I have written below SQL in an RPGLE program. Intent is to update the header file (TC400F) if no corresponding records exist in detail file (TC401F). Are there better ways of doing this? By better, I mean that would make the query run faster or would make it look more cleaner.
Exec SQL UPDATE TC400F
SET T40STS = '05',
T40OFL = '1'
WHERE T40SID = :K#T41SID AND
T40PID = :K#T41PID AND
NOT EXISTS (SELECT * FROM TC401F WHERE
T41SID = :K#T41SID AND
T41PID = :K#T41PID );
try this :
Exec SQL UPDATE TC400F f1
SET (f1.T40STS, f1.T40OFL) = ('05', '1')
WHERE f1.T40SID = :K#T41SID AND
f1.T40PID = :K#T41PID AND
NOT EXISTS
(
SELECT * FROM TC401F f2
WHERE (f1.T41SID, f1.T41PID) = (f2.T41SID, f2.T41PID)
);
You have not done anything here that explicitly restricts performance. The optimizer is pretty smart these days. Most of the things that affect SQL performance are external to the statement. Best to write the statement to be semantically correct (as you have above), and let the optimizer do it's thing. Then if you see performance issues, then investigate them with then Explain tools in Run SQL Scripts. Most likely your performance issues will derive from incorrect indexes.
Exec SQL UPDATE TC400F
SET T40STS = '05',
T40OFL = '1'
WHERE (t40sts <> '05' or t40ofl <> '1')
and T40SID = :K#T41SID
AND T40PID = :K#T41PID
and
NOT EXISTS (SELECT onefieldhere FROM TC401F WHERE
T41SID = :K#T41SID AND
T41PID = :K#T41PID );
Add a little optimistic code don't update what is already set.
Please don't make the as400 an orphan by ending a line with an operator that is the start of the next line. Optimistic updates are probably fastest when values are already set because it knows its already done. You could make it better by using the alias field names so someone in the future will know what a t40ofl is. Select only one field from the exists clause so sql won't have to pull in a whole row.
Related
I have this merge query in oracle and it was working fine. Now we are migrating to postgres 10 and trying to find equivalent for this in postgres.
MERGE INTO s.act_pack C USING((SELECT A.jid, A.pid, B.pcode,
B.mc, A.md, A.hd FROM s.act_pack A INNER JOIN s.act_pack B
ON A.pid = B.pid AND A.pcode = B.mc AND (A.hd <> B.hd
OR A.md<> B.md)) order by A.upd_ts desc) D ON(C.pid = D.pid AND
C.pcode = D.pcode AND C.jid = D.jid) WHEN MATCHED THEN UPDATE SET C.md =
D.md, C.hd= D.hd;
I see some forums on web says postgres doesnt support merge, and use INSERT ... ON CONFLICT
but with no background in postgres, I am not able to understand how this complex query can be written using that.
And some says postgres9.5 and above support merge statement. since we are using postgres 10 tried to use same oracle query in postgres but recieved ERROR: syntax error at or near "MERGE"
Any help is highly appreciated.
You don't need an "UPSERT" as you are not doing an INSERT, so a regular UPDATE is enough:
update act_pack C
SET C.md = D.md,
C.hd = D.h
from (
SELECT A.jid, A.pid, B.pcode, B.mc, A.md, A.hd
FROM s.act_pack A
INNER JOIN s.act_pack B
ON A.pid = B.pid
AND A.pcode = B.mc
AND (A.hd <> B.hd OR A.md<> B.md)
) d
where C.pid = D.pid
AND C.pcode = D.pcode
AND C.jid = D.jid
This is a direct "translation" of your code. But the fact that the same table is used three times is a bit strange. But without more information it's hard to know where exactly this could be made more efficient.
I wrote T-SQL MERGE query to merge staging data into a data warehouse (you can find it at the bottom).
If I uncomment the OUTPUT statement the I get error mentioned in the title.
However, if I do not include it, everything works perfectly fine and MERGE succeeds.
I know that there are some issue connected to the MERGE clause, however there are more connected to the type of merge.
I checked the following answer: [https://dba.stackexchange.com/questions/140880/why-does-this-merge-statement-cause-the-session-to-be-killed], however in my execution plan I cannot find exactly index insert followed by index merge.
Rather, what I see is the following execution plan
Code was developed on database attached to SQL Server 2012 (SP4) instance
I would really appreciate good explanation of this problem, ideally referencing steps from my execution plan.
Thank you.
declare #changes table (chgType varchar(50),Id varchar(18))
begin try
set xact_abort on
begin tran
;with TargetUserLogHsh as (select
hsh =hashbytes('md5',concat(coalesce([AccountName],'')
,coalesce([TaxNumber],'')))
,LastLoginCast = coalesce(CONVERT(datetime,LastLogin,103),getdate())
,* from
dw.table1)
,SourceUserLogHsh as (select
hsh =hashbytes('md5',concat(coalesce([AccountName],'')
,coalesce([TaxNumber],'')))
,LastLoginCast = coalesce(CONVERT(datetime,LastLogin,103),getdate())
,* from
sta.table1)
merge TargetUserLogHsh target
using SourceUserLogHsh source
on target.ContactId = source.ContactId and target.Lastlogincast >= source.LastLoginCast
when not matched then insert (
[AccountName]
,[TaxNumber]
,[LastLogin]
)
values (
source.[AccountName]
,source.[TaxNumber]
,source.[LastLogin]
)
when matched and target.lastlogincast = source.lastlogincast
and target.hsh != source.hsh then
update
set
[AccountName] = source.[AccountName]
,[TaxNumber] = source.[TaxNumber]
,[LastLogin] = source.[LastLogin]
output $action,inserted.contactid into #changes
;
commit tran
end try
begin catch
if ##TRANCOUNT > 0 rollback tran
select ERROR_MESSAGE()
end catch
I have the following select statement in ABAP:
SELECT munic~mandt VREFER BIS AB ZZELECDATE ZZCERTDATE CONSYEAR ZDIMO ZZONE_M ZZONE_T USAGE_M USAGE_T M2MC M2MT M2RET EXEMPTMCMT EXEMPRET CHARGEMCMT
INTO corresponding fields of table GT_INSTMUNIC_F
FROM ZCI00_INSTMUNIC AS MUNIC
INNER JOIN EVER AS EV on
MUNIC~POD = EV~VREFER(9).
"where EV~BSTATUS = '14' or EV~BSTATUS = '32'.
My problem with the above statement is that does not recognize the substring/offset operation on the 'ON' clause. If i remove the '(9) then
it recognizes the field, otherwise it gives error:
Field ev~refer is unknown. It is neither in one of the specified tables
nor defined by a "DATA" statement. I have also tried doing something similar in the 'Where' clause, receiving a similar error:
LOOP AT gt_instmunic.
clear wa_gt_instmunic_f.
wa_gt_instmunic_f-mandt = gt_instmunic-mandt.
wa_gt_instmunic_f-bis = gt_instmunic-bis.
wa_gt_instmunic_f-ab = gt_instmunic-ab.
wa_gt_instmunic_f-zzelecdate = gt_instmunic-zzelecdate.
wa_gt_instmunic_f-ZZCERTDATE = gt_instmunic-ZZCERTDATE.
wa_gt_instmunic_f-CONSYEAR = gt_instmunic-CONSYEAR.
wa_gt_instmunic_f-ZDIMO = gt_instmunic-ZDIMO.
wa_gt_instmunic_f-ZZONE_M = gt_instmunic-ZZONE_M.
wa_gt_instmunic_f-ZZONE_T = gt_instmunic-ZZONE_T.
wa_gt_instmunic_f-USAGE_M = gt_instmunic-USAGE_M.
wa_gt_instmunic_f-USAGE_T = gt_instmunic-USAGE_T.
temp_pod = gt_instmunic-pod.
SELECT vrefer
FROM ever
INTO wa_gt_instmunic_f-vrefer
WHERE ( vrefer(9) LIKE temp_pod ). " PROBLEM WITH SUBSTRING
"AND ( BSTATUS = '14' OR BSTATUS = '32' ).
ENDSELECT.
WRITE: / sy-dbcnt.
WRITE: / 'wa is: ', wa_gt_instmunic_f.
WRITE: / 'wa-ever is: ', wa_gt_instmunic_f-vrefer.
APPEND wa_gt_instmunic_f TO gt_instmunic_f.
WRITE: / wa_gt_instmunic_f-vrefer.
ENDLOOP.
itab_size = lines( gt_instmunic_f ).
WRITE: / 'Internal table populated with', itab_size, ' lines'.
The basic task i want to implement is to modify a specific field on one table,
pulling values from another. They have a common field ( pod = vrefer(9) ). Thanks in advance for your time.
If you are on a late enough NetWeaver version, it works on 7.51, you can use the OpenSQL function LEFT or SUBSTRING. Your query would look something like:
SELECT munic~mandt VREFER BIS AB ZZELECDATE ZZCERTDATE CONSYEAR ZDIMO ZZONE_M ZZONE_T USAGE_M USAGE_T M2MC M2MT M2RET EXEMPTMCMT EXEMPRET CHARGEMCMT
FROM ZCI00_INSTMUNIC AS MUNIC
INNER JOIN ever AS ev
ON MUNIC~POD EQ LEFT( EV~VREFER, 9 )
INTO corresponding fields of table GT_INSTMUNIC_F.
Note that the INTO clause needs to move to the end of the command as well.
field(9) is a subset operation that is processed by the ABAP environment and can not be translated into a database-level SQL statement (at least not at the moment, but I'd be surprised if it ever will be). Your best bet is either to select the datasets separately and merge them manually (if both are approximately equally large) or pre-select one and use a FAE/IN clause.
They have a common field ( pod = vrefer(9) )
This is a wrong assumption, because they both are not fields, but a field an other thing.
If you really need to do that task through SQL, I'll suggest you to check native SQL sentences like SUBSTRING and check if you can manage to use them within an EXEC_SQL or (better) the CL_SQL* classes.
Background
Currently I am using DB2 V9 version. One of my stored procedure is taking time to execute. I looked BMC apptune and found the following SQL.
There are three tables we were using to execute the following query.
ACCOUNT table is having 3413 records
EXCHANGE_RATE is having 1267K records
BALANCE is having 113M records
Someone has added recently following piece of code in the query. I think because of this we had a problem.
AND (((A.ACT <> A.EW_ACT)
AND (A.EW_ACT <> ' ')
AND (C.ACT = A.EW_ACT))
OR (C.ACT = A.ACT))
Query
SELECT F1.CLO_LED
INTO :H :H
FROM (SELECT A.ACT, A.BNK, A.ACT_TYPE,
CASE WHEN :H = A.CUY_TYPE THEN DEC(C.CLO_LED, 21, 2)
ELSE DEC(MULTIPLY_ALT(C.CLO_LED, COALESCE(B.EXC_RATE, 0)), 21, 2)
END AS CLO_LED
FROM ACCOUNT A
LEFT OUTER JOIN EXCHANGE_RATE B
ON B.EFF_DATE = CURRENT DATE - 1 DAY
AND B.CURCY_FROM = A.CURNCY_TYPE
AND B.CURCY_TO = :H
AND B.STA_TYPE = 'A'
, BALANCE C
WHERE A.CUSR_ID = :DCL.CUST-ID
AND A.ACT = :DCL.ACT
AND A.EIG_RTN = :WS-BNK-ID
AND A.ACT_TYPE = :DCL.ACT-TYPE
AND A.ACT_CAT = :DCL.ACT-CAT
AND A.STA_TYPE = 'A'
AND (((A.ACT <> A.EW_ACT)
AND (A.EW_ACT <> ' ')
AND (C.ACT = A.EW_ACT))
OR (C.ACT = A.ACT))
AND C.BNK = :WS-BNK-ID
AND C.ACT_TYPE = :DCL.ACT-TYPE
AND C.BUS_DATE = :WS-DATE-FROM) F1
WITH UR
There's a number of wierd things going on in this query. The most twitchy of which is mixing explicit joins with the implicit-join syntax; frankly, I'm not certain how the system interprets it. You also appear to be using the same host-variable for both input and output; please don't.
Also, why are your column names so short? DB2 (that version, at least) supports column names that are much longer. Please save people's sanity, if at all possible.
We can't completely say why things are slow - we may need to see access plans. In the meantime, here's your query, restructured to what may be a faster form:
SELECT CASE WHEN :inputType = a.cuy_type THEN DEC(b.clo_led, 21, 2)
ELSE DEC(MULTIPLY_ALT(b.clo_led, COALESCE(c.exc_rate, 0)), 21, 2) END
INTO :amount :amountIndicator -- if you get results, do you need the indiciator?
FROM Account as a
JOIN Balance as b -- This is assumed to not be a 'left', given coalesce not used
ON b.bnk = a.eig_rtn
AND b.act_type = a.act_type
AND b.bus_date = :ws-date-from
AND ((a.act <> a.ew_act -- something feels wrong here, but
AND a.ew_act <> ' ' -- without knowing the data, I don't
AND c.act = a.ew_act) -- want to muck with it.
OR c.act = a.act)
LEFT JOIN Exchange_Rate as c
ON c.eff_date = current_date - 1 day
AND c.curcy_from = a.curncy_type
AND c.sta_type = a.sta_type
AND c.curcy_to = :destinationCurrency
WHERE a.cusr_id = :dcl.cust-id
AND a.act = :dcl.act
AND a.eig_rtn = :ws-bnk-id
AND a.act_type = :dcl.act-type
AND a.act_cat = :dcl.act-cat
AND a.sta_type = 'A'
WITH UR
FECTCH FIRST 1 ROW ONLY
A few other notes:
Only specify exactly those columns needed - under certain circumstances, this permits index-only access, where otherwise a followup table-access may be needed. However, this probably won't help here.
COALESCE(c.exc_rate, 0) feels off somehow - if no exchange rate is present, you return an amount of 0, which could otherwise be a valid amount. You may need to return some sort of indicator, or make it a normal join, not an outer one.
Also, try both this version, and possibly a version where host variables are specified in addition to the conditions between tables. The optimizer should be able to automatically commute the values, but may not under some conditions (implementation detail).
I'm trying to figure out a way to store metadata about a column without repeating myself.
I'm currently working on a generic dimension loading SSIS package that will handle all my dimensions. It currently does :
Create a temporary table identical to the given table name in parameters (this is a generic stored procedure that receive the table name as parameter, and then do : select top 0 * into ##[INSERT ORIGINAL TABLE NAME HERE] from [INSERT ORIGINAL TABLE NAME HERE]).
==> Here we insert custom code for this particular dimension that will first query the data from a datasource and get my delta, then transform the data and finally loads it into my temporary table.
Merge the temporary table into my original table with a T-SQL MERGE, taking care of type1 and type2 fields accordingly.
My problem right now is that I have to maintain a table with all the fields in it to store a metadata to tell my scripts if this particular field is type1 or type2... this is nonsense, I can get the same data (minus type1/type2) from sys.columns/sys.types.
I was ultimately thinking about renaming my fields to include their type in it, such as :
FirstName_T2, LastName_T2, Sex_T1 (well, I know this can be type2, let's not fall into that debate here).
What do you guyz would do with that? My solution (using a table with that metadata) is currently in place and working, but it's obvious that repeating myself from the systables to a custom table is nonsense, just for a simple type1/type2 info.
UPDATE: I also thought about creating user defined types like varchar => t1_varchar, t2_varchar, etc. This sounds like something a bit sluggy too...
Everything you need should already be in INFORMATION_SCHEMA.COLUMNS
I can't follow your thinking of not using provided tables/views...
Edit: As scarpacci mentioned, this somewhat portable if needed.
I know this is bad, but I will post an answer to my own question... Thanks to GBN for the help tho!
I am now storing "flags" in the "description" field of my columns. I, for example, can store a flag this way : "TYPE_2_DATA".
Then, I use this query to get the flag back for each and every column :
select columns.name as [column_name]
,types.name as [type_name]
,extended_properties.value as [column_flags]
from sys.columns
inner join sys.types
on columns.system_type_id = types.system_type_id
left join sys.extended_properties
on extended_properties.major_id = columns.object_id
and extended_properties.minor_id = columns.column_id
and extended_properties.name = 'MS_Description'
where object_id = ( select id from sys.sysobjects where name = 'DimDivision' )
and is_identity = 0
order by column_id
Now I can store metadata about columns without having to create a separate table. I use what's already in place and I don't repeat myself. I'm not sure this is the best possible solution yet, but it works and is far better than duplicating information.
In the future, I will be able to use this field to store more metadata, where as : "TYPE_2_DATA|ANOTHER_FLAG|ETC|OH BOY!".
UPDATE :
I now store the information in separate extended properties. You can manage extended properties using sp_addextendedproperty and sp_updateextendedproperty stored procedures. I have created a simple store procedure that help me to update those values regardless if they currently exist or not :
create procedure [dbo].[UpdateSCDType]
#tablename nvarchar(50),
#fieldname nvarchar(50),
#scdtype char(1),
#dbschema nvarchar(25) = 'dbo'
as
begin
declare #already_exists int;
if ( #scdtype = '1' or #scdtype = '2' )
begin
select #already_exists = count(1)
from sys.columns
inner join sys.extended_properties
on extended_properties.major_id = columns.object_id
and extended_properties.minor_id = columns.column_id
and extended_properties.name = 'ScdType'
where object_id = (select sysobjects.id from sys.sysobjects where sysobjects.name = #tablename)
and columns.name = #fieldname
if ( #already_exists = 0 )
begin
exec sys.sp_addextendedproperty
#name = N'Scd_Type',
#value = #scdtype,
#level0type = N'SCHEMA',
#level0name = #dbschema,
#level1type = N'TABLE',
#level1name = #tablename,
#level2type = N'COLUMN',
#level2name = #fieldname
end
else
begin
exec sys.sp_updateextendedproperty
#name = N'Scd_Type',
#value = #scdtype,
#level0type = N'SCHEMA',
#level0name = #dbschema,
#level1type = N'TABLE',
#level1name = #tablename,
#level2type = N'COLUMN',
#level2name = #fieldname
end
end
end
Thanks again