Query large CSV file as a data source?

[matthias_livecode_150811 at m-r-d.de]

Regarding the loop.

you could do a

put the detailed files 

to get the file size of that csv file.

With that size you would now how often you have to run the loop





-
Matthias Rebbe
Life Is Too Short For Boring Code

> Am 03.11.2020 um 15:14 schrieb Keith Clarke via use-livecode <use-livecode at lists.runrev.com>:
> 
> Thank you Matthias, I wasn’t aware of that ability to open the file and read its contents straight from the disk. 
> 
> A quick experiment looks positive - no hanging and fast access - so I just need to work on the loop.
> 
> Much obliged.
> 
> Best,
> Keith   
> 
>> On 3 Nov 2020, at 13:37, matthias rebbe via use-livecode <use-livecode at lists.runrev.com> wrote:
>> 
>> Couldn't you read the file partially
>> 
>> you would open the file for read
>> 
>> 	open file tFile for read
>> 
>> then in a repeat loop you could read e.g. 10000 lines and process the data
>> 
>> 	read from file tFile for 10000 lines
>> 
>> 
>> Just a thought.
>> 
>> 
>> -
>> Matthias Rebbe
>> Life Is Too Short For Boring Code
>> 
>>> Am 03.11.2020 um 13:14 schrieb Keith Clarke via use-livecode <use-livecode at lists.runrev.com>:
>>> 
>>> Hi folks,
>>> I’ve a 3GB CSV file with 18M rows from which I need to create a subset CSV file for the rows containing tString. The following script results in LiveCode becoming unresponsive, so I’m wondering if I’m missing an obvious trick or what alternative approach I might take...
>>> on mouseUp pButtonNumber
>>> 
>>> -- Select CSV File
>>> 
>>> answer file prompt as sheet
>>> 
>>> put it into tFile
>>> 
>>> put tFile into field "File"
>>> 
>>> -- Process CSV extract
>>> 
>>> put URL ("file:" & tFile) into tText
>>> 
>>> put line 1 of tText into field "List"
>>> 
>>> filter lines of tText with "*tString*"
>>> 
>>> put tText into field tList
>>> 
>>> end mouseUp
>>> 
>>> I don’t normally deal with large data sets, so maybe LiveCode isn’t the best tool for this but Excel 365 seems to only offer CSV file import, not query.
>>> 
>>> Any thoughts greatly appreciated.
>>> 
>>> Thanks & regards,
>>> Keith
>>> _______________________________________________
>>> use-livecode mailing list
>>> use-livecode at lists.runrev.com
>>> Please visit this url to subscribe, unsubscribe and manage your subscription preferences:
>>> http://lists.runrev.com/mailman/listinfo/use-livecode
>> 
>> 
>> _______________________________________________
>> use-livecode mailing list
>> use-livecode at lists.runrev.com
>> Please visit this url to subscribe, unsubscribe and manage your subscription preferences:
>> http://lists.runrev.com/mailman/listinfo/use-livecode
> 
> 
> _______________________________________________
> use-livecode mailing list
> use-livecode at lists.runrev.com
> Please visit this url to subscribe, unsubscribe and manage your subscription preferences:
> http://lists.runrev.com/mailman/listinfo/use-livecode