datastax - Issue with blobs (Cassandra driver, Python) -


as part of testing, i'm using cassandra python driver trying select , delete rows on 1 of tables generated cassandra stress tool (standard1, on keyspace1). standard1 consists of several blob columns.

my approach extract (primary) key rows , run loop delete rows based on that.

the problem i'm facing looks cassandra driver converts blobs (hex bytes) strings, when try pass delete statement fails "cannot parse 'xxxxxx' hex bytes".

the data in table on cqlsh looks "0x303038333830343432", whereas below select extracts keys as, i.e., '069672027'.

is there way of preventing hex bytes being converted strings? other approach should using?

thanks!

query  = simplestatement("select (key) \"standard1\" limit 10", consistency_level=consistencylevel.local_quorum) rows = session.execute(query) row in rows:      query = simplestatement("delete \"standard1\" key = %s", consistency_level=consistencylevel.local_quorum)      session.execute(query, (row.key, ))

when using simple (unprepared) statements, need create buffer string in order encoder recognize blob type.

http://datastax.github.io/python-driver/getting_started.html#type-conversions

try this:

session.execute(query, (buffer(row.key),)

alternatively, binding prepared statement implicitly.


-

Comments

Post a Comment

Popular posts from this blog

.net - Bulk insert via Dapper is slower than inserting rows one-by-one -

i'm using dapper insert data realtime feed sql server, care performance. recently, noticed strange. out of box, if give dapper collection , insert query, fires insert statements each element. tests show can insert 1800 objects 12 fields in 1 second way (counting connection.execute(...) running time. now, didn't find batch insert functionality in dapper , implemented own (constructing parameter list , sql query). after that, found out can insert 1 batch in 3 seconds (which limited 1000 rows) (again, counting connection.execute(...) calls. so, makes batching 6 times slower sending each row in separate query. can explain me? thought people use batch operations speed process. insert time 1 second @ most. use sql server 2012 standard on local network. table i'm inserting has clustered index on primary key (which bigint field), no non-clustered indexes , triggers. can post code, there's nothing special i'm not sure why using dapper execute extension ...
Read more

shared memory - gstreamer shmsrc and shmsink with h264 data -

i trying share h264 encoded data gstreamer 2 processes(both based on gstreamer).after research way found use shm plugin. trying do gstreamer--->h264 encoder--->shmsink shmrc--->process1 shmrc--->process2 i able raw data videotestsrc , webcam working. h264 encoded data doesn't. test pipeline gst-launch-1.0 videotestsrc ! video/x-raw,width=640,height=480,format=yuy2 ! x264enc ! shmsink socket-path=/tmp/foo sync=true wait-for- connection=false shm-size=10000000 gst-launch-1.0 shmsrc socket-path=/tmp/foo ! avdec_h264 ! video/x- raw,width=640,height=480,framerate=25/1,format=yuy2 ! autovideosink have tried shm plugins h264 encoded data, please help iam not aware of capabilities of sink used in "autovideosink", per knowledge either need use videoconvert if format supported sink (like kmssink or ximagesink) different provided source (in case yuy2) or use videoparse if camera format supported sink. may check using gst-inspect-1...
Read more

python - Error importing VideoFileClip from moviepy : AttributeError: 'PermissionError' object has no attribute 'message' -

i'm using jupyter notebook. have tried anaconda console well. tried importing both ways shown below from moviepy.editor import videofileclip moviepy.video.io.videofileclip import videofileclip both of them gave me same error. full trace below attributeerror traceback (most recent call last) <ipython-input-10-9afa9d6e87c4> in <module>() 6 import glob 7 import math ----> 8 moviepy.editor import videofileclip 9 moviepy.video.io.videofileclip import videofileclip c:\program files\anaconda3\lib\site-packages\moviepy\editor.py in <module>() 20 # clips 21 ---> 22 .video.io.videofileclip import videofileclip 23 .video.io.imagesequenceclip import imagesequenceclip 24 .video.io.downloader import download_webfile c:\program files\anaconda3\lib\site-packages\moviepy\video\io\videofileclip.py in <module>() 1 import os 2 ----> 3 moviepy.video.videoclip import videoclip ...
Read more