数据导入 Lakehouse 操作实践：通过 COPY 命令批量加载

本指南将帮助您通过脚本方式和云器Lakehouse SQLLine命令行工具，将大量公共URL Parquet文件中的数据（例如New York City Taxi and For-Hire Vehicle Data）导入到云器Lakehouse中。

download_raw_data.sh：将 Public URL Parquet 文件下载到本地。本文以NYC Taxi Data为例，包含450多个文件，60GB的数据（Parquet格式）。
initialize_database.sh：通过 Lakehouse SQLLine 命令创建云器 Lakehouse 的 schema 和 tables。
Import taxi and FHV data：用 R 转换 Parquet 文件到 CSV 文件，通过 Lakehouse SQLLine COPY 命令将本地 CSV 文件里的数据导入到云器 Lakehouse 的表里，支持批量多个文件的导入。

操作指南

脚本下载地址：https://github.com/yunqiqiliang/nyc-taxi-data-clickzetta

1. Install ClickZetta SQLLine

2. Install R

From CRAN

Note that R used to be optional for this repo, but is required starting with the 2022 file format change. The scripts use R to convert Parquet files to CSV before loading into Postgres. There are other ways to convert from Parquet to CSV that wouldn't require R, but I found that R's arrow package was faster than some of the other CLI tools I tried

3. Download raw data

./download_raw_data.sh

When done, modify download_raw_data.sh and run again to download data from 202212: wget -i setup_files/raw_data_urls_new.txt -P data/ -w 2

4. Initialize database and set up schema

./initialize_database.sh

5. Import taxi and FHV data

./import_yellow_taxi_trip_data.sh

./import_green_taxi_trip_data.sh

./import_fhv_taxi_trip_data.sh

./import_fhvhv_trip_data.sh

Note that the full import process might take several hours or possibly even over a day, depending on computing power.

Schema

trips table contains all yellow and green taxi trips. Each trip has a cab_type_id, which references the cab_types table and refers to one of yellow or green
fhv_trips table contains all for-hire vehicle trip records, including ride-hailing apps Uber, Lyft, Via, and Juno
fhv_bases maps fhv_trips to base names and "doing business as" labels, which include ride-hailing app names
nyct2010 table contains NYC census tracts plus the Newark Airport. It also maps census tracts to NYC's official neighborhood tabulation areas
taxi_zones table contains the TLC's official taxi zone boundaries. Starting in July 2016, the TLC no longer provides pickup and dropoff coordinates. Instead, each trip comes with taxi zone pickup and dropoff location IDs
central_park_weather_observations has summary weather data by date

加载脚本示例

完整脚本


#!/bin/bash

fhv_schema="(dispatching_base_num, pickup_datetime, dropoff_datetime, pickup_location_id, dropoff_location_id, legacy_shared_ride_flag, affiliated_base_num)"

for parquet_filename in data/fhv_tripdata*.parquet; do
  echo "`date`: converting ${parquet_filename} to csv"
  ./setup_files/convert_parquet_to_csv.R ${parquet_filename}

  csv_filename=${parquet_filename/.parquet/.csv}
  
  sh ../sqlline_cz/sqlline properties ../sqlline_cz/clickzetta.properties -e "set copy.csv.with.header=false;set copy.csv.skip.header=true; copy fhv_trips_staging from '${csv_filename}';"

  echo "`date`: finished raw load for ${csv_filename}"

  rm -f $csv_filename
  echo "`date`: deleted ${csv_filename}"
done;

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