We have some often-hit code in our app that increments a column, like so:
if (r = customer.find_or_generate_reminder)
r.counter += 1
r.save!
end
We're getting lock wait timeouts, so I'm thinking about making this an atomic operation. Naively, what I want to do looks like this:
if (r = customer.find_or_generate_reminder)
connection.excute('UPDATE customer_reminders SET counter=counter+1, updated_at=now() WHERE id = ' + r.id)
end
Is there a ruby-world way of doing the same thing?
You can use the class method increment_counter:
Customer.increment_counter :counter, customer
That'll create something like:
UPDATE `customers` SET `counter` = COALESCE(`counter`, 0) + 1 WHERE (`customers`.`id` = 53)
(you have to pass either an id or an instance of the class into this method (customer) unlike the customer.increment!(:counter) method which is not atomic)
I created a gem to make this more object oriented:
https://github.com/imme5150/rails_atomic_increment
Allows you to do:
customer.atomic_increment!( :counter )
Let me know what you think.
If you don't mind a little bit of SQL:
CustomerReminder.where(id: id).update_all('counter = counter + 1, updated_at = now()')
Related
I need to update two information on one object: the quantity (PLAF-gsmng) and refresh the planned order via the module function 'MD_SET_ACTION_PLAF'.
I successfully find a way to update each data separately. But when I execute the both solutions the second modification is not saved on the database.
Do you know how I can change the quantity & set the action on PLAF (Planned order) table ?
Do you know other module function to update only the quantity ?
Maybe a parameter missing ?
It's like if the second object is locked (sm12 empty, no sy-subrc = locked) ... and the modification is not committed.
I tried to:
change the order of the algorithm (refresh and after, change PLAF)
add, remove, move the COMMIT WORK & COMMIT WORK AND WAIT
add DEQUEUE_ALL or DEQUEUE_EMPLAFE
This is the current code:
1) Read the data
lv_plannedorder = '00000000001'
"Read PLAF data
SELECT SINGLE * FROM PLAF INTO ls_plaf WHERE plnum = lv_plannedorder.
2) Update Quantity data
" Standard configuration for FM MD_PLANNED_ORDER_CHANGE
CLEAR ls_610.
ls_610-nodia = 'X'. " No dialog display
ls_610-bapco = space. " BAPI type. Do not use mode 2 -> Action PLAF-MDACC will be autmatically set up to APCH by the FM
ls_610-bapix = 'X'. " Run BAPI
ls_610-unlox = 'X'. " Update PLAF
" Customize values
MOVE p_gsmng TO ls_plaf-gsmng. " Change quantity value
MOVE sy-datlo TO ls_plaf-mdacd. " Change by/datetime, because ls_610-bapco <> 2.
MOVE sy-uzeit TO ls_plaf-mdact.
CALL FUNCTION 'MD_PLANNED_ORDER_CHANGE'
EXPORTING
ecm61o = ls_610
eplaf = ls_plaf
EXCEPTIONS
locked = 1
locking_error = 2
OTHERS = 3.
" Already committed on the module function
" sy-subrc = 0
If I go on the PLAF table, I can see that the quantity is edited. It's working :)
3) Refresh BOM & change Action (MDACC) and others fields
CLEAR ls_imdcd.
ls_imdcd-pafxl = 'X'.
CALL FUNCTION 'MD_SET_ACTION_PLAF'
EXPORTING
iplnum = lv_plannedorder
iaccto = 'BOME'
iaenkz = 'X'
imdcd = ls_imdcd
EXCEPTIONS
illegal_interface = 1
system_failure = 2
error_message = 3
OTHERS = 4.
IF sy-subrc = 0.
COMMIT WORK.
ENDIF.
If I go on the table, no modification (only the modif. of the part 2. can be found on it).
Any idea ?
Maybe because the ls_610-bapco = space ?
It should be possible to update planned order quantity with MD_SET_ACTION_PLAF too, at least SAP Help tells us so. Why don't you use it like that?
Its call for changing the quantity should possibly look like this:
DATA: lt_acct LIKE TABLE OF MDACCTO,
ls_acct LIKE LINE OF lt_acct.
ls_acct-accto = 'BOME'.
APPEND lt_acct.
ls_acct-accto = 'CPOD'.
APPEND lt_acct.
is_mdcd-GSMNG = 'value' "updated quantity value
CALL FUNCTION 'MD_SET_ACTION_PLAF'
EXPORTING
iplnum = iv_plnum
iaenkz = 'X'
IVBKZ = 'X'
imdcd = is_mdcd "filled with your BOME-related data + new quantity
TABLES
TMDACCTO = lt_accto
EXCEPTIONS
illegal_interface = 1
system_failure = 2
error_message = 3.
So there is no more need for separate call of MD_PLANNED_ORDER_CHANGE anymore and no more problems with update.
I used word possibly because I didn't find any example of this FM call in the Web (and SAP docu is quite ambiguous), so I propose this solution just as is, without verification.
P.S. Possible actions are listed in T46AS table, and possible impact of imdcd fields on order can be checked in MDAC transaction. It is somewhat GUI equivalent of this FM for single order.
I have this snippet:
SELECT
CASE WHEN
AVG(UNIX_TIMESTAMP(tDone)-UNIX_TIMESTAMP(tIPN))/3600 >= 10
THEN
ROUND(AVG(UNIX_TIMESTAMP(tDone)-UNIX_TIMESTAMP(tIPN))/3600,0)
ELSE
ROUND(AVG(UNIX_TIMESTAMP(tDone)-UNIX_TIMESTAMP(tIPN))/3600,1)
END
FROM
...
Can I do anything to remove the duplication from this? Something along these lines, for instance: (Hypothetical code follows):
SET var = AVG(UNIX_TIMESTAMP(tDone)-UNIX_TIMESTAMP(tIPN))/3600
SELECT
CASE WHEN
var > 10
THEN
ROUND(var,0)
ELSE
ROUND(var,1)
END
FROM
...
With a subquery you can do something like this :
SELECT
CASE WHEN avgtiPN >= 10 THEN ROUND(avgtiPN,0) ELSE ROUND(avgtiPN,1) END
FROM
(SELECT
AVG(UNIX_TIMESTAMP(tDone)-UNIX_TIMESTAMP(tIPN))/3600 AS avgtiPN
FROM
...) AS AVGQuery
But I am still uncertain if it is more readable.
Yes, you can, but variable processing order is undefined for user-defined variables. This reference in the MySQL documentation explains when this works and when it doesnt.
I have a 3D array in Matlab of uint16(basically it is just an image 1080x1920x3). I want to store it in mysql. Here is what I'm doing:
MySQL:
create table imgtest(img longblob);
Matlab:
% image_data - is my image as described before
raw_im = reshape(image_data,1,[]);
conn = database('test','root','root','Vendor','MySQL','Server','localhost')
x = conn.Handle;
insertcommand = ['INSERT INTO imtest (img) values (?)'];
StatementObject = x.prepareStatement(insertcommand);
StatementObject.setObject(1,raw_im)
StatementObject.execute
The problem is that I'm writing about 600k uint16 values into this blob field. But when I take this field from the DB, I always getting about 1.2 million of uint8 elements(exactly two times more).
So, is there a way to read this byte field as a set of uint16, but not uint8?
Thank you.
I have been doing something similar for one of my projects
basically there was one difference but maybe it would clarify something to you.
I was loading image directly to DB from file with command:
INSERT INTO BaseImage(Image)
SELECT * FROM OPENROWSET(BULK N'C:\co.jpg', SINGLE_BLOB) as image
and getting it back to Matlab required typecasting (just like #sebastian mentioned)
SQL_query = 'select TOP 1 pk_BaseImage,Image from BaseImage order by pk_BaseImage desc';
[data] = SQL_query_exec(SQL_query);
pk_BaseImage = data.Data.pk_BaseImage;
out = typecast(data.Data.Image{1,1},'uint8');
BUT..
it was not enough, I had to do some trick to use 'out' as image
I was forced to write it to temporary file and read it again to Matlab (I know it's strange but it worked very well and I could for example calculate DWT, DFT and so on)
image_matrix = get_image_matrix( out );
get_image_matrix function looks like:
function [ out ] = get_image_matrix( input )
targetfilename = 'temp.jpg';
%wynik
fid = fopen(targetfilename,'w');
if fid
fwrite(fid,input,'uint8');
end
fclose(fid);
out = imread(targetfilename);
delete(targetfilename);
end
I hope it will help you :)
One important notice - I used gray-scale images (uint8 type)
You can most probably typecast the uint8's into uint16's to get back at your original image data:
uint16_result = typecast(uint8_result, 'uint16');
I'm not familiar with the database toolbox - so there might well be a way to tell Matlab to do this on its own.
OK, thank you both. I've summarized your answers and this what I've got:
Since blob field is nothing more than byte array, then we should cast our data in matlab before writing it to the DB. After reading it from DB, we should cast them back.
Minimum working example is:
MySQL
create table imgtest(img longblob);
Matlab
% image_data - is my image as described before
raw_im = typecast(reshape(image_data,1,[]),'uint8'); %! the main string
conn = database('test','root','root','Vendor','MySQL','Server','localhost')
x = conn.Handle;
insertcommand = ['INSERT INTO imtest (img) values (?)'];
StatementObject = x.prepareStatement(insertcommand);
StatementObject.setObject(1,raw_im)
StatementObject.execute
After we can read it back:
res = exec(conn,'Select * from imtest')
array_uint8 = fetch(res);
array_uint8 = array_uint8{1};
array_uint16 = typecast(array_uint8,'uint16').
Hope this will help someone.
I have some simple code that uses the minmax algoritm to locate birds. Everything works but I find my programming not good and I believe there is a better solution. I'm not that experienced in RoR but if somebody knows a better way to achieve the same solution then I'm greatful ;).
There are two parts I hate, the 4 lists I had to create to determine the max or min value for the different combinations (the core of the min-max algorithm) and the very ugly SQL hack.
Thanks!
def index
# fetch all our birds
#birds = Bird.all
# Loop over the birds
#birds.each do |bird|
#fixed = Node.where("d7type = 'f'")
xminmax = []
xmaxmin = []
yminmax = []
ymaxmin = []
#fixed.each do |fixed|
rss = Log.find_by_sql("SELECT logs.fixed_mac, AVG(logs.blinker_rss) AS avg_rss FROM logs
WHERE logs.blinker_mac = '#{bird.d7_mac}' AND logs.fixed_mac = '#{fixed.d7_mac}' ORDER BY logs.id DESC LIMIT 30")
converted_rss = calculate_distance_rss(rss[0].attributes["avg_rss"])
xminmax.push(fixed.xpos + converted_rss)
xmaxmin.push(fixed.xpos - converted_rss)
yminmax.push(fixed.ypos + converted_rss)
ymaxmin.push(fixed.ypos - converted_rss)
end
pos = {x: (xminmax.min + xmaxmin.max) / 2, y: (yminmax.min + ymaxmin.max) / 2}
puts pos
end
end
2 things you could do to start with is (assuming Birds could be a large table) Change Bird.all to
Bird.find_each do |bird|
... code ...
end
It's a more efficient way to loop over many table records.
2nd: take #fixed = Node.where("d7type = 'f'") out of the each loop since it doesn't need any variables for its query. Put it above the loop so it doesn't execute each time.
3rd (Not so much of an optimization but just safer code): Your Log.find_by_sql looks simple enough to use active_record, you can change it to:
Log.select('fixed_mac, AVG(logs.blinker_rss) AS avg_rss, blinker_mac').
where(blinker_mac: bird.d7_mac, fixed_mac: fixed.d7_mac).
order('id DESC').limit(30)
converted_rss = calculate_distance_rss(rss.first.avg_rss)
Everything else looks fine.
I'm new to sqlalchemy and could use some help.
I'm trying to write a small application for which i have to dynamically change a select-statement. So I do s = select([files]), and then i add filters by s = s.where(files.c.createtime.between(val1, val2)).
This works great, but only with an AND-conjunction.
So, when I want to have all entries with createtime (between 1.1.2009 and 1.2.2009) OR createtime == 5.2.2009, I got the problem that i don't know how to achieve this with different filter-calls. Because of the programs logic it's not possible to use s= s.where(_or(files.c.createtime.between(val1, val2), files.c.createtime == DateTime('2009-02-01')))
Thanks in advance,
Christof
You can build or clauses dynamically from lists:
clauses = []
if cond1:
clauses.append(files.c.createtime.between(val1, val2))
if cond2:
clauses.append(files.c.createtime == DateTime('2009-02-01'))
if clauses:
s = s.where(or_(*clauses))
If you're willing to "cheat" by making use of the undocumented _whereclause attribute on Select objects, you can incrementally specify a series of OR terms by building a new query each time based on the previous query's where clause:
s = select([files]).where(literal(False)) # Start with an empty query.
s = select(s.froms).where(or_(s._whereclause,
files.c.createtime.between(val1, val2)))
s = select(s.froms).where(or_(s._whereclause,
files.c.createtime == datetime(2009, 2, 1)))
Building up a union is another option. This is a bit clunkier, but doesn't rely on undocumented attributes:
s = select([files]).where(literal(False)) # Start with an empty query.
s = s.select().union(
select([files]).where(files.c.createtime.between(val1, val2)))
s = s.select().union(
select([files]).where(files.c.createtime == datetime(2009, 2, 1)))