Insert Update Delete Using Dataset Csv
You will see the Import dialog window. The left-hand panel is for format specification:choose the delimiter, if the first row is the header (the separate format options areavailable for it), and specify if you have quoted values in the file.On the right-hand side, you see the frame describing the table to be created and the resultdatapreview. Press Delete to remove a column from the result.
Ifyou want to import data from an existing table, just use the context menu of this particulartable to choose Import From File.
Either way, if those are small CSV files, you will get your job done easily. But what if you need to import large CSV files (100MB / 1M rows)?
The ProblemFor a recent project I worked on, an external system would send a CSV file containing 200k rows every 15 minutes. Aforementioned solutions were simply not good enough; they were slow and ate up a bunch of RAM.I knew I had to find a more efficient solution. First Try: CSVImporter gemBecause of its simplicity, I first decided to use the gem. After installing the gem, the CSVImporter class was defined like this: class ForecastCSVImporter include CSVImporter model Forecast column:property column:date column:value column:type column:location column:createdat endExecuting an import for a specific file was done like this: ForecastCSVImporter. New ( path: filepath ).
Insert Update Delete Using Dataset Csv Windows 10
Run!The implementation was simple and it worked really well on a test CSV file. Then I decided to test it in production, but it was too slow. Importing took more than 2 hours which was fairly bad. The main problem was that each CSV row had to be converted into an ActiveRecord model and had to call #create.I have tried many different gems and wrote a custom CSV importer by using plain Ruby CSV with batch insert commands. Performance improvements were noticeable and the import time was reduced to around 45 minutes, but it was still too slow. I felt I still wasn't on the right track.Solution - Use COPYAfter all of these attempts, I finally gave up on Ruby solutions and looked for help from my database.I found that PostgreSQL has a really powerful yet very simple command called which copies data between a file and a database table.It can be used in both ways:.
Csv Dataset Download
to import data from a CSV file to database. to export data from a database table to a CSV file.Example of usage: COPY forecasts FROM 'tmp/forecast.csv' CSV HEADER;This piece of SQL code will import the content from a CSV file to our forecasts table. Note one thing: it's assumed that the number and order of columns in the table is the same as in the CSV file. ResultsImporting a CSV file with 1M rows now takes under 4 seconds which is blazing fast when compared to previous solutions! Library SupportUsually, when writing application code, it's good to avoid writing raw SQL. By default, ActiveRecord doesn't support the COPY command but there is a gem which takes care of that. The gem provides a simple interface for copying data between a database table and a CSV file.Let's see an example: # Enable COPY command on Forecast model class Forecast.