEHICLE_ID, EVENT_TYPE_ID, DEALER_ID,
max(EVENT_INITIATED_DATE) EVENT_DATE, sysdate CREATED_DATE
FROM events_source_1
GROUP BY VEHICLE_ID, EVENT_TYPE_ID, DEALER_ID, sysdate;
Here's the second step:
MERGE INTO EVENTS_TARGET tgt
USING (
SELECT ee.VEHICLE_ID VEHICLE_ID, ee.POTENTIAL_EVENT_TYPE_ID POTENTIAL_EVENT_TYPE_ID, ee.CLIENT_ID CLIENT_ID,ee.POTENTIAL_EVENT_DATE POTENTIAL_EVENT_DATE FROM EVENTS_SOURCE_2 ee WHERE ee.POTENTIAL_EVENT_DATE>SYSDATE) src
ON (tgt.vehicle_id = src.VEHICLE_ID AND tgt.client_id=src.client_id AND tgt.EVENT_TYPE_ID=src.POTENTIAL_EVENT_TYPE_ID)
WHEN MATCHED THEN
UPDATE SET tgt.NEXT_EVENT_DATE=src.POTENTIAL_EVENT_DATE
WHEN NOT MATCHED THEN
insert (tgt.VEHICLE_ID,tgt.EVENT_TYPE_ID,tgt.CLIENT_ID,tgt.NEXT_EVENT_DATE,tgt.CREATED_DATE) VALUES (src.VEHICLE_ID, src.POTENTIAL_EVENT_TYPE_ID, src.CLIENT_ID, src.POTENTIAL_EVENT_DATE, SYSDATE)
;
This question already has answers here:
SQL IN Clause 1000 item limit
(5 answers)
Closed 8 years ago.
Is there any way to get around the Oracle 10g limitation of 1000 items in a static IN clause? I have a comma delimited list of many of IDs that I want to use in an IN clause, Sometimes this list can exceed 1000 items, at which point Oracle throws an error. The query is similar to this...
select * from table1 where ID in (1,2,3,4,...,1001,1002,...)
Put the values in a temporary table and then do a select where id in (select id from temptable)
select column_X, ... from my_table
where ('magic', column_X ) in (
('magic', 1),
('magic', 2),
('magic', 3),
('magic', 4),
...
('magic', 99999)
) ...
I am almost sure you can split values across multiple INs using OR:
select * from table1 where ID in (1,2,3,4,...,1000) or
ID in (1001,1002,...,2000)
You may try to use the following form:
select * from table1 where ID in (1,2,3,4,...,1000)
union all
select * from table1 where ID in (1001,1002,...)
Where do you get the list of ids from in the first place? Since they are IDs in your database, did they come from some previous query?
When I have seen this in the past it has been because:-
a reference table is missing and the correct way would be to add the new table, put an attribute on that table and join to it
a list of ids is extracted from the database, and then used in a subsequent SQL statement (perhaps later or on another server or whatever). In this case, the answer is to never extract it from the database. Either store in a temporary table or just write one query.
I think there may be better ways to rework this code that just getting this SQL statement to work. If you provide more details you might get some ideas.
Use ...from table(... :
create or replace type numbertype
as object
(nr number(20,10) )
/
create or replace type number_table
as table of numbertype
/
create or replace procedure tableselect
( p_numbers in number_table
, p_ref_result out sys_refcursor)
is
begin
open p_ref_result for
select *
from employees , (select /*+ cardinality(tab 10) */ tab.nr from table(p_numbers) tab) tbnrs
where id = tbnrs.nr;
end;
/
This is one of the rare cases where you need a hint, else Oracle will not use the index on column id. One of the advantages of this approach is that Oracle doesn't need to hard parse the query again and again. Using a temporary table is most of the times slower.
edit 1 simplified the procedure (thanks to jimmyorr) + example
create or replace procedure tableselect
( p_numbers in number_table
, p_ref_result out sys_refcursor)
is
begin
open p_ref_result for
select /*+ cardinality(tab 10) */ emp.*
from employees emp
, table(p_numbers) tab
where tab.nr = id;
end;
/
Example:
set serveroutput on
create table employees ( id number(10),name varchar2(100));
insert into employees values (3,'Raymond');
insert into employees values (4,'Hans');
commit;
declare
l_number number_table := number_table();
l_sys_refcursor sys_refcursor;
l_employee employees%rowtype;
begin
l_number.extend;
l_number(1) := numbertype(3);
l_number.extend;
l_number(2) := numbertype(4);
tableselect(l_number, l_sys_refcursor);
loop
fetch l_sys_refcursor into l_employee;
exit when l_sys_refcursor%notfound;
dbms_output.put_line(l_employee.name);
end loop;
close l_sys_refcursor;
end;
/
This will output:
Raymond
Hans
I wound up here looking for a solution as well.
Depending on the high-end number of items you need to query against, and assuming your items are unique, you could split your query into batches queries of 1000 items, and combine the results on your end instead (pseudocode here):
//remove dupes
items = items.RemoveDuplicates();
//how to break the items into 1000 item batches
batches = new batch list;
batch = new batch;
for (int i = 0; i < items.Count; i++)
{
if (batch.Count == 1000)
{
batches.Add(batch);
batch.Clear()
}
batch.Add(items[i]);
if (i == items.Count - 1)
{
//add the final batch (it has < 1000 items).
batches.Add(batch);
}
}
// now go query the db for each batch
results = new results;
foreach(batch in batches)
{
results.Add(query(batch));
}
This may be a good trade-off in the scenario where you don't typically have over 1000 items - as having over 1000 items would be your "high end" edge-case scenario. For example, in the event that you have 1500 items, two queries of (1000, 500) wouldn't be so bad. This also assumes that each query isn't particularly expensive in of its own right.
This wouldn't be appropriate if your typical number of expected items got to be much larger - say, in the 100000 range - requiring 100 queries. If so, then you should probably look more seriously into using the global temporary tables solution provided above as the most "correct" solution. Furthermore, if your items are not unique, you would need to resolve duplicate results in your batches as well.
Yes, very weird situation for oracle.
if you specify 2000 ids inside the IN clause, it will fail.
this fails:
select ...
where id in (1,2,....2000)
but if you simply put the 2000 ids in another table (temp table for example), it will works
below query:
select ...
where id in (select userId
from temptable_with_2000_ids )
what you can do, actually could split the records into a lot of 1000 records and execute them group by group.
Here is some Perl code that tries to work around the limit by creating an inline view and then selecting from it. The statement text is compressed by using rows of twelve items each instead of selecting each item from DUAL individually, then uncompressed by unioning together all columns. UNION or UNION ALL in decompression should make no difference here as it all goes inside an IN which will impose uniqueness before joining against it anyway, but in the compression, UNION ALL is used to prevent a lot of unnecessary comparing. As the data I'm filtering on are all whole numbers, quoting is not an issue.
#
# generate the innards of an IN expression with more than a thousand items
#
use English '-no_match_vars';
sub big_IN_list{
#_ < 13 and return join ', ',#_;
my $padding_required = (12 - (#_ % 12)) % 12;
# get first dozen and make length of #_ an even multiple of 12
my ($a,$b,$c,$d,$e,$f,$g,$h,$i,$j,$k,$l) = splice #_,0,12, ( ('NULL') x $padding_required );
my #dozens;
local $LIST_SEPARATOR = ', '; # how to join elements within each dozen
while(#_){
push #dozens, "SELECT #{[ splice #_,0,12 ]} FROM DUAL"
};
$LIST_SEPARATOR = "\n union all\n "; # how to join #dozens
return <<"EXP";
WITH t AS (
select $a A, $b B, $c C, $d D, $e E, $f F, $g G, $h H, $i I, $j J, $k K, $l L FROM DUAL
union all
#dozens
)
select A from t union select B from t union select C from t union
select D from t union select E from t union select F from t union
select G from t union select H from t union select I from t union
select J from t union select K from t union select L from t
EXP
}
One would use that like so:
my $bases_list_expr = big_IN_list(list_your_bases());
$dbh->do(<<"UPDATE");
update bases_table set belong_to = 'us'
where id in ($bases_list_expr)
UPDATE
Instead of using IN clause, can you try using JOIN with the other table, which is fetching the id. that way we don't need to worry about limit. just a thought from my side.
Instead of SELECT * FROM table1 WHERE ID IN (1,2,3,4,...,1000);
Use this :
SELECT * FROM table1 WHERE ID IN (SELECT rownum AS ID FROM dual connect BY level <= 1000);
*Note that you need to be sure the ID does not refer any other foreign IDS if this is a dependency. To ensure only existing ids are available then :
SELECT * FROM table1 WHERE ID IN (SELECT distinct(ID) FROM tablewhereidsareavailable);
Cheers